Archive for the 'Biological Control' Category

Our Vision for Successful SPM – Part 7: What has to be different for SPM? [Hint: Life]

Ron Whitehurst, PCA and owner Rincon-Vitova Insectaries, Inc.

“Working with these species in a bio-diverse agroecosystem will require specific training and the ability to evaluate the pest-crop-beneficial input dynamic in very diverse locations. Biological control is a cornerstone of IPM.” – Entomologist Lynn LeBeck, Executive Director, Association of Natural Biocontrol Producers 

In biodiversity-based farming systems, also referred to as regenerative organic, farmers reduce inputs and increase profit through building soil and plant health and increasing biodiversity. Sustainable Pest Management (SPM) recognizes that successfully transitioned regenerative organic farms have few pest problems and little or no pesticide use. This is because natural control is achieved by the presence of a pests’ natural enemies maintaining a proportionately high ratio. To support the transition to regenerative organic farming, monitoring and interventions related to biological control is a major field for Research and Extension investment along with development of new effective biopesticides for the Roadmap to achieve its goals. For six decades the centrality of biological control has been understood by leaders of thought about pest management.

In this article we survey contributions to the history of Integrated Pest Management (IPM) to understand why it has not prevented pest infestations, nor reduced the number of new pesticides or the level of their use, and explore what needs to be different when using Sustainable Pest Management (SPM).


My mentor, Deke, met Prof Harry Smith and his cadre of biocontrol entomologists when he want to graduate school at UC Berkeley on the GI bill after serving in the Coast Guard in the Pacific Theater. He appreciates Richard Doutt for directing him to the biocontrol team. Deke left Berkeley for a job at the University of California Citrus Research Station and after 12 years doing field research in many crops, he left the university because there was no more funding to do biological control research. He wrote, 

“UC Farm Advisors and county agents in addition to the UC researchers in the Department of Entomology were particularly supportive of pesticides.  Only a very few would carry on a dialog about integrated control and least of all IPM.  Their mantra was to apply pesticides whenever what was left of the natural biological control failed and of course it failed when broad spectrum chemicals were applied.  Integrated control was monitoring and spraying every time the economic threshold was reached.” [Unpublished memoirs]

He built a business mass-producing beneficial insects and selling a service to farmers that he called “Supervised Control”. Deke’s insights and enthusiasm convinced farmers in the Imperial and Coachella Valleys to stop calendar DDT spraying of cotton by selling egg parasitoid wasps (Trichogramma) for cotton bollworm.  Having learned during twelve years with the University of California Department of Biological Control surveying insect ecology on “untreated” farms  in the years prior to “organic”,  his business expanded with a dozen Supervised Control consultants using applied biological control instead of pesticides, successfully persuading farmers of the method’s effectiveness.  

During such conversations with farmers, he often listened for the moment when a farmer was visualizing the interaction of the problem pest and the “natural enemy complex” on his or her farm, as the farmer would eventually ask a question about how the insect ecology worked if you introduced natural enemies. Deke would say, “Food drives all these systems.” As that understanding sank in, the farmer stopped being fearful and began to show curiosity about how to observe insect ecology. Once he or she recognized that both monitoring information and consideration of alternative actions focused on conserving natural enemies, the farmer rarely ever resorted to chemical pesticides again. These are the same principles, features, and pedagogy that direct our company Rincon-Vitova Insectaries today.


In a 50th anniversary commemoration of what is considered the “most important” pest control paper of the 20th century, a 2009 article in California Agriculture recognizes the scientists behind the framework that became Integrated Pest Management. The 20-page paper explains the damage from pesticides and proposes the consideration of multiple methods that would be more effective and better protect farmworkers and the environment. The commemorative article summarizes IPM principles without giving full credit to their development in the work of field researchers like Everett Dietrick who developed the applied insect ecology strategies first called “Supervised Control”:

  • Recognition that agriculture is part of a larger ecosystem, comprised of all the living organisms of an area and their environment.
  • Supervision of insect levels so that chemical applications take place only when and where they are absolutely necessary.
  • Promotion of beneficial insects through conservation and augmentation.
  • Use of products and application timing to target specific pests, minimizing the effect of treatment on pests’ natural enemies.

Authors of the visionary article, Vernon M. Stern, Ray F. Smith, Robert van den Bosch and Kenneth S. Hagen, are now called ‘the fathers of IPM’. However, Deke would say that the concepts came out of the preceding decade of development of Supervised Control by the larger team of field researchers and consultants. Vern Stern’s primary contribution was that he recognized the collective visionary insights of those around him and led in writing them down.


Deke recalled passing the exam in all categories in 1974. He wrote, 

“There was nothing written or questions asked about the ecological basis of pest management and natural biological control. It seems that IPM is all about chemicals and mortality from these powerful pesticides and not about beneficial insects and the interference of the pesticide applications to the work of these biological control organisms. Applied biological control organisms were not covered, nor was there anything suggesting that natural enemies are destroyed in a blowback and resurgence of pests following a pesticide application.” [Unpublished memoirs]


Clara Nichols and Miguel Altieri in their book chapter entitled “Agroecology: contributions towards a renewed ecological foundation for pest management”, explain the theoretical principles about transition in a farming system framework. They state that the desirable attributes of stability and resource conservation “are connected to the higher levels of functional biodiversity associated with complex farming systems.”  It is clear, they say (referring to Southwood and Way, 1970) that insect population stability depends on “the actual density-dependence nature of the trophic levels”, not just on trophic diversity, specifically on who eats who.

In other words, stability will depend on the precision of the response of any particular trophic link to an increase in the population at a lower level.” 

They also had this to say about biodiversity-based farming systems: 

“Diverse systems encourage complex food webs which entail more potential connections and interactions among members, and many alternative paths of energy and material flow through it. For this and other reasons a more complex community exhibits more stable production and less fluctuations in the numbers of undesirable organisms.”

1994 INTEGRATED PEST MANAGEMENT: THE PATH OF A PARADIGM by James R. Cate and Maureen Kuwano Hinkle. Excerpts from recommendations, pages 30-33:

  • The first need is…a clearly articulated definition of IPM that goes beyond use of monitoring and economic thresholds restoring the ecological basis of IPM.
  • Regulatory incentives can encourage the development and registration of biological alternative products.
  • Pest management should be directed at developing solutions that provide durable, long-term controls [by] a systematic assessment of key pests and the nature of the ecological upset or imbalance that has caused a pest problem.
  • Funding of programs needs to be maintained over a decade or more and implementation projects often require three to six-year commitments. 
  • Funding needs to be allocated in a way that avoids agency competition, turf disputes, and conflicting purposes [in a] competitive grants program of basic research, mission-oriented research, and implementation grants…
  • Adoption by farmers…is best accomplished by having the users be active participants in the development and implementation teams….A team building structure would help to diffuse technological advances quickly and establish a social and cultural receptivity to continued practice and improvement of IPM…
  • The advice should not be influenced by the commercial need to generate sales of specific products. 
  • Inducements could be in the form of crop risk insurance for users and private crop consultants and in the form of IPM program development incentives to users, particularly during the transitional periods when growers are moving to ecologically based management from chemically based management.
  • Inducements could also be in the form of predictive models and information that can be used by consultants and users to forecast pest population models and seasonal growth of crops, pest populations, and populations of biological control agents. 
  • Pest management cooperatives could be encouraged with incentives to assist farmers and neighbors in addressing pest problems in area-wide and systematic ways.
  • Building on the scientific principles that support an ecologically based IPM, and the original concepts of Integrated Control, IPM is a useful organizing principle around which utilization of all technologies can be integrated—biological controls, host resistance to pests, biotechnology, alteration of the cropping system, etc.— to facilitate natural controls or antagonists of the pest or to create a more unfavorable environment for the pest. By focusing on the basic causes… and appropriately addressing different types of pests, we can manage pest populations so they no longer damage crops, goods and human health.

1996 NAS: EBPM

National Academy of Science report (1996), Ecologically Based Pest Management (EBPM) stated that EBPM “should be based on a broad knowledge of the agro-ecosystem and will seek to manage rather than eliminate pests” in ways that are “profitable, safe, and durable.” Its vision was the transition of agriculture to a total-system approach in an agroecological framework.


National Academy of Science (1997) Proceedings paper, “A Total System Approach to Sustainable Pest Management,” went further in calling for “a fundamental shift to a total-system approach for crop protection [which] is urgently needed to resolve escalatory economic and environmental consequences of combating agricultural pests.”  Successful transition to SPM operates in the context of the type of farming system in which one is working. In the context of a new Roadmap for Sustainable Pest Management, we need to be unambiguous about which “system” we are referring to.


As plants developed inherent protective mechanisms against pests, they were assisted by numerous partners in the ecosystem, including:

A total-system approach was then well described in Sustainable Agriculture Research and Education (SARE) Handbook 7, Manage Insects on Your Farm – A Guide to Ecological Strategies (2005) by Miguel A. Altieri and Clara I. Nicholls with Marlene A. Fritz. They wrote that EBPM (EPM for short)

employs tactics that have existed in natural ecosystems for thousands of years. Since the beginning of agriculture— indeed, long before then — plants co-evolved with pests and with the natural enemies of those pests. 

  • Beneficial insects that attack crop-eating insects and mites by chewing them up or sucking out their juices
  • Beneficial parasites, which commandeer pests for habitat or food
  • Disease-causing organisms, including fungi, bacteria, viruses, protozoa and nematodes, that fatally sicken insects or keep them from feeding or reproducing. These types of organisms also attack weeds.
  • Insects such as ground beetles that consume weed seeds
  • Beneficial fungi and bacteria that inhabit root surfaces, blocking attack by disease organisms” [page 2]  


As he explains in this paper, David Headrick, Professor of IPM and Biological Control at Cal Poly SLO, trains PCAs and sees them as a critical link in the transfer of knowledge and skills to the growers for site-specific problem-solving, toward a goal of diverse cropping systems. He also explains that the California State Universities (CSUs) are the primary educational institutions training future PCAs.  So, the CSUs must be included in the discussion regarding implementation. 

Dr. Headrick sees a continuum from chemical-reliant systems to biological-dependent systems, but he supports the framework we have adopted of a continuum of three basic types of farming systems: chemical input-based, biological input-based and biodiversity-based.

Dr. David Headrick in “Scouting for pests – Virtual Avocado Field Day at Cal Poly” 

There may currently be more progress in other parts of the world where public investments are addressing the climate crisis. INRA, the French National Institute for Agricultural Research, began publishing papers in 2015 about a framework for study of farms in transition. Beginning in 2020, it merged with IRSTEA, the French National Research Institute of Science and Technology for the Environment and Agriculture to form INRAE, the French National Research Institute for Agriculture, Food and Environment, creating a critical research mass and pooling of labs and observatories, technical platforms, data repositories, etc. making it uniquely able to perform valuable research on the preservation and restoration of biodiversity and risk anticipation and management, as well as regional agricultural strategies, water resources, digital agriculture, and more. 

The INRA, now INRAE, framework for characterizing farming systems informs the following discussion:


Deke called these systems Conventional Chemical Control (CCC) to distinguish them from Biological Control by Natural Enemies (BC by NE) systems. He often described very different interventions in such systems belonging to neighbors or family members growing the same crops. “Both are right”, he said, “because what works in a BC by NE system won’t work in a CCC system.” 

At one end of the spectrum are chemical input-based systems under eradication programs for invasive species. Since the pest is usually eventually declared established and the state can no longer conduct area-wide eradication, as Dr. David Headrick explains to his Plant Protection students, “Then it’s biological control to the rescue for a long-term solution to avoid economic losses and having to use insecticides.” This leads to a discussion of the problem of pesticide resistance and how to manage that by alternating pesticides with different modes of action. Since their inception, bio-control entomologists have advocated against total eradication programs, because they practically never succeed and the spraying is highly disruptive. 

Another characteristic of chemical input-based farming systems is the degree to which they are embedded in globalized commodity-based food systems that favor large growers and distributors far removed from consumers and end-users. This allows producers to be invisible and thus less accountable for negative health and ecosystem impacts. The Roadmap toward SPM is timely because opposition to the resulting pollution and lack of accountability is steadily growing. 


Distinguishing between biological input-based and biodiversity-based farming systems in the pest management transition continuum is increasingly important. Differences lie not only in the relationship between biodiversity and biological control of pests described above.  We now have insights that increasing biodiversity is correlated with accelerated timelines and community tipping points when sufficient multiple species are growing together. Beneficial increases in measures of soil health, carbon sequestration, plant fertility, pest resistance, water penetration and water-holding capacity, and resilience to climate impacts all result.  Past understandings of risk to benefit ratios and economics are shifting toward a wider scope of valuable characteristics not always found on typical organic farms that are biological input-based systems. 

Biological input-based systems (most organic acreage in California) are still usually relatively simple systems and not evolved to provide much in the way of the above-described biodiversity benefits compared to what is experienced in regenerative farming systems that build on the best practices for soil aeration, hydration, protection and fertility with well-developed and conserved soil microbial biodiversity and habitat enhancements for natural enemies.  Biological input-based farming systems are a middle area of the continuum between chemical inputs and biodiversity-based systems that have more complexity and more resilience with fewer inputs.

The “efficiency/substitution” paradigm analyzed by INRAE scientists, especially when it prioritizes “alternatives” without the end-goal of biodiversity, limits the language and patterns of thinking in contrast to a more biodiversity-based paradigm for transition. Successful consultants in regenerative agriculture within our network quickly recognize the limiting belief that soft chemical or biopesticides are essential for SPM.  Experts holding the paradigm of “efficiency/substitution” are understandably averse to setting goals for transition to organic, because from a farming system perspective it is far from perfect with some strict prohibitions that are not pragmatic. 

However, there is no doubt that the organic label from a policy and economic perspective will drive adoption of SPM. The federal government is investing in transition to organic and the state must do so as well by removing all fees and inspection costs, by providing a full day of expert consultation toward an Organic Farm Plan, and by requiring the public kitchens purpose increasing percentages of local organic products. Organic farming systems are not the objective, but rather a stepping-stone on the path to regenerative biodiversity-based farming systems. The marketing value of the organic label cannot be squandered. It is the ideal metric for incentivizing accelerated soil carbon sequestration and advancing SPM. Buyers can be educated and also in some cases required by their institutions to seek out those inquisitive, determined, pioneering organic farmers that have at least begun to care for the soil and wildlife, have stopped toxic chemical inputs, and are on the path to profitable biodiversity-based farming systems. 

Hence, the SPM Roadmap must feature the recognized co-benefits of biodiversity PLUS the following: 

  1. Biodiversity-based systems offer long-term success that is unlikely when “alternatives” and substitution of soft chemical and biopesticides are disproportionately spotlighted in the middle part of the farming system continuum. 
  2. The organic label is the most powerful metric to drive consumer investment and rapidly scale transition regardless of the scientific rationale of the standards or the net value to farmers of inputs and practices. If there are anomalies or absurdities in the Organic Standard, they can be fixed while focusing investment in transition to organic. 
  3. Regenerative organic agriculture is trending and is powerful in featuring incentives beyond the basic organic label, because of its focus on soil carbon and potential carbon or eco-credits, not to mention it providing the greatest economic and ecological resilience or the farmer. 


We don’t want alternatives. We want to do what is actually most effective for the long term. The limiting paradigm of “efficiency/substitution”-based agriculture and the limits of a “sustainable agriculture” framework are discussed in two papers from the preeminent research team at INRA [Duru 2015; Therond, 2017]. In the Duru paper the limiting aspect of the “efficiency/substitution paradigm” relative to the “biodiversity paradigm” is discussed. Framing transition in an “alternative or substitution mindset” will increasingly limit capacity to do what is most effective in the long-term. “Substitution thinking”, in fact, has already led to unfarmable land because of climate impacts. That is just the beginning of the difficulties that lie ahead.

“Efficiency/substitution” farming systems are often held up as “Best Management Practices” in a hierarchy of recommendations in UC-IPM publications with conventional chemical control presented FIRST and biological control presented as a chemical substitution or alternative. As such, the University of California imposes a top-down hierarchy of upside-down guidelines resulting from partnering with the companies selling patented products for profit.  The aim of these companies, and the researchers funded by them, is increasing efficiency and reducing costs and pollution by comparing a lower-risk alternative with a chemical control in a chemical input-dependent farming system test plot. Where is the biodiversity-based control?

At the meetings where Pest Control Advisor’s pay to receive Continuing Education Units, they generally hear product representatives and Farm Advisors sharing new information about which product killed more pests and what additional crops a pesticide produce label now covers. There is nothing on a chemical label about approved use of a product on a farm in transition away from being chemical input-based, such as potentially spot spraying based on a modified action level. Experts teach that their findings are uniformly applicable across all farms. By contrast, what if there were CEUs given for PCAs to learn how to recognize or build a biodiverse, problem-free system anticipating no need for alternatives to chemical pesticides?

I made a proposal recently to talk about biological control and cover crops that was rejected by DPR for CEUs. Our General Manager with nearly two decades of experience helping customers manage pests biologically was required to take twelve hours of courses in production farming and IPM centered around pesticide laws and regulations. She can now take the PCA exam and little to no questions will reveal the depth of her knowledge about SPM. The current dominance of the “efficiency/substitution” paradigm needs to change.  The pendulum seems to swing back and forth regarding acceptance of CEU’s for ecological approaches.

Farmers who demand urgent availability of “alternative” products before agreeing to consider changes in their practices are seriously hurting themselves. Climate impacts and particularly water shortages will teach them that they should have prioritized transition and said goodbye to pest management tools that hold them back.  The Roadmap should nowhere even faintly suggest that “alternative” inputs are the end-goal for SPM when we know that durable transition is attainable by increasing above- and below-ground biodiversity with its co-benefits, including low incidence of pest problems. 

In the words of Dr. Annemiek Schilder, Director of the Ventura County University of California Cooperative Extension office, 

“In the end, it is all about increasing biodiversity across the system, from the soil and roots to above-ground plant parts to the landscape and region, to increase efficacy and resiliency/robustness of the agroecosystem. There is a lot we don’t know, especially how soil health affects plant health….Within this, there needs to be a focus on understanding ecological principles, interactions and population dynamics of beneficial and pest species, as well as the role of and how to measure farm biodiversity. Also, is all biodiversity good or do we need specific components for a pest/disease-suppressive system?”

Dr. David Headrick, Entomology Professor at Cal Poly San Luis Obispo also encourages research that helps discriminate about how to diversify the cropping pattern: 

“In thinking about the tactic of diversifying the farmscape, I hope that the SPM workgroup can appreciate and acknowledge that diversification of an agroecosystem occurs on a spectrum.  On one end of the spectrum you can have the addition of a single plant to a monocrop; on the other end of the spectrum you can have hedgerows and insectary plantings in a polyculture farmscape.  It would be wrong not to acknowledge the efforts of current growers in Salinas in diversification.  Twenty years ago, the standard method for aphid control in row crops was an early application of Metasystox-R, an extremely dangerous systemic organo-phosphate.  But now many of them plant sweet alyssum to attract syrphid fly predators and get excellent control of aphids. This is thanks to the work of Eric Brennen with the USDA-ARS at his organic research farm in Salinas, and others.  By adding one additional plant – increasing the diversity of the cropping system – they have an excellent tool that invokes the natural aphid control provided by naturally occurring syrphid flies.”  

“So, on one end of the spectrum, we can have a single plant increasing the diversity of a monocrop that eliminates the need for one of the worst insecticides.  To me that is remarkable, worthy of note and is a significant step on the Roadmap toward Sustainable Pest Management and should be acknowledged as such.  This example also shows the successful collaboration of the research and grower communities.  At first, the alyssum was planted in several rows throughout the field, but growers were concerned about reduced productivity.  Dr. Eric Brennan, USDA/ARS Research Horticulturist and specialist in organic and climate-smart farming in Salinas, has been extending research done by Bugg et. al. (2008) showing that alyssum plants could be placed randomly in the fields at much reduced numbers and still maintain excellent aphid control without compromising productivity.”

The guiding principle that lifts SPM beyond IPM is that natural control is the end goal for successful transition. To help understand why this is so, we need to understand how living organisms communicate with each other in diversified agroecosystems. The interconnectedness has never been much of a feature in the practice of IPM. Nature exercises forces that must be part of the SPM knowledge base. The glimmer of knowledge available about heterospecific and conspecific communication in soil and above-ground food webs helps us appreciate pure entomological research AND respect intuitive ways of knowing. Our ignorance about natural phenomena is boundless compared to the tiny, usually biased glimmer we get from peer reviewed papers. 

For example, underlying plant-insect communication, we now know that by monitoring soil and especially also plant sap, practitioners can assess a plant’s health and capacity to resist pests. We can develop biological action levels for customized foliar nutrient and biostimulant sprays or side-dressings that shift the bioavailability of key nutrients to enhance plant defense mechanisms. Dr. Phillip A. Callahan spent decades researching and reporting on these phenomena showing that a healthy plant emits molecules and low energy electromagnetic waves that essentially repel pests while unhealthy, nutritionally out-of-balance plants attract pests. Dr. Tom Dykstra, a student of Dr. Callahan, founded a lab to continue this study and its application in agriculture.  

As I discussed in Part 6: “New knowledge for pest prevention” other research shows that molecules emitted by healthy plants continue for up to five days to protect neighboring plants [Sharma, et. al 2017]. Healthy plants can detect certain terpenoid molecules that cause an influx of calcium ions and membrane depolarization that can impact an herbivorous insect’s chewing ability.  It requires a lively soil biology for plants to access the calcium, sulfur and other minerals that are there in the soil and have such a widespread effect on the entire ecology including insect physiology. 

Moreover, complex plant communities of at least eight species support each other in the root zone to bump up nutrient cycling and fertility. Arbuscular mycorrhizal fungi around plant roots stimulate systemic tritrophic interactions in the soil ecology. Plants living in such lively root systems emit molecules that consistently direct insect behavior. For example,

“All plants synthesize a suite of several hundred terpenoid compounds with roles that include phytohormones, protein modification reagents, anti-oxidants, and more. Different plant lineages also synthesize hundreds of distinct terpenoids, with the total number of such specialized plant terpenoids estimated in the scores of thousands. Phylogenetically restricted terpenoids are implicated in defense or in the attraction of beneficial organisms.” [Pichersky and  Raguso, 2017].

These molecular and bioelectromagnetic phenomena of living ecosystems are important for carbon farming as well as the SPM knowledge base.

The implications of the complexity in biodiversity-based systems seem miraculous. It is a challenge to measure or model the complexity that should characterize living ecosystems. It is generally not a straight-line linear correlation between diversity and systemic functionality such as where tipping points of biodiversity accelerate all healthful functions in the plant, including the amount of deposition of soil organic carbon, nitrogen availability, and molecules involved in defense mechanisms. This hyphal/molecular/bioenergetic/epigenetic world is the boundary where SPM can leave IPM behind.

Board Certified in multiple entomology specialties, my mentor Everett Dietrick studied the scientific literature, attended and sometimes presented at top scientific conferences, and maintained close communication with researchers around the world, but he frequently said that his own repeated observations were equally applicable compared to the knowledge base available in the scientific community. From decades of sweeping with a standard sweepnet and the D-Vac Vacuum Insect Net that he co-invented, his comprehensive monitoring of a field in the farmscape context often yielded exceptional intuitive insights about population dynamics and strategies to tip the balance in favor of natural enemies. Strong training to develop deep curiosity about relationships in the natural world and personal capacity for other ways of knowing will make SPM more successful than IPM in pesticide use reduction. 


Altieri, Miguel A. and Clara I. Nicholls with Marlene A. Fritz. Handbook 7, Manage Insects on Your Farm – A Guide to Ecological Strategies. Sustainable Agriculture Research and Education (SARE), 2005. 

Bugg R.L., R.G. Colfer, W.E. Chaney, H.A. Smith, J. Cannon. 2008. Flower flies (Syrphidae) and other biological control agents for aphids in vegetable crops, University of California, Division of Agriculture and Natural Resources.

Callahan, Phillip (1965-1975). 36 published papers summarized on The Free Library page “Electromagnetic communication and olfaction in insects”.

Duru, M., Therond, O., Martin, G. et al. How to implement biodiversity-based agriculture to enhance ecosystem services: a review. Agron. Sustain. Dev. 35, 1259–1281 (2015).

Dykstra, T. How Insect Pests Identify Unhealthy Plants. Regenerative Agriculture Podcast with John Kempf. 

Headrick, David. The Future of Organic Insect Pest Management: Be a Better Entomologist or Pay for Someone Who Is, Insects 2021, 12(2), 140;

Nichols, Clara and Miguel Altieri, “Agroecology: contributions towards a renewed ecological foundation for pest management” in Ecological Theory and Integrated Pest Management Practice, ed Marcos Kogan, 1986.

Cate, James R. and Maureen Kuwano Hinkle, Integrated Pest Management: The Path of a Paradigm. Audubon Society, 1994.

National Academy of Science-National Research Council, Ecologically Based Pest Management (EBPM)-New Solutions for a New Century, 1996.

Pichersky, Eran and Robert A. Raguso, Why do plants produce so many terpenoid compounds? New Phytol 2018 Nov;220(3):692-702. doi: 10.1111/nph.14178.

Sharma, E., Anand G., & Kapoor, R. (2017). Terpenoids in plant and arbuscular mycorrhiza-reinforced defense against herbivorous insects. Annals of Botany, Volume 119, Issue 5, March 2017, Pages 791–801,

Southwood, T. R. E., and M. J. Way. 1970. Ecological background to pest management. Pages 6–28in R. L. Rabb and F. E. Guthrie, eds. Concepts of pest management. North Carolina State University, Raleigh, NC.

Therond, O., Duru, M., Roger-Estrade, J. et al. A new analytical framework of farming system and agriculture model diversities. A review. Agron. Sustain. Dev. 37, 21 (2017).

Van Lenteren, J., Sharad C. Phatak, James Tumlinson. “A Total System Approach to Sustainable Pest Management,” National Academy of Science – Proceedings paper,1997. 

Warnert J. 2009. The 50th anniversary of a great idea: Landmark article on “integrated control” considered “most important” pest control paper of 20th century. Calif Agr 63(4):160-161.



Our Vision for Successful SPM – Part 6: New knowledge for pest prevention

Ron Whitehurst, PCA and co-owner Rincon-Vitova Insectaries, Inc.

Our vision for successful Sustainable Pest Management is that UCCE Farm Advisors, farmers, PCAs, CCAs, and field scouts – all farm personnel – effectively monitor pests and biological control in a landscape approach for predicting populations and evaluating interventions appropriate to the farming system. They enhance biological control and eliminate or decrease pest problems below economic injury levels. 

We imagine future training and extension of biological control practices and tools available to everyone who is interested. They learn preventive cultural practices, habitat enhancement, and determination of biological action levels for colonization and/or augmentative release of natural enemies and/or application of biological and National Organic Program (NOP) approved pesticides.

PCAs and farmers can reduce pest problems and be more profitable. PCAs will guide farmers to build biodiversity-based systems, i.e. build soil, grow healthy plants that do not attract pests, build reservoirs of natural enemies and anticipate that pest population densities will stay below pesticide action levels resulting in no need for any pesticides because they do not want to disrupt the biological control. .

SPM EDUCATORS AT THE CENTER OF REGIONAL PLANNING:  All of our entomology professor friends who teach Pest Control Advisors (PCAs) cite the need for better support and communication with the Department of Pesticide Regulation and the California Department of Food and Agriculture. PCA’s must get Continuing Education Credits for learning from experts (now largely from the biocontrol industry) what they must know about the centrality of biological control and how it is achieved. 

Ruben Alarcon at CSU Channel Islands said entomology professors at CSUs and community colleges are sometimes brought in as an after-thought. It is usually Farm Advisors and product representatives offering Continuing Education Units (CEUs), not the professors teaching IPM or biological control. The knowledge needed is currently not approved for CEU course content.This must change immediately. 

If entomology professors would be consulted at the start of SPM curriculum development their advice would be to:

  • Include landscape level insect monitoring with a focus on natural enemies of key pests in the farmscape, invertebrate species identification, understanding pests and natural enemies as populations, insect movement (population dynamics), and then the more advanced training on determining pest to beneficial ratios and habitat enhancement for particular beneficials. To reiterate because this is so important, effective monitoring is at the landscape level and includes natural enemies as a prerequisite to biological, cultural and physical interventions.
  • Include protection of non-target animal species, including insectivorous birds, birds of prey, amphibians, fish and predatory mammals.  
  • Include understanding of naturally-occurring biological control and its importance for a healthy ecological system that doesn’t require the use of pesticides. 

RESEARCH AND EXTENSION IS IN DECLINE AND MUST BE ALMOST ENTIRELY REBUILT. While we are seeing a constant influx and threat of invasive species, warmer temperatures and extremes affecting pests and their natural enemies, biological control research is more needed than ever. There is an exponential need to train new biocontrol entomological scientists paid to study what farmers need to know. This is difficult when they depend on pesticide manufacturers for their research funding. 

Dr. Lynn LeBeck, the Executive Director of the Association of Natural Biocontrol Producers observes: 

“Our UC and CDFA biocontrol workforce are currently overextended just providing expertise for ongoing pest problems, but both are involved in “proactive” research initiatives for serious insect pests that are either being intercepted routinely or will be in the near future.  Positions vacant due to recent and pending retirements that are, and have had, biological control duties are not being refilled.”

With the very last few biocontrol entomology professors retiring and not being replaced, a huge priority must be put to rebuild the robust infrastructure for research to support SPM that is California’s legacy from before the influence of chemical pesticides. 

The history of our industry since the 1950’s has been in stark contrast to how it has developed in Europe and British Columbia where Dutch, British, Belgian and Canadian governments and agricultural universities helped their insectaries grow internationally. Most beneficial insects sold in the US are grown in those countries. The small amount of research done is by foreign insectaries in collaboration with their universities. Their business model sometimes puts a higher priority on sales over the multi-pronged approach to help farmers transition away from biological inputs. There can be similar conflicts of interest for biological and chemical input sales people. No Pest Control Advisors should be paid commission for their sales. Inputs of any kind are not in the farmer’s best interest if they don’t need them. There should be incentives for PCAs who sell advice to achieve successful programs with the least amount of products.  

Classical or “introduction” biological control is not given importance commensurate with what it achieved in the last century. It alone can quickly turn new pest invasions into non-pests as California’s state entomologists did effectively from 1907 until 1947 before the well-organized influence of the chemical pesticide industry. When plant-feeding insects arrive without their natural enemies, the most effective first strategy is to go to the native home of the pest and research to effectively reunite the natural enemies with their host insect. Most invasive pests are forgotten within one to four seasons as their natural enemies spread and come into balance.  

Biological input-based systems must be understood as the in-between part of the path from conventional chemicals towards biodiversity-based farming systems. They need help when colonization biocontrol or natural biocontrol is a little slow to build up. Augmentative biological control helps fill gaps apparent when monitoring development and maintenance of a biodiversity-based system. 

The California biocontrol industry has been largely either ignored, actively opposed or faced external competition. Rather than be supported to fill this role in transition away from chemical pesticides, it has survived by overcoming one regulatory, ignorant or corrupt UCCE advice, or market barrier after another. US insectaries have developed our knowledge base with the quiet help of a very few researchers, all of them now retired. Yet, we provide the products and services that work for people who do not want to use toxic pesticides. Worst of all, we must compete with some foreign insectary companies that have questionable sales tactics and product quality.

Our industry’s top product quality leaders and expert trainers have been mostly women developing their businesses in spite of the host of barriers too pervasive too describe here.

In the words of Dr. Lynn LeBeck, our industry association executive director:

“The commercial biocontrol producers and distributors in California (and nationwide) receive inquiries daily about how to use beneficial species in a myriad of cropping systems and sometimes all the data is just not extant for each detailed pest/crop/natural enemy. In addition organic production continues to increase in California, along with sustainable practices in general, but the skyrocketing acreage of a few crops in particular, one crop in particular, will overload resources.” 

Tight regulation and intensive testing of cannabis has resulted in some cannabis growers knowing more about non-toxic pest control than in any other crop. Similarly the horticulturists in zoos, arboreta and casinos who can’t or don’t want to use pesticides indoors have been highly observant and insightful biocontrol practitioners. When chemicals are not an option, because of regulations, risky exposures to people or captive wildlife, or personal preference of a manager, these people acquire the knowledge base to be successful. When chemicals are banned and not an option for anybody, then people in all sectors of agriculture and horticulture can learn and teach others to manage pests in biological input-based systems.

Research is needed in how much of what kind of biodiversity works best. Dr. Annemiek Schilder, Director of the Ventura County University of California Cooperative Extension stresses the importance of biological control for SPM and the need for an entirely new category for continuing education (CE) courses. She explains,

“Within this, there needs to be a focus on understanding ecological principles, interactions and population dynamics of beneficial and pest species, as well as the role of and how to measure farm biodiversity. We need to ask, is all biodiversity good or do we need specific components for a pest/disease-suppressive system?” 

Dr. Headrick has the same questions about how to know how much diversity is advisable. The most appropriate biodiversity may just be adding one new plant species to a system (doubling the number of species). He gives the example in sweet alyssum interplantings in Salinas valley lettuce to attract syrphid flies for aphid control that eliminated use of the worst pesticides in that chemical input-based farming system.

As we wean off from chemicals, Dr. Schilder asks: “There may be a temporary increase in pest pressure before a new balance is reached – how long does that take and how do you know you are going in the right direction? Understanding new action thresholds in all crops and varieties will require a substantial amount of research.” Who will do that?

Dr. Schilder has these additional thoughts about research needs:

“Much more testing and monitoring is needed to accurately assess pesticide burden in food and environment. Also, educating the public on relative pesticide exposure risk in the home or living environment vs. food.”

“There should be more funding for research efficacy trials. For many biological fungicides, data on efficacy on many crops and diseases are limited or lacking. More years of trials may be needed due to  variability due to variable weather conditions. We need additional efforts in finding ways to increase efficacy and reliability of existing materials, for instance with additives or blending products. For instance, from our research, we realized adding Nu-Film P (sticker-extender) helps protect bacteria-based products like Serenade, likely by reducing desiccation and UV-degradation.”

“Research is especially important for soilborne and vector-borne diseases where the vector is widespread and difficult to control. Clean (virus-tested) plants also can play a huge role in preventing diseases, especially viruses and virus-like pathogens. If viruses are absent, some insect vectors may not need the level of control that is required in the presence of viruses (National Clean Plant Network”. This will also relate to parasitic plants such as witch’s broom.

“We need research about spray technology–ways to improve coverage and efficacy as well as reduce pesticide burden and drift. Demonstrations are needed for already known technology.”

Biopesticide research, registration and extension is needed to meet rising demand. The EPA recognizes three major classes of biopesticides: Microbial Pesticides, Biochemical Pesticides, and Plant-Incorporated-Protectants (PIPs). Efficacy compares well with chemical pesticides and is safer for farmworkers and neighbors. Being biodegradable and with low volatiles, they do not pollute land, air or water and generally are low risk for beneficial insects and higher organisms and many are approved for use in organic farming. Just like with natural enemies for biological control, education is needed that they exist, that they work, that they do not pose risks as do chemical pesticides, where to get qualified advice, and where to buy them. 

As explained on the Marrone Bio Innovations website,

“Growers will try a new biopesticide product and compare it with their existing pest management programs in demonstration trials. Conducting demonstrations is the best, if not only way to gain adoption. In addition, University Extension researchers will also test pesticide products and provide their recommendations. Therefore, adoption can be faster as more field trials are conducted….In one California survey, growers and PCAs indicated that biopesticide companies should place a heavy emphasis on education in order to establish sustainable use of the product. They indicated that the companies should target specific markets, either by crop, pest or disease. In turn, companies should be very clear about the protection and value being provided to the grower.”

Biopesticides may support biological control but they are NOT biological control. The latter provides potentially more lasting benefits through classical (exploration and colonization) and augmentative biological control (releasing natural enemies to directly reduce pest populations). Biopesticides are important in the middle of the transition continuum–for biological input-based farming systems. There is a great need for proper education to build capacity for more comprehensive monitoring, integration of cultural practices, habitat enhancement, and the use of biocontrol agents and biopesticides that don’t disrupt natural biocontrol. All five of these features of biological input-based and biodiversity-based farming systems require an entirely different knowledge and skill set compared to planting pesticide-coated seeds and spraying or drenching chemicals. Biopesticides are very valuable tools, but biological control is the endgame.

Molecular biology and electromagnetic signals can help explain why biodiversity- based farming systems have few pests. After over 30 scientific papers explaining insect communication, Dr. Phillip Callahan’s discoveries remain outside of the knowledge base for pest management. Dr. Tom Dykstra founder of Dykstra Laboratories Inc. is continuing research showing how bioelectromagnetics explains the influence of electrical signaling on cell communication, growth and plant and animal health. Dr. Dykstra has a specialization in the complex physiological reasons why insects are attracted to dead, dying, or nutritionally poor, i.e. “sick” plants. He has shown measurable results with plant sap or leaf Brix readings reflecting plant nutrient composition, health and pest and disease decline in less than one season to improve soil, crop longevity, nutrient density and flavor, and profitability for producers. 

Illustration by Jan Dietrick inspired by image from Sharma, E., Anand G., & Kapoor, R. (2017). Terpenoids in plant and arbuscular mycorrhiza-reinforced defence against herbivorous insects.

Swiss scientists have also explained the electrical signals stimulated by insects chewing on plants. Wounds increase systemic plant hormone responses that can attract beneficial insects to attack the plant-chewing insect.  (Farmer, et. al. 2020) Another phenomenon in biodiversity-based systems is plant defensive strategies against herbivorous insects from terpenoids and symbiotic associations with arbuscular mycorrhizal fungi in healthy plants. Fungal hyphal networks in soil serve as electrical conduits facilitating the transfer of defense signals and terpenoids between conspecific and heterospecific plants. Terpenoids increase calcium ions and membrane depolarization causing a protective “priming memory” response lasting up to five days.(Sharma et. al. 2017). This is probably the tip of the iceberg in understanding why it is common that biodiversity-based farming systems are often pest-free and disease-free. We don’t have to have any more data than this to see how to design a Roadmap to achieve SPM goals.

Respect must be paid to all ways of knowing and learning for all SPM farm personnel. How can PCAs trained and experienced in determining chemical action levels learn new knowledge and skills to consider more and different variables when determining biological action levels? Then, also, how do PCAs help farmer clients see new options after they have been inundated by decades of pesticide propaganda? 

INRAE, the French National Research Institute for Agriculture, Food and Environment, is the number two agricultural institute in the world. It has evaluated various learning support tools including games that link principles and actions toward biodiversity-based farming to teach decision-making in situations of uncertainty associated with biodiversity-based farming systems. DPR and CDFA should welcome INRAE’s ideas and consultants in the development of curricula to support SPM.

A group training board game for learning decision-making about conservation ecology land management.

Research will help most current farmers to be more efficient and less polluting with agricultural chemicals being used at the chemical input-based part of the transition continuum. However, as learning and change take place, the need will shift to user-friendly decision-support systems which integrate up-to-date scientific knowledge for more biological inputs and biodiversity-based systems. 

Researchers at INRAE see the need for new teaching methodologies including game-based learning tools. The sociological factors are also critical. The Community Alliance for Family Farmers had an outstanding model in the 1990’s called “Lighthouse Farmer Network” that created a lively space for a monthly breakfast or lunch with a short presentation and give and take discussion with successful practitioners trying new sustainable practices. The participative discussion is much more important than the field day observations. Farmers can see what their neighbors are doing. They need to hear how it was approached and what happened. Certainly university experts giving talks is the least transformative pedagogy; more so when most of the research is in product trials where biological control is not one of the comparisons and the goal is resistance management comparing chemical, biopesticide, and genetically engineered plants. 

Duru, et. al. address the training needs:

“Developing biodiversity-based farming systems and multiservice landscapes raises questions about how to manage the “transformational” transition from specialized systems and simplified landscapes to well-established diversified ones. During this transition, variability in ecosystem services may increase greatly until slow variables reach states which provide ecosystem services at expected levels and degrees of biophysical resilience and stability. Uncertainties…may increase during this transition.” 

The transformation to increasingly biodiversity-based farming systems, where pest prevention is achieved through cultural management and habitat diversification to enhance natural biological control, requires a massive transformation in the educational and research infrastructure. Farmers and SPM educators are at the center of the work. Investment in farmer-led research must replace a research infrastructure that has been a marketing arm of the pesticide industry. This revival of the knowledge of biological control entomology with research and teaching personnel is vital. Diverse ways of knowing and learning and internal methods of validating knowledge must be respected along with the mainstream science of conservation and protection of biodiversity. 


Callahan, Phillip S. (1965-1975). 36 published papers summarized on Free Library “Electromagnetic communication and olfaction in insects”.

Callahan, Phillip S., 1975. Insect antennae with special reference to the mechanism of scent detection and the evolution of the sensilla. International Journal of Insect Morphology and Embryology, Vol 4, Issue 5,(381-430).

Duru et. al. (2015) How to implement biodiversity-based agriculture to enhance ecosystem services: a review, INRA Science & Impact, Agron, Sustain. Dev. 

Farmer, Edward E, Yong-Qiang Gao, Gioia Lenzoni, Jean-Luc Wolfender and Qian Wu, 2020. Wound- and mechanostimulated electrical signals control hormone responses, New Phytologist: 227(1037-1050)

Sharma, E., Anand G., & Kapoor, R. (2017). Terpenoids in plant and arbuscular mycorrhiza-reinforced defence against herbivorous insects. Annals of Botany, ncw 263.

Our Vision for Successful SPM – Part 5: Regional Focus 

Ron Whitehurst, PCA and co-owner Rincon-Vitova Insectaries, Inc.

The SPM Roadmap will be released by the California Department of Pesticide Regulation by the end of 2022. It will be a great step forward. To achieve the SPM goals, we believe the focus should be at a regional level. There is a parallel with federal IPM development with four USDA National Institute of Food and Agriculture Regional Centers that coordinate, enhance, and facilitate the flow of resources and information, including grants management, data acquisition and sharing, and accountability for resources. They help people organize IPM projects, create communications and learning forums, host webinars, moderate meetings, help state or local entities develop and disseminate information or whatever serves local goals. California Regional SPM Centers can play a similar role to expand and extend the knowledge base by such actions as follows:

  1. Reflect the continuum framework, i.e. chemical input-based to biological input-based to biodiversity-based farming systems,
  2. Research low-hazard and low-risk substitution tools necessary for transition,
  3. Facilitate community learning to integrate science, experience, and traditional and intuitive ways of knowing,
  4. Gather data for models that help teach the effects of agroecological practices on biodiversity and ecosystem services,
  5. Support learning for success in a biodiversity-based paradigm through seeing  the limits and false economies in the efficiency/substitution paradigm, 
  6. Facilitate learning that improves consultant and farmer decision-making in situations of uncertainty,  
  7. Improve communication between regulatory agencies and educators at public institutions with early engagement of educators of SPM in the decision process on aligned curricula and training of successful SPM practitioners,
  8. Include PCAs as active and respected players in the information pipeline especially in the area of field research, educational programs, and individualized grower assistance and follow up, and
  9. Showcase farms on their way to biodiversity-based systems that will attract added revenue from carbon and eco-credits. 

Among the opportunities with regional planning and programs, we’ll describe those that have not been discussed as much: Resource Conservation Districts, field scout training, regional food hubs and regional insectaries. 

Resource Conservation Districts are already a primary source of Technical Assistance and many employ people with backgrounds in agroecology and biodiversity conservation. There are 95 RCDs. Their boards of directors are from the region and tuned to local needs and resources. Their mission is natural resource conservation and learning how biodiversity-based farming systems support that mission through farmer-to-farmer learning and relevant farmer-directed research. They are an ideal focal point for stakeholders to consult and agree on strengths, needs, barriers and to make transparent decisions about how to distribute funding.

Wild Farm Alliance 2017 tool for organic farmers to work with RCDs to conserve biodiversity. 

Biological control field scout training is a needed area of development. Local colleges and universities, RCDs and the Cooperative Extension can collaborate to define the knowledge base for field scouts to monitor pest and natural enemy populations and apply biological control practices and tools, including installation and care of hedgerows, border plantings, interplantings, silvopasture, and agroforestry within an agroecological continuum framework. There are opportunities for inclusion and social equity values, for women, lower-income people, people of color, and especially farmworkers. Field scouting, like nursery work, is a path to employability in drug rehab programs. Some farmworkers have strong aptitude and desire to be field scouts. 

Francisco Cornejo Soms teaching Kevin Antongiovanni’s farm workers to scout for beneficial insects 1997

Regional food hubs are important for connecting farmers and ranchers with institutional buyers (restaurants, hospitals, schools, etc) and end consumers. They help farmers gain access to larger markets so they can focus more on farming and less on marketing, distribution, etc. Food hubs channel buyer needs and enable them to prioritize working with those farmers with organic or comparable certification. 

Regional insectaries have a long history in California. San Diego County Department of Agriculture was rearing Cryptolaemus for release into local lemon orchards at an insectary in Chula Vista in 1929 and other county insectaries followed. In the 1950s they were all funded by federal, state or county governments and then some by farmer cooperatives or pest control districts. The Fillmore Citrus Protective District (FCPD), a successful grower cooperative, had been formed to eradicate citrus pests, but an insectary to produce beneficial insects was added when the impracticality of eradication became evident. 

California State Insectarium. One of the world’s first insectaries built in 1907 at the capitol for collecting, breeding, and distributing beneficial insects to control fruit and vegetable pests. In 1923 most activities moved to the Citrus Experiment Station in Riverside.
Insect rearing cages in the state insectary over 100 years ago. . It is now a maintenance facility for Capitol Park in Sacramento.

Regional insectaries are an ideal focal point for collaboration in the training of both insectary workers and field scouts. Insectaries of the future must be grower-led cooperatives while benefiting from researchers to ensure uncompromised quality in biological control monitoring and interventions as well as products. In this model, regional cooperative insectaries can benefit the general community as well as farmers, assist with classical biological control projects, mass-rear and release augmentative biological control agents, and colonize and monitor released organisms. The membership of a regional insectary should democratically set priorities and plans about how to minimize toxic inputs, maximize grower economic sustainability, harmonize the urban-rural interface, and protect farmland. 

The ownership structure for regional insectaries best includes per acre member dues by growers, land-owners, and various districts, along with a financial contribution from local jurisdiction(s). The structure should have a check and balance on potential conflicting interests that may arise between insectary management, researchers and large growers. The manager must juggle the needs and strengths of a broad community of stakeholders to remain relevant and viable. All stakeholders must both inform and follow the lead of the  farmers, PCAs, farmworkers, and specialized agricultural workers and Field Scouts.  Grower-led regional insectaries are the way of the future. 

In my next post we’ll go deeper into how to teach and support Pest Control Advisors and field scouts to achieve biological control and help growers transition to less dependence on pesticides.  

Our Vision for Sustainable Pest Management – Part 4: Biological control action levels–examples from the field

by Ron Whitehurst, PCA and co-owner Rincon-Vitova Insectaries, Inc.

Pest Control Advisors (PCAs) make their decisions based on monitoring to determine an “action level” or “action threshold”. In other words, they look for signs that it is time to do something to prevent a serious pest problem. To align PCAs with the SPM goals, it is important that they understand the big difference between action levels for the conventional chemical input-based farms most of them are familiar with compared to farm systems that are either biological input-based, such as most organic acreage, or biodiversity-based. 

Treatment action levels on chemical input-based farms, of course, do not apply when chemicals are not an option. A new framework is needed for such farms. PCAs need training in determining “biological action levels”.  Entomology professor David Headrick asks his students at Cal Poly San Luis Obispo to think about two separate thresholds, one for chemicals and a different one for biological inputs. The following slide from his Biological Control class helps illustrate the need for early regular monitoring at low pest densities in order to time a natural enemy release to maintain the pest population at a low density. The timing of applications has to be carefully thought through. It is clear that the Economic Injury Level and the Chemical Control Action Threshold happen at a significantly higher pest density. 

Biological action threshold graph, Professor David Headrick, Cal Poly SLO Biological Control Course Lecture

As Dr. Headrick further explains, “Maintaining pest densities at low levels is most easily and effectively done with biological control agents. That is what they evolved to do – find prey when they’re scarce. It is also the most economically sustainable approach.”

Readers of “ACRES USA – A Voice for Ecological Agriculture” have been informed for decades about the potential for insects to find food and mates through subtle phenomena happening at low population densities. Dr. Philip S. Callahan, a regular contributor to ACRES USA, published Tuning In To Nature in 1975 describing experiments demonstrating insect behavior in response to low electromagnetic energies. He wrote, 

“A sick plant actually sends forth a beacon, carried in the infrared, attracting insects. It is then the insect’s role to dispose of this plant deemed unfit for life by nature…. Early in my career, I studied pesticides, as did all entomologists. But the findings I released…taught me that attempting to poison insects was at cross purposes to nature and would, in the end, prove futile.”

Biological control practitioners would never consider a biological action, such as releasing a few green lacewing larvae, when pest densities are high. Biological action levels must be earlier, at the first sign of a key pest in the season, when successful biological control is achievable. Consideration is also given to various cultural practices that minimize disruption of biological control. Long-range planning for habitat enhancement is another consideration.  Enhancing habitat in the long term can maintain pest levels at such low densities that monitoring does not need to be as in-depth or as frequent as field scouting shows no sign of reaching a biological action level. The focus of field scouting evolves to be more about continuing to enhance and monitor natural biological control.

Biological control entomology intersects not only with agroecology, including soil ecology, conservation biology and population dynamics, but also increasingly with molecular biology and insect-insect and plant-insect communication. Farmers and their Pest Control Advisors will need to be observant of population dynamics at the landscape scale and how insect and plant volatiles affect plant defenses and insect behavior. 

Dr. Joseph Patt with the USDA-ARS received doctorate degrees in both entomology and botany. His research on releasing parasitoid wasps for control Colorado potato beetle in eggplant led him to measure the accessibility of nectar in different potential habitat plants to make sure there was enough space in the floral architecture for the large heads of the wasps that the New Jersey State Insectary produced. Without nectar, the number of required wasps was unaffordable. By comparing 15 different plants and choosing to plant seed dill and coriander that have many flowers with open nectaries, he ensured adequate nutrition for wasp searchability and reproduction. This minimized the number of wasps that had to be mass-produced for a cost-effective program of one row of floral habitat every tenth row. Unfortunately farmers dropped the biological program when the EPA registered a new chemistry with Colorado potato beetle in eggplant on the label. Research funding in this area also disappeared. 

Diagrammatic representation in lateral view of the floral architectures on which E. puttleri and P. foveolatus were evaluated showing position of the nectar glands (in black) in relation to the other floral parts: (1) Umbels with exposed nectaries; (2) Cyanthia with exposed nectaries; (3) Umbels with partially hidden nectaries; (4) Cup- shaped flowers with partially hidden nectaries; (5) Capitula with hidden nectaries. Wasps are drawn to scale and are 3 mm long. Patt, et. al. 1997.

Many observations go into determining the presence of effective natural biological control. However, Pest Control Advisor training has been nested within a Production Agriculture curriculum, isolated from the sciences that explain population dynamics, and insect and plant physiology, biochemistry and electromagnetic communication to enhance biological control. To be aligned with SPM, the curriculum for PCAs must be equally nested within agroecology and the sciences that explain plant defenses and insect and mite behavior.

Dr. Headrick motivates his students to learn how to manage pests on regenerative organic farms by reminding them of the unsustainability of conventional chemical control. He tells them, “Chemicals are great for instant gratification, but not for long-term success in pest management.” This fact leads his students into the whole subject of pesticide resistance.

To be able to forecast whether population densities are approaching action levels, there is much to learn. Then, they have to be able to help farmers understand these concepts. Much research is needed for both areas of pedagogy. Scientists in France are developing learning models and games that teach decision-making about biological action levels. With such limited current training for PCAs, an entry level field scout requires at least two years of mentored field experience to learn basic skills to recognize action levels. Scouting in a variety of crops and farming systems is more challenging. It takes more years to be able to perceive the population dynamics and consider alternative cultural practices and cost-effective, manageable habitat enhancements and communicate with farmers to understand the options.

I enjoy those experiences when someone buys a rundown chemical farm and contacts me wanting to be organic. We start early in the fall to plan. I now know that measuring the upper and lower levels of compaction levels in the soil is critical to deciding on tillage. What characteristics are needed in a ground cover? Is good quality compost available?  Are ants likely to interfere with biological control? Where should this farm start with permanent habitat installations?

Early in the growing season there might be indications that one or more colonizations in perennial crops might help. Pest populations often stay so low that a biological action threshold is never reached and there is no need for augmentative releases or “treatments” with natural enemies. 

Here are a few examples to illustrate how biological control scouts determine a biological action level. 

Farm & location: Sanford, Santa Rosa Rd, Buellton

Size & farmscape: 12 acres between road and steep hillside, across the road from organic farm and Santa Ynez River, east-west river valley 16 miles from coast, diurnal breeze

Farming system, prior crop(s) & years in transition: at least a decade of chemical input-based lima beans, year 1 transition to organic

Crop(s) and key pest(s) & economic threshold: lima beans, two-spotted spider mite, in past would defoliate if not sprayed at least once, usually 3-4 times with conventional miticides

Cultural adjustments: none

Habitat enhancements: two interplantings ‘Beneficial Blend” with 20+ species plus weedy alfalfa, successional sweet corn, sorghum and sunflowers, perpendicular to prevailing westerly wind, 1) 30 ft from west end, 10 ft wide X 40’ long, 2) middle of 12 ac block, 10’ wide X 80’ long, 

Natural enemy colonizations: none

Monitoring method(s) and frequency: visual appearance of necrosis from spider mite damage, live mites and eggs, weekly across in 3-4 places and along perimeter 

Biological action level: monitoring showed the biological control from the interplantings protected most of the block except the south border on the east end  edges along the hill and drive road becoming infested; without natural enemy release, if there were hot, dry weather the mites could spread into the middle of the field protected by the biological control from the interplantings; mites could blow up requiring a spray to protect the whole block 

Action & result: two weekly releases of Galandromus occidentalis and green lacewing along the south border of the eastern half of the block brought the pest mites under control 

Farm & location: Dairy barn outside of Gunnison, Colorado

Size & farmscape: 10 cows, 1,000 sf open front, 3-sided, free-stall barn; manure moved daily to compost yard

Farming system, prior crop(s) & years of transition: organic cows over ten years

Crop(s), key pest(s) & economic threshold: houseflies annoy cows, reduce milk output

Cultural adjustments: more frequent clean-out, bucket trap near compost

Habitat enhancements: n/a

Natural enemy colonizations: monthly releases 10,000 fly parasites beginning at first sign of flies

Monitoring method(s) and frequency: 3X5 index “spot cards” counted weekly. Start with 4 cards and reduce to as low as 2 cards if counts are within 10%. Place one on the warm side and one on the cool side, one upwind and one downwind if there are differences.

Biological action level: average 100 spots/card, over 65’F so flies are active

Action & result: balEnce Fly Spray (beneficial fungus Beauveria bassiana) on surfaces; average spots/wk below 20.

Farm & location: Anonymous, Edna Valley, San Luis Obispo County

Size & farmscape:  Two fields separated by a seasonal creek: 40 acres and 35 acres, sandy loam soil.

Farming system, prior crop(s) & years of transition:  Standard, previously farmed as vegetables, conventional production, but no synthetic pesticides used.  I was hired to manage the crop start to finish using only biological control.  

Crop(s), key pest(s) & economic threshold:  Hemp for CBD, key pests:  western flower thrips, spidermites, noctuid caterpillars, botrytis.  CBD products are supposed to be made from plants without any pesticide residues and with as few contaminants as possible.  In this case having biological control agents on the plant surfaces at the time of harvest was deemed acceptable for the CBD extraction process.

Cultural adjustments:  Typical row crop approach, plastic mulch on beds, 40 inches on center, transplants at 2 foot spacing.  Transplants grown in a greenhouse from certified seeds.

Habitat enhancements: None.

Natural enemy colonizations:  In the greenhouse setting, the following natural enemies were released at standard rates so that they were actively foraging and reproducing on plants before they were placed in the field – a “pre-transplant inoculum”: Orius releases were made for thrips, Stratiolaelaps scimitus (Hypoaspis miles) was inoculated onto the transplant container soil surface for fungus gnats, lacewing eggs for whiteflies and small lepidoptera and Aphidoletes aphidimyza for aphids.  

In the field, subsequent releases were made based on monitoring.  Spot treatments of Neoseiulus californicus was made for spidermite control.  Bacillus thuringiensis was applied as a spray for caterpillar control.

Monitoring method(s) and frequency: Greenhouses were monitored with visual inspections, tap method and yellow sticky cards.  Monitoring was done once a week until plants reached about 8 inches tall, then twice a week until transplanted.  

Fields were monitored with visual inspection and beat sheet.  

Field monitoring was conducted once a week along rows, every 6th row but different rows each time, and always checking the first three upwind rows and two downwind rows each time.  

Biological action level:  All biological control agent releases (greenhouse and field) were made only if the target pest was present.  Thresholds were set “at first sight of pest”, with the idea that pests at low population densities are more easily controlled.  Most mite issues started on the upwind rows, predatory mites were applied as spot treatments.  N. californicus was chosen due to the hot, dry conditions and its ability to feed on prey other than T. urticae.  Bt sprays were applied to the entire field as soon as adult moths were observed being disturbed by the beat sheet monitoring methods.  Lepidopteran eggs were impossible to locate on the dense and trichome-laden foliage and flowers and waiting until feeding damage was readily observed was too late to gain control of the caterpillars.  The concern with caterpillar feeding was not so much the foliage, but the flowers.  When caterpillars fed in the dense flower clusters, they were virtually impossible to see and the feeding damage resulted in Botrytis infections.  Botrytis is a devastating fungal pest and will ruin a crop because it negatively affects the terpenoid extractions.  Closer to harvest, Bt sprays were conducted once a week as per the growers request.  

Action & result: I achieved excellent results with a 100% harvestable crop.  The greenhouse inoculation program was an effective and cost-efficient approach to having natural enemies evenly spread throughout the field and working on pest populations before full exposure to field conditions and new pest populations.  The approach of applying biological control agents on mature plants in the field can often lead to losing many of them during the process.  The Bt sprays were effective, but caterpillar control needs to be re-evaluated and diversified to avoid resistance.  Additionally, making spray applications on the dense flowers can itself lead to conditions that aid fungal growth.  Consistent, systematic, monitoring from crop onset and application of appropriate biological control agents when pest populations were extremely low was the recipe for success.  

Farm & location: Millennium Grove, Santa Paula, CA

Size & farmscape: 5 acres, landfill on long side

Farming system, prior crop(s) & years of transition: biological input-based;  sandy rocky, not organic

Crop(s), key pest(s) & economic threshold: Haas avocado (flowers Feb-May), persea mite; 8% leaf damage can cause defoliation

Cultural adjustments: 3-6 inches mulch, seaweed+high quality compost extract foliar 5X between Feb & June (flowering period), no artificial nitrogen or mineral fertigation 

Habitat enhancements: one “predator food station” every 8-12 trees, 1-2 stations/acre (with 12-20 plants of corn/acre (early, middle, late varieties planted monthly in April, May & June with Johnson grass and/or native creeping ryegrass or other grass with summer through fall flowering); maintain by watering each monitoring visit, cutting some bloom from grass patches when flowers are done to stimulate new flowering for continuous production of pollen blowing onto surrounding trees to maximize reproduction of predator mites

Natural enemy colonizations: none

Monitoring method(s) and frequency: spring & summer every other week, fall & winter monthly. Machlitt method: number of random leaves with one or more persea mite.  Number of Euseius hibisci  mites feeding on Persea mites on 50 random leaves 

Biological action level: Release N. californicus (Nc) predator mites by blower. Number depends on month, heat, humidity: 

  • April-June below 85’F, 25 leaves out of 50 w 1+ Persea, <10 Euseius: 100 Nc/tree first release
  • July-Sept below 85’F,  same levels as above: 150 Nc/tree first release
  • Forecast of Santa Ana winds (<10% humidity):same levels as above:  200-250  Nc/tree if first release
  • Forecast of heat wave over 100’F for 3+ days: no release since Persea die

Action & result: One June release of 100 Nc/tree resulted in <2% leaf damage; monitoring in August showed 15 Euseius/50 leaves; some corn and grass still producing pollen; Persea stayed below action level 

Millennium Grove. Trials of cover crops, grasses, weeds, and occasional corn hills to supply pollen to increase reproduction of predatory mites.

Farm & location: Christmas tree farm, Decatur, Illinois

Size & farmscape: 50 acres edge suburb, riparian native woodland east side, monocropped farm blocks three sides 

Farming system, prior crop(s) & years of transition: biological input-based Christmas trees for 20+ years

Crop(s), key pest(s) & economic threshold: 30 acres in Mugu and Scotch pine trees, pine needle scale, average 5 covered scales per needle on 10% of needles after pruning out the current year’s infested needles 

Cultural adjustments: Pruning infested branches

Habitat enhancements: permanent border of pine trees, mowed grass cover crop, one strip native flowering annuals per ten acres east-west

Natural enemy colonizations: none; Chilocorus lady beetles well established

Monitoring method(s) and frequency: double-sided tape around branch on warmest (south) side of tree, red nymph crawlers stuck on tape or on white paper on a clipboard when branch is hit over the paper once

Biological action level: average more than 1 nymph per tape or on white paper, release Lindorus lopanthae predatory beetles with 40/ac 1st release, 30/ac 2nd release two weeks later, and 1 or 2 more releases if crawlers continue to appear

Action & result: 2022 released total of 100 Lindorus per acre in four releases over 5 weeks during crawler emergence prevented development of noticeable armored scale


Patt, Joseph, George Hamilton, James Lashomb, 1997. Foraging success of parasitoid wasps on flowers: Interplay of insect morphology, floral architecture and searching behavior  Entomologia Experimentalis et Applicata, vol 83

Our Vision for Sustainable Pest Management Part 2: Defining how SPM actions relate to each other- Rev 9/23/22 

by Ron Whitehurst, PCA, and co-owner Rincon-Vitova Insectaries, Inc.


We sometimes hear people talk about “biologicals” as if the word is interchangeable with biological control. It is an example of lack of understanding about the full meaning of biological control in the transition away from conventional chemical control. Agreement on the vocabulary for agroecology, insect ecology and biological control is essential for productive conversations and successful pest management. 

We like to use definitions from Biological Control by Natural Enemies (1974) by Paul DeBach modified by Huffacker and Dahlston to include antagonists of plant pathogens. These align with those used by David Headrick, Professor of Agricultural Entomology, Biological Control of Agricultural Pests, Vertebrate and Insect Pest Management in the Plant Protection Science Program at Cal Poly San Luis Obispo. 

In a recent personal communication, Dr. Headrick wrote:

“Definitions are critically important, and I am particularly frustrated by the blurring of the lines on what is and isn’t biological control throughout the industry.  I agree with the definitions of biological control that you have provided below.  It is important to consider the difference between natural control and human-aided biological control, with biological control being the use of populations of natural enemies (imported or naturally occurring) to control or reduce populations of pests with various methods.”

Our mentor Deke’s understanding about biological control drew on countless hours of discussions over many years including on skin-diving trips. Here are UC entomology researchers Everett “Deke” Dietrick (l) with Paul DeBach (center) and Blair Bartlett (r), Moro Beach ~1948.

Our mentor Everett J. “Deke” Dietrick favored Paul DeBach’s terms and ideas. Deke, Paul, Blair Bartlett and a few other eminent biocontrol entomologists shared a love of not just biological control, but also enjoyed a long friendship and lively discussions while searching for the perfect skin diving cove between Laguna and Cabo Pulmo. Such conversations animated their lunch hour handball games at the Riverside Citrus Experiment Station (now UCR) as well as field trips including with Evert Schlinger, Robert van den Bosch, Fred Legner, Dan Gonzales, and others. This cadre of biocontrol entomologists helped Deke develop the clarity and confidence to leave the University of California and become the first consultant in California relying solely on biological control by natural enemies to manage pests.  This was before the invention of the term “IPM or Integrated Pest Management”. He called what he and enthusiastic consultant associates did for farmers “Supervised Control”. 

The birth of IPM and EBPM (Ecological-Based Pest Management) and the ‘Path of a Paradigm’ will be a later deep dive in this series for those interested in a sufficiently broad conceptual framework for talking about transition. But first, let’s agree on the terminology.   


Biological control, when considered from the ecological viewpoint as a phase of natural control, can be defined as the action of parasites, predators, and pathogens and antagonists in maintaining another organism’s population density at a lower average than would occur in their absence. [DeBach, 1974]

  • Note:  It can be measured, human manipulation is not implicit and it does not include plant selection for resistance to pests.  Biological control by natural enemies is central to transition from chemical input-dependent systems. When monitoring shows that there are enough natural enemies so that biological control is working, the complexity of phenomena may be too costly to measure and assess what actions are critical. The greater the biodiversity, the greater the complexity of interactions, the greater likelihood of a good ratio of natural enemy populations over pest populations. (See monitoring)

Applied biological control is the study, importation, conservation, and augmentation of natural enemies for the regulation of population densities of other organism’s abundance below the level of economic injury. Applied biological control can be achieved in differing degrees of economic importance which have been distinguished as partial, substantial or complete.

Natural control (sometimes called naturally occurring biological control) may be defined as the regulation of populations within certain more or less regular upper and lower limits over a period of time by any one or any combination of natural factors. [DeBach, 1974] 

Augmentative biological control is the mass collecting or rearing and release of natural enemies (predators, parasites and pathogens) to control pests in a timely seasonal or inundative manner to prevent population increases, or to suppress a pest population, sometimes called inundative releases to differentiate from colonizations.

Classical or importation biological control is the foreign exploration, importation and colonization of natural enemies of a pest of exotic origin that lacks natural enemies to suppress their populations. 

Conservation biological control is about conserving natural enemies either by reduction/elimination of toxic pesticides or enhancing/modifying the environment to invoke/enhance/supplement natural control.  

  • Note: This is a useful definition that covers all of the newer terms like ecological pest management in regenerative organic agriculture, farmscaping, biodiversity-based agriculture, and so on, that work by conserving biological control.  

Biological control monitoring consists of skills and tools to assess the ratio of the pest and natural enemy populations to indicate whether biological control is increasing or decreasing. Each farming and cropping system has relevant observable phenomena that can be identified, counted, recorded, and compared with samples from other sites or time scales. Sometimes visual inspection, sticky or pheromone traps are sufficient. Sometimes a sweep net is essential and sometimes a vacuum insect net is the only way to observe the presence of important natural enemies. Identification of organisms follows monitoring of the insect ecology. The required accuracy in counting sample contents and the precision in identification depends on the level of consequence for cost-effective decision-making. 

Biological action level is the density of key pests relative to the biological control at a particular stage in the crop cycle and the pest cycle that suggests that the application of one or more natural enemies will help ensure that the pest population stays below economic injury levels.

  • Note: David Headrick explains that the timing of applications of natural enemies, i.e. the biological control action levels, has to be carefully thought through and monitoring has to be more intensive than for chemical control action levels.

Economic injury level is the number of insects (amount of injury) that will cause yield losses equal to the cost of insect management – generally used for pesticide application decisions. 

Chemical action level or threshold is the pest density at which the pesticide application should be done to prevent an increasing pest population from reaching the economic injury level. 

Beneficial organisms in the context of SPM are predators, parasites, and pathogens and their antagonists contributing to biological control. The term does not typically include fish, amphibians, birds, reptiles, and mammals, but it can.

Natural enemies in the context of SPM refers collectively to all of the predators, parasites, and pathogens and their antagonists that reduce numbers of pest insects and mites, and may include fish, amphibians, birds, reptiles, and mammals, e.g. bats and other rodents. Organisms can have key roles as predators and may also transport beneficial parasites and pathogens in biodiversity-based farming systems. [UC-IPM

Biologicals are products derived from naturally occurring microorganisms, plant extracts, insects or other organic matter that may be categorized as 1) biostimulants to enhance plant growth and productivity, 2) biopesticides to protect plants from pests, or 3) biofertility or plant nutrition products.  

Note: A “biological” is an input whereas “biological control” is its larger sense a characteristic of the ecosystem. Biologicals are often products viewed as alternatives to chemical pesticides. They may still disrupt biological control by negative impacts on natural enemies.

Biopesticides are certain types of pesticides, 1) biochemicals, 2) microbials, and 3) Plant-Incorporated-Protectants (PIPs) derived from such natural materials as animals, plants, bacteria, and certain minerals.  [US-EPA] 

Biological control entomology is the applied branch of zoological study dealing with  insects and loosely including other arthropods (e.g. spiders and mites) for the purpose of controlling pests through conservation, importation, colonization and augmentation of beneficial organisms. Biological control deals principally with insects because most pest species are insects and most insect pests have natural enemies.

Biological control phytopathology and entomo-pathology are branches of study dealing respectively with the interaction between pathogens and plants and between pathogens and insects.

Biodiversity-based farming systems rely on re-designing the site-, space-, and time-specific practices and production approaches to create a high biological diversification and intensification. It is knowledge-intensive with outcomes of greater productivity and fertility from less exogenous inputs, and greater resilience to external impacts. This approach introduces a paradigm shift in expectations. It requires integration of interconnected processes, including influences of chemicals and/or low and very low short low-frequency waves, as well as integration of organization levels in ecological systems, such as landscape level populations and communities. [Duru, et. al. 2015]

Biological input-based farming systems rely on external biological more than chemical inputs to increase efficiency in combination with incremental substitution changes or system adaptations, such as organic fertilizers, and low-risk biological and botanical pesticides that mimic natural phenomena in biodiverse agroecosystems. This approach may integrate conservation, colonization and/or augmentation biological control [Duru, et. al. 2015]

Chemical input-based farming systems rely on external chemical inputs and technologies for improved efficiency and yield, that often include the use of Haber-Bosch-based nitrogen, potassium, and phosphorus fertilizers and chemical pesticides that optimize yield while limiting pollution. This approach may integrate conservation, colonization and/or augmentation biological control. Prohibition of nitrogen run-off may lead to use of cover crops in sensitive areas or in landscape features to prevent water pollution. Larger farm sizes and economies of scale may be required to afford the cost of technologies, such as sensors, spray equipment with targeting ability, drones, robots, satellites, cultivars and animal breeds. [Duru, et. al. 2015]

Efficiency/substitution approaches are economically driven practices within a chemical or biological input-based farming system. They are often top-down, developed by companies selling products or advisors that have evaluated products to meet expectations of greater profits by greater efficiency and use of technologies and innovations that reduce costs. [Duru, et. al. 2015]

Integrated Pest Management (IPM) IPM is an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and nontarget organisms, and the environment. [UC-IPM]

Sustainable Pest Management (SPM) is an agroecological approach within a spectrum of continual improvement to prevent, minimize, and manage pests in ways that protect human health and are environmentally sound, socially equitable and just, and economically viable. Pests are managed by combining biological, cultural, physical (including the use of new technologies that can improve detection, precise interventions, and plant resistance to pests), and, only when absolutely necessary, chemical tools, in a way that minimizes economic, health, and environmental risks.

Organic as a labeling term indicates that the food or other agricultural product has been produced by approved methods. USDA organic regulations require the application of a set of cultural, biological, and mechanical practices that foster cycling of on-farm resources, promote ecological balance, and conserve biodiversity. These include maintaining or enhancing soil and water quality; conserving wetlands, woodlands, and wildlife; and avoiding use of synthetic fertilizers or pesticides, sewage sludge, irradiation, and genetic engineering.

Regenerative agriculture has been called a land management philosophy. It involves the development of biodiversity-based farming systems focused on agroecological principles and practices that 

  • minimize soil disturbance; 
  • cover soil by mulching and multi-species cover crops or pasturage to prevent erosion and minimize weed growth; 
  • rotate crops to increase nutrient cycling, soil fertility, and water retention; 
  • increase plant diversity to conserve wildlife, pollinators and biological control and  increase soil microbial abundance; 
  • keep living roots in the soil as much as possible to protect soil microbes and retain water and nutrients; and, 
  • integrate animals into the farm as much as possible that adds nutrients and builds soil organic matter.

It draws on knowledge from agroecology,  agroforestry, organic practices, and holistic and rotational grazing. It offers increased yields and profit, improved watersheds, and enhanced ecosystem services, such as restoration of small water cycles, carbon drawdown and potential for accreditation for carbon and “eco” credits, resilience to climate instability, and better health and vitality for farming communities.

Regenerative organic encompasses organic farming and then raises the bar, prioritizing building soil health as a way to fight climate change. A holistic system, regenerative organic sees the well-being of earth, humans and animals as interconnected. High standards for animal and worker welfare are critical. It does not mean that the farm has Regenerative Organic Certification; it means that the farm is striving to apply these principles. [Patagonia Provisions]

Regenerative Organic Certification (ROC) is a label that can be added to organic certification for farms that meet higher standards in three areas: Soil Health & Land Management, Animal Welfare, and Social Fairness. Producers can choose to meet a beginning set of criteria (Bronze), an intermediate (Silver) or the highest achievable level of regenerative organic production (Gold). There are additional fees for ROC certification.

Real Organic Project (ROP) is a label that can be added to organic certification for farms that grow their plants in healthy, living soil and raise their animals humanely and on pasture to help consumers differentiate farms that are growing their animals and crops to both the letter and spirit of the certified organic standards. There is no fee for ROP certification.

Demeter Biodynamic Certification is a label that indicates that a comprehensive organic method has been used that requires the creation and management of a closed system minimally dependent on imported materials, and instead meets its needs from the living dynamics of the farm itself. The standard reflects the characteristics  of biodiversity-based farming systems. There are fees to become certified.


DeBach, P., Biological Control by Natural Enemies, Cambridge University Press, 1974.

Duru, M., Therond, O., Martin, G. et al. How to implement biodiversity-based agriculture to enhance ecosystem services: a review. Agron. Sustain. Dev. 35, 1259–1281 (2015).

Huffaker, C.B. and D. L. Dahlsten, “Scope and Significance of Biological Control”, in Bellows, T. S. and T. W. Fisher, Ed: Handbook of Biological Control, Academic Press, 1999.


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