W4185: Biological Control in Pest Management Systems of Plants

(Multistate Research Project)

Status: Inactive/Terminating

W4185: Biological Control in Pest Management Systems of Plants

Duration: 10/01/2017 to 09/30/2022

Administrative Advisor(s):

NIFA Reps:

Statement of Issues and Justification

Biological control continues to be proven one of the most effective, environmentally sound, and cost-effective pest management approaches used to controlling arthropod and mite pests. It will play an increasingly important role in integrated pest management (IPM) programs as broad-spectrum pesticide use continues to decline. Moreover, biological control is a cornerstone of organic farming, and the production of organic commodities in the United States continues to increase. Organic farming is no longer considered a cottage industry and has shown an increase in retail sales of nearly 300% since the recording began in 2002. The total retail market for organic products is now more than $39 billion in the United States alone (USDA Office of Communication Release 2016). Biological control is the "the action of parasites, predators, and pathogens in maintaining another organism's density at a lower level than would occur in the absence of the natural enemies" (DeBach 1964). Two types of biological control, natural biological control and applied biological control are often distinguished. Natural biological control is that brought about by indigenous natural enemies in the native range of a pest species. In contrast, applied biological control is achieved through human efforts or intervention, and consists of three main approaches; importation, augmentation, and conservation. In the importation approach (generally referred to as classical biological control), exotic natural enemies are imported and released in a new area where the target pest occurs, while augmentation and conservation involve supplementing (or manipulating) natural enemies already in place, or modifying the environment, respectively, to improve the effectiveness of biological control. For a given arthropod pest or weed, a pool of natural enemies often exists which consists of vertebrates, invertebrates, and microorganisms. The fundamental problem in applied biological control is to select an appropriate species or combination of species from this pool that will bring about the desired level of pest suppression with minimal impact on non-target species. It is difficult to put a monetary value on the savings due to biological control for many reasons, but potential benefit: cost ratios favor using these methods as a pest control option (Naranjo et al. 2015). The mission of this regional project is to facilitate research and implementation activities among the participating institutions and organizations in applied biological control.

This application is a renewal request for regional project W-3185 and involves biological control of both arthropod pests and weeds. Because biological control of arthropod pests and biological control of weeds are based upon many of the same ecological principles, researchers from the two fields benefit greatly from information exchange and research collaboration. Whereas the methodologies for controlling arthropod pests and weeds may differ, the scientific issues (e.g., introduction strategies, genetics of colonization, evaluation of natural enemy impact, etc.) overlap to a great extent. That some individuals involved in this project conduct research in both arthropod pest and weed systems is further evidence of the conceptual similarities between these two fields.

IPM programs based largely on biological control are of great benefit to agriculture, the quality of rural life, and the consumer. During the past decade, the USDA strengthened its commitment to pesticide reduction with its National Road Map to Integrated Pest Management. Reductions in insecticide and herbicide applications should allow farmers and ranchers to reduce production costs and make adjustments for a more sustainable agriculture. Reduced pesticide use will enhance the quality of rural life by decreasing ground and surface water contamination, reducing effects on non-target species (including honeybees and wildlife), and increasing safety of farm workers and other rural residents. These benefits also accrue at the interface of urban and agricultural environments, where there is increasing opposition to pesticide use by stakeholders. As an example of research involving W-3185 members contributing to effective IPM programs, biocontrol programs leading to the control of invasive pests of Eucalyptus in California have cost US$2,663,097 in extramural grants and University of California salaries. However, with the total value of eucalypt street trees in California ranging from more than US$1.0 billion to more than US$2.8 billion, the return derived from protecting the value of this resource through the biological control efforts, per dollar expended, ranged from US$1,070 for the high estimated number of trees to US$428 for the lower estimate. The analyses demonstrate both the tremendous value of urban street trees, and the benefits that stem from successful biological control programs aimed at preserving these trees (Paine et al. 2015).

Background Information and Justification: Despite many advances in recent years, our practical and conceptual understanding of success and failure in applied biological control fall short of meeting certain current and future requirements. For example, in classical biological control, the rate of establishment of natural enemies is relatively low in the case of arthropod pests (ca. 34%) (Kimberling 2004); further research into the genetics and ecology of colonization is clearly warranted. In the future, classical biological control should ideally be able to predict (1) the appropriate species (or biotype) or combination of species (and/or biotypes) to release for control of a target pest in a given situation; and (2) the environmental impact resulting from the introduction of an exotic enemy. Non-target impacts to plants or insects from biocontrol agents are of great concern to conservation biologists, environmentalists, and federal agencies. Since 2000, regulations on natural enemy importation and introduction have been enforced by the USDA-APHIS, using guidelines from the North American Plant Protection Organization (NAPPO) that require researchers to provide in-depth studies complete with rigorous data on the non-target effects of biological control agents they wish to release (Mason et al. 2005). Currently, non-target testing and regulations involved in releasing biological control agents continue to be important topics discussed routinely by this workgroup. As of this draft submission, the workgroup is still awaiting the proposed new regulations (330) from USDA-APHIS which will have changes that will impact applied biological control in North America. The W-3185 members receive updates routinely via email on many issues that affect biocontrol and when these proposed new regulations debut they will disperse the information and provide input to APHIS before the deadline. The W-3185 has always enjoyed the attendance and participation by Federal representatives from all the agencies that affect the movement and regulation of natural enemies. We are fortunate that these individuals attend, give presentations, and interact with our members each year.

We continue to increase our understanding of the ecological mechanisms by which a successful natural enemy operates in nature, and why a particular organism is successful in one situation and not in another. Where success has been achieved in classical biological control, the underlying ecological mechanisms are not always clear. Basic research on augmentation and conservation of natural enemies is also needed. In augmentation, we urgently need a coherent theory of inundative/inoculative release as well as basic efficacy data in order to more readily incorporate commercially available predators and parasitoids of arthropod pests into IPM systems. The genetics of mass production must be evaluated experimentally so that quality control procedures can become a regular practice in the commercial product, and this is ongoing for some past problematic species (Guzmán-Larralde et al. 2014). Advances in the nutrition of parasitoids and predators are needed. Continued commitment to conservation of natural enemies is required, including innovative ways of integrating pesticides and cultural controls with key natural enemy species. Global warming has long been accepted as an official threat to our natural and agroecosystems. The National Oceanic and Atmospheric Administration (NOAA) released information showing the year 2016 as the hottest since data has been recorded (1880), and the trend is not expected to reverse (NOAA, National Overview – Annual 2016). Recent studies predict that the abrupt rise in atmospheric carbon dioxide and global temperature may lead to increases in the amount and diversity of insect damage to plants, the shift of species host ranges, and alteration of life cycles (Schauberger et al. 2017). It will be imperative that biological control scientists watch for the effects of climate change on arthropod pests that have been kept in check by natural enemies (Crowder & Harwood, 2014). Products of biotechnology designed for pest control must also be assessed when incorporated into IPM programs. In the past five years, W-3185 scientists have examined interactions between transgenic crops and biological control species, and these studies will increase as more such crops are approved. Finally, the relentless pressure of invasive species arriving without their natural enemies and impacting both natural and agricultural ecosystems has management professionals requesting more environmentally friendly and effective tools. Overall estimates of the economic impact of invasive species are difficult to determine, especially when considering the impact to ecosystem benefits, but the most highly cited source estimates invasive species (as a whole) cost the U. S. alone more than $120 billion annually (Pimental et al. 2005). In 2011, the U.S. Dept. of the Interior spent $100 million on invasive species prevention, detection, research, international cooperation, and habitat restoration (USFWS http://ww.fws.gov January 2012). Continued impacts will be accrued in the coming years, as data indicate higher numbers of intercepted and established alien species each year. Accomplishments show that W-3185 scientists are working on many of these damaging pests using a multistate approach and international cooperation for foreign exploration and non-target testing.

Regional Character of Project: Exotic pests continue to arrive in the western U.S., and many of these will become permanently established. For such pests, the use of classical biological control should remain a high priority. At the same time, our IPM programs must be continuously evaluated, refined, and adjusted in response to changes in newer and more specific control technologies and production practices. The most effective way to address these new pests that become quickly established and spread to other states is through regional collaboration of state and federal scientists. Experiment Stations and non-Land Grant institution members to this project accrue timely and relevant benefits to participation. Regionality is essential to implementing biological control-based solutions to our pest problems for the following reasons: 1) numerous target pests occur in three or more western states or territories; for these pests, the research effort must be coordinated and duplication minimized to effectively utilize very limited resources; 2) regional importation/quarantine facilities are critical for a coordinated response to exotic arthropod pests and weeds. These facilities are finite, there are no plans to expand them in the foreseeable future, and they serve the needs of all states and territories in the region; and 3) interstate exchange of information and exotic species/biotypes is facilitated through a regional approach. Sharing the cost of foreign exploration and quarantine is essential, as is sharing of methodological advances and our knowledge base. Without a regional project in biological control, the western states and territories will not be able to rapidly share current information on controlling new and existing pest species, many of which have ranges over multiple states. Additionally, this group discusses emerging pest threats and forms collaborations and networks that anticipate and plan for pest arrival. Besides state to state (Experiment Station) collaborations, active participants include scientists from USDA-ARS, USDA-APHIS, USFS, and state departments of agriculture, all of which benefit from rapid information transfer and shared projects.

Advances in regulatory policy, general methodologies for release and evaluation of natural enemies, and the need to develop sound ecological theory concerning pest population dynamics, predator-prey interactions, and the genetics of colonization in biological control, are all fundamental needs in addition to coordination and cooperation of research on a given pest. For example, theoretical and experimental studies of the actual ecological mechanisms that underpin pest population regulation are being addressed in several states and among pest systems. Our members and Federal Advisers, serve on key committees that are steering efforts to minimize non-target effects through policy management, and a website (http://ucanr.org/sites/W-2185/: note, the University of California server that maintains this site cannot change the W number) serves to maintain real-time communication and continuity in this group of scientists that include members outside the western region.  

Related, Current and Previous Work

Related, Current and Previous Work

Over the past 5 years, new pests have arrived in the western U.S., and others have gained in importance, so these have been incorporated into a revised species target list [Appendix A].

Twenty one arthropod pests have been added to the work list, (minimum of 86 arthropod pests), and 4 new weeds (minimum of 54 weed species). A notable new pest to the western region now is the Asian citrus psyllid, which has devastated citrus in Florida and has now spread west to California. Beetles, scales, and other categories have all added new species to the region during the past 5 years. Weed categories of brassicas and grasses have both added pest species. 

Previous work (2012-2016): Substantial progress was made in the utilization of biological control for the suppression of both arthropod and weed pests through introduction (classical), conservation, and augmentation approaches. Measures of progress for the W-3185 group detailed in Appendix B include 581 professional publications produced as a result of research conducted under project objectives. These breakdown as follows; 507 peer reviewed journal articles, 12 technical papers, 26 book chapters/contributed sections, 2 books, 21 proceedings papers, Masters theses, and trade journal articles. This list is a conservative reporting of the overall output, as many members did not include their trade, proceedings, theses, and extension publications when reporting productivity.

Other measures of progress are the impact of the research on managing invasive and native pests, and fundamental biological discoveries, or changes in conceptual frameworks that influence biological control research. The past 5 years has also seen the continued development of new methods that influence how biological control research is conducted. Underlying these many accomplishments were the critical interactions and collaborations that transcended state and institutional boundaries and were made possible through this regional research project. Of the peer-reviewed publications for this group, 69 were co-authored by W-3185 members working together from different institutions. Many of the biocontrol programs on weed species covered under this project depend on the collaboration of researchers in several states at any given time, and many of these work hand in hand with an overseas W-3185 partner, CABI Biosciences. One example of this is the successful Russian knapweed program that has involved CABI and personnel in Wyoming and Montana.

The detailed research accomplishments by W-3185 scientists from 2012-2016 are presented in condensed form in the annual reports. The group is simply too large, and the accomplishments too diverse, to present these findings in detail below (W-3185 participants work on approximately 140 different pest species). Impact Statements summarize findings in Appendix C. Therefore, selected projects representing the contributions of many members are highlighted below.

Pest management impacts. Substantial impacts were made on many pests targeted in the previous period. Well over one million (individuals) were released or relocated for use against at least 25 pest arthropods or weeds in western states. Many more programs are evaluating non-target effects of potential biological control agents and applying for release permits. Additionally, these ongoing projects are assessing environmental consequences of former releases and documenting ecosystem impacts. Examples from the past 5 years include: 1) reduced pesticide use in potatoes led to higher densities of predatory bugs and better biocontrol of spider mites, 2) gall wasp releases against Russian knapweed in Montana were so successful, releases are extended to six additional western states, 3) a leafmining fly was finally determined to be host specific to arundo and is now the third biocontrol agent to be approved for release against this weed, 4) because a parasite of the cereal leaf beetle was found to have a strong dispersal ability, growers can be advised not to spend time and money introducing the wasp into newly planted field in Utah, 5) successful establishment of P. spegazzinii on the weed, Mikania in Guam will reduce the use of herbicides against this invader , 6) field and lab work evaluated host plant specificity of the eriophyid mite A. solstitialis against yellow starthistle, 7) a shoot tip-galling fly was released as the first biocontrol agent in the world targeting the invasive vine, Cape-ivy, 8) crop-specific predator conservation plans were developed with respect to fire ants and Geocoris spp., results being helpful in devising landscape-level biocontrol programs for stink bugs, 9) biological control of the Erythrina gall wasp appears to have successfully prevented the extinction of the native tree, Erythrina sandwicensis, a keystone species in Hawaii’s few remaining threatened lowland forest ecosystems, and 10) a classical biocontrol program has now been outlined in California targeting the brown marmorated stink bug.

Development of the conceptual framework for biological control research. Several projects involving development or tests of theory provided new insights in basic biology, or improved our understanding of the evolutionary relationships between groups of pest or natural enemy groups. One project showed that the induced effect of one weed biocontrol agent can result in positive or negative effects on other agents, influencing the net impact of biocontrol on weeds. This research provided a protocol for assisting practitioners in making decisions on whether to introduce more than one biocontrol species. The importance of natural enemy evenness (equitable relative abundances) is an understudied component of biodiversity, but was shown to make an impact in natural enemy conservation for controlling pests on pea, potato, Brassica, and tree fruit crops. Studies showed that mechanical damage to yellow starthistle led to production of volatile organic compounds that altered the behavior of a generalist predator slug and specialist herbivores, suggesting that plant manipulation of volatile signals might determine the extent of biocontrol damage. The need for increased biocontrol of legacy pests has been highlighted. Legacy pests are non-native but have been in the system for more than 25 years. They tend to not be researched for classical biocontrol and are now considered “naturalized”, but many still cause significant and persistent crop losses. Looking at sensory cues used by predators to locate prey is allowing for better predictions of predator foraging efficiency. A very interesting project showed a positive relationship between the invasion of arundo (giant reed) and the cattle fever tick. This work led to the development of the “pathogenic landscapes” concept and showed how successful biocontrol of an invasive weed can reduce the pathogenic potential of the invasive tick. Lastly, conceptual advances in the systematic relationships of various important pest and natural enemy groups will enable more effective and safer implementation of biological control. These groups include Leucochrysa, a green lacewing genus, assassin bugs (Reduviidae), a neglected group of potential natural enemies, and the important chalcidoid parasitoid groups of the Aphelinidae and Trichogrammatidae.

New methods. W-3185 researchers continue to lead in the development and use of cutting edge tools in biological control. New methods include the development of host range testing protocols for arthropod natural enemies in many current projects. Molecular techniques, including molecular genetics, are making huge impacts on biological control. Molecular diet analysis was used to show impacts of predatory insects and also of birds on herbivorous pests of Brassica crops. Molecular genetics work helped distinguish 9 species of Trissolcus wasps reared from eggs of brown marmorated stink bug; showed that wheat stem sawfly is native to North America and not an invasive alien; used Sanger-sequencing and novel anchored enrichment approaches on parasites of the fire ant; helped distinguish cryptic species complexes on biocontrol agents of leafminers in citrus; used PCR-based methods to investigate prey range of assassin bugs and other natural enemies in California; and is instrumental in helping with the maintenance of the “genetic quality” of a parasite for the Asian citrus psyllid.

Our knowledge of endosymbiont infections, and how they are affecting biological control agents, is the result of W-3185 researchers collaborating in several institutions, and are considered world leaders in area of study. Even new methods of collecting and analyzing relevant data, ecoinformatics, are being used to assess the effectiveness of biological control within IPM programs. Experimental, observational, and ecoinformatics-based approaches may, if used together, provide more efficient solutions to problems in pest management than can any single approach, used in isolation. Novel multivariate ordination methods have allowed researchers to comprehensively assess and quantify the impact of potential environmental stressors on the entire natural enemy community. The approach has been used to evaluate insecticide selectivity in large field studies and assess the risk of transgenic crops to non-target arthropods such as predators and parasitoids. W-3185 scientists are leading many of these technologically-progressive projects.

Outreach. Many project members made contributions in biological control outreach. Outreach activities have included: 1) presentations, seminars, and workshops for growers, regulators, county extension personnel, and K-12 students on the risk of invasive species, 2) short courses to prepare biological control practitioners for licensing exams, 3) and training for quarantine personnel. Members do not traditionally list extension publications and presentations for annual reports, but examples from a few W-3185 members with extension time give an indication at how productive this group can be. As part of an NSF project, one team developed modules explaining parasitoids to HS students, Master Gardeners, and other public groups. They worked on outreach material to teach about parasitic Hymenoptera and their importance in biocontrol and biodiversity. Collaboration between USDA (CA) and the UC scientists provided educational opportunities for two foreign scientists and training programs for 9 students and early career professionals in the theory and practice of weed biocontrol. APHIS-PPQ workers in Micronesia have been trained in annual workshops. Increased participation by Guam Customs officers is heightening awareness of the threat to Guam by invasive species.

The W-3185 website continues to provide an anchor of updates on meetings for this working group, as well as an information-intensive site for research results. It includes web links to all members and collaborators, posts individual annual reports by institution, background information on biological control in general, and all annual meeting agendas and subsequent presentations. PDF files of detailed progress reports provides a wealth of information to our stakeholders on W-3185 research output, and also serves as a communication vehicle to W-3185 members and institutions.

Areas Needing Further Investigation. Biological control programs require a) identifying a country of pest origin, b) locating and successfully importing a natural enemy, c) rearing the natural enemy and testing for non-target impacts, d) applying for release of promising agents and waiting for approval, and finally, e) releasing the agent and evaluating field efficacy. These steps take time and additional work needs to be done on most of the pest groups for which current research is ongoing. This group is very instrumental in the development of procedures for host range testing of arthropod natural enemies. Symposia sections during the W-3185 meetings discuss specific on-going cases and debate the details of how to perform non-target testing.

An invaluable function of W-3185 to the western region is information exchange on emerging pests. Many W-3185 participants operate globally, engaged in foreign exploration, speaking at international symposia, and collaborating with scientists in other states and countries. This group provides a network of resources with which to anticipate and plan for the inevitable arrival of an arthropod or weed pest that will appear without its natural enemies. In addition to the yearly meeting, an extensive email list is maintained of the members and many other biological control scientists and regulatory personnel. Timely information on regulations, annual meetings, job vacancies and more are sent whenever appropriate.

The regulatory structure for classical biological control programs continues to be an issue that impacts everything from foreign exploration to the release of natural enemies that have been thoroughly screened for non-target impacts. In the past 5 years, lengthy delays before permitting, rules prohibiting hand carrying of biological control organisms, problems with shipping live organisms worldwide, and other regulations mandated by the Department of Homeland Security, continue to significantly constrain project research. While we support regulation promoting environmentally sustainable and ethical practices in biological control, we also strive to maintain research projects that will control devastating arthropod and weed pests. In the past 5 years we have addressed these concerns at our annual meetings, and worked with our National Program Leaders in biological control in USDA-ARS, USDA-NIFA, and USDA-APHIS-PPQ to resolve these constraints. We intend to continue to be a voice for a regulatory process that provides the needed oversight of biological control research to ensure it is safe and effective, but does not impede progress on what is often the most ecologically benign method of pest suppression.  


  1. Goal A: Import and Establish Effective Natural Enemies (Classical Biological Control)
    Comments: Objective 1. Survey indigenous natural enemies. Objective 2. Conduct foreign exploration and ecological studies in native range of pest. Objective 3. Determine systematics and biogeography of pests and natural enemies. Objective 4. Determine environmental safety of exotic candidates prior to release. Objective 5. Release, establish and redistribute natural enemies. Objective 6. Evaluate natural enemy efficacy and study ecological/physiological basis for interactions.
  2. Goal B: Conserve Natural Enemies to Increase Biological Control of Target Pests.
    Comments: Objective 7. Characterize and identify pest and natural enemy communities and their interactions. Objective 8. Identify and assess factors potentially disruptive to biological control. Objective 9. Implement and evaluate habitat modification, horticultural practices, and pest suppression tactics to conserve natural enemy activity.
  3. Goal C: Augment Natural Enemies to Increase Biological Control Efficacy.
    Comments: Objective 10. Assess biological characteristics of natural enemies. Objective 11. Develop procedures for rearing, storing, quality control and release of natural enemies, and conduct experimental releases to assess feasibility. Objective 12. Implement augmentation programs and evaluate efficacy of natural enemies.
  4. Goal D: Evaluate environmental and economic impacts and raise public awareness of biological control.
    Comments: Objective 13. Evaluate the environmental and economic impacts of biological control agents. Objective 14. Develop and implement outreach activities for biological control programs.


Goal A: Import and Establish Effective Natural Enemies.

Objective 1: Survey indigenous natural enemies. The scientific literature will be reviewed to determine prior records and geographic distributions of potential natural enemies of arthropod pests and weeds. A survey and collection of natural enemies will be conducted throughout the geographic area of infestation of each target pest. Parasitized pests and natural enemies will be held in the laboratory to allow natural enemy emergence, identification and determination of levels of parasitism and hyperparasitism. For herbivores, specific types of plant injury will be catalogued and plant species closely related to the target weed will be surveyed.

Objective 2: Conduct foreign exploration and ecological studies in native range of pest. The purpose of foreign exploration is to find, select, and obtain natural enemies from abroad which show promise as biological control agents. Ecological studies conducted on candidate natural enemies in their native range provide information that allows selection of the safest and most effective candidates, and facilitates their establishment and impact on the target pest in the U.S. Natural enemies will be collected and studied abroad in multiple locations throughout the native range of the respective pests. Live materials will be shipped to quarantine facilities listed under Objective 4 and will be shared among scientists/institutions as discussed under Objective 5. The overseas activities will be conducted by a) U.S.-based federal and state scientists from this project; b) other federal and state scientists based at domestic and foreign laboratories; c) scientists participating in USDA programs for exchange of science and technology with countries such as Japan, China, and Russia; and d) scientists operating under contracts with overseas institutions such as BBCA (Italy), and CABI Biosciences (Switzerland). The network of foreign cooperators that project scientists collaborate with is extensive, and provides critical support in foreign exploration efforts.

Objective 3: Determine systematics and biogeography of pests and natural enemies. Correct identification of a target pest and associated natural enemies provides a link with the work carried out in the past and represents a key to obtaining information in the scientific literature on biogeography, ethology, and ecology of a species. Many target pests and natural enemies belong to systematic groups that are in a state of taxonomic confusion, and some groups are only now being modernized. Detailed systematic studies of target pests and natural enemies will involve modern taxonomic approaches including molecular, biosystematic, morphometric, and numerical taxonomic techniques. Initial analysis of the biogeography of target host and natural enemy species will be based on results of geographical surveys and information in the scientific literature. It is noteworthy that this regional project contains scientists with systematic and molecular genetic expertise in many of the natural enemy groups critical to biological control. Expertise essential for natural enemy studies planned for the next five years is represented in the following participating agencies: CA-AES (Phytoseiidae, Coccinellidae, Encyrtidae, Braconidae, Aphidiidae, Pteromalidae, Reduviidae, Trichogrammatidae); ID-AES (Chrysopidae, Hemerobiidae, Coccinellidae); HI-AES (Encyrtidae, Eucoilidae); KS-AES (Encyrtidae, Aphelinidae); NMSU-AES (Pentatomidae); NY-CUAES (Chrysopidae, Hemerobiidae); OR-AES (Coleoptera, Mites, Heteroptera, Lepidoptera, Diptera); Guam-AES (Formicidae, Aphidae); and WA-AES (Chamaemyiidae, Syrphidae). Additional assistance is available through an extensive network of collaborators for taxonomic determinations among the Agricultural Experiment Stations, USDA, and other institutions (e.g., Bishop Museum, Honolulu; USNM; British Museum).   The USDA-ARS, EBCL (European Biological Control Lab) has a molecular laboratory involved in taxonomic and systematics research at various levels ranging from species to higher-level studies. 

Objective 4: Determine environmental safety of exotic candidates prior to release. The environmental safety of classical biological control has been called into question by conservation biologists and others concerned about the direct and indirect non-target impacts of exotic natural enemies. This has resulted in a need for more in-depth study of the environmental safety of candidate agents. Much of this additional work will be done in U.S. quarantine facilities (as well as overseas, see Objective 2). Traditionally, work in U.S. quarantines focused on exclusion of undesirable pathogens, parasitoids, hyperparasitoids, and predators from natural enemy shipments. Also, much host specificity testing of weed agents has been conducted in U.S. quarantines. With enhanced emphasis on assessing the environmental safety of candidate agents prior to release, U.S. quarantines will become an increasingly important resource and of vital importance to serving many of this projects objectives. Exotic biological control agents will be received, processed, and studied in quarantine facilities at CA-B-AES (Albany), CA-R-AES, HI-SDOA, WA-AES, WA-ARS, Guam-AES, MT-ARS, EBCL-ARS (France) for the management of arthropod pests. Biological control agents of weeds will be handled through quarantine facilities at CA-ARS, NMSU-AES, MT-AES, MT-ARS (NPARL), WA-AES, and HI-FS. A few projects will utilize quarantine facilities in other regions (TX-AES, USDA-APHIS-PPQ-CPHST /), DE-ARS, MD-ARS (Fort Detrick), VA-SDA, FL-AES). Quarantine and enhanced pre-release studies of environmental safety will be conducted for exotic natural enemies attacking pests in 11 target pest groups by 12 participating agencies.

Objective 5: Release, establish, and redistribute natural enemies. Key steps in the implementation of classical biological control are the initial release, establishment and redistribution of approved natural enemies. The initial numbers of natural enemies available for field release or redistribution are often limiting, requiring laboratory or field propagation. Facilities for mass production exist at CA-ARS, CA-DFA, CO-DOA, MT-AES, MT-ARS, WA-AES, and WA-ARS. There are also limited rearing facilities on Guam. USDA-ARS labs in Newark, DE and the USDA-ARS, EBCL in France also have the capacity to assist this group with mass rearing and mass field collections. Many weed biological programs initiate field insectaries that ultimately produce large numbers of individuals for redistribution. However, even with sufficient numbers for release, establishment does not always occur. Consequently, studies are being conducted by project members that examine various factors that might influence colonization. A noteworthy feature of this regional project is the high degree of natural enemy sharing among participants for initial release in new habitats and for redistribution.

Objective 6: Evaluate natural enemy efficacy and study ecological/physiological basis for interactions. The establishment of a natural enemy species does not always result in effective control of the target pest, as many ecological and environmental factors may influence the degree of control achieved. Hence, ecological studies must accompany the release of biocontrol agents to evaluate natural enemy impact, improve efficacy, and determine the ecological/physiological basis for natural enemy-host interactions. Experimental techniques used to quantify natural enemy efficacy include natural enemy inclusion, exclusion and interference. These consist of adding, excluding or interfering with natural enemies in experimental settings and comparing these to un-manipulated controls. Standard techniques will be used to study the influence of environmental variables (e.g., temperature and humidity) on life-history characteristics of the natural enemies and on predator-prey and parasite-host interactions. A key aspect of this regional project is that valuable comparative data from the wide range of habitats found in the Western Region is often obtained through collaboration among participants.

Goal B: Conserve Natural Enemies to Increase Biological Control of Target Pests.

Objective 7: Characterize and identify pest and natural enemy communities and their interactions. Two critical first steps in the conservation of natural enemies are determination of the identity of the species involved and characterization of the ecological communities in which they reside. This information is fundamental to developing an understanding of how perturbations such as pesticide applications will influence pest and natural enemy densities. Much of the methodology needed to address this objective is the same as for Objective 1.

Objective 8: Identify and assess factors potentially disruptive to biological control. Conservation biological control involves the alteration or modification of the environment to favor natural enemies, either by reducing adverse factors or by providing missing requisites. Thus, specific factors that impede or reduce the efficacy of biological control agents must be identified and quantified as to their impact. For many of the target pest species, this involves the identification of agricultural practices (mainly broad spectrum pesticide applications) that impact biological control agents, including the impact of herbicides on weed biological control agents. Many studies have focused on laboratory surveys and bioassays of various pesticides and subsequent large-scale field tests involving these "softer" compounds. Other factors, such as climatic extremes, indigenous natural enemies, cultural management practices, etc., can also be disruptive to the natural enemies.

Objective 9: Implement and evaluate habitat modification, horticultural practices, and pest suppression tactics to conserve natural enemy activity. As mentioned above, the conservation approach to biological control seeks to enhance the effectiveness of natural enemies, but may also target the pest as well. Examples of the conservation approach include maintaining weedy borders around fields or intercropping with nectar/pollen producing species to increase longevity and reproduction in the natural enemies; providing nesting boxes or shelters to improve reproduction or create refugia from environmental extremes; and using various agronomic approaches to increase the effectiveness of the natural enemies and/or hinder the target pest (e.g., plant spacing, cover crops, polycultures, strip crops, strip-cutting, crop rotation, trap crops, early/late planting and harvesting, etc.). These approaches may help conserve natural enemies while still controlling the target pest. The utilization of selective pesticides (especially microbials), including their selective use (e.g., reduced dosages and frequency of application, and selective timing of pesticide application) may help conserve natural enemies while still controlling the target pest. Research studies will focus on the implementation of these approaches and especially field-scale evaluation of the impact on host/prey diversity, natural enemy activity, and pest suppression.

Goal C: Augment Natural Enemies to Increase Biological Control Efficacy.

Objective 10: Assess biological characteristics of natural enemies. Natural enemy species and biotypes may show differences with regard to their biological characteristics (e.g., developmental thresholds and rates, fecundity, behavior, host specificity, cold tolerance, etc.) and these differences may influence their effectiveness as biological control agents. Research will be conducted to develop criteria for selecting biotypes, species, and combinations of beneficial species for use against a given pest to ensure that the most suitable natural enemy species are selected for each specific augmentative release program,

Objective 11: Develop procedures for rearing, storing, quality control and release of natural enemies, and conduct experimental releases to assess feasibility. The success of mass-rearing programs for experimental and commercial augmentation is highly dependent on the procedures used for rearing, storing, distribution, and release of natural enemies. Large-scale rearing of arthropod natural enemies usually requires the production of host plants, the arthropod host, and the natural enemy. Changes in colonies can occur due to genetic or environmental influences that can reduce the effectiveness of the natural enemy after release. Prior to release, it is desirable to increase the shelf-life of natural enemies for subsequent delivery and distribution. During storage, aspects of natural enemy quality such as viability and fecundity may be significantly reduced resulting in decreased efficacy of the biological control agent. Determination of the best natural enemy stage(s) for release and effective release methods are prerequisite for the timely suppression of the target pest. Research will be conducted to develop rearing and storage techniques for a variety of natural enemies for both inundative and inoculative release programs. Work will also focus on genetic improvement of natural enemies and assessing their value for pest suppression in various agricultural systems. Further, an understanding of the relationship between the numbers of natural enemies released, the resulting impact on the pest population, and the level of protection provided to the commodity is required. The development of management and economic models based on an understanding of such population processes will aid in characterizing the benefits of augmentation. Research will involve characterizing the interactions between the host, the natural enemies used in augmentation, and their biotic and abiotic environment, and will also include the development of optimal release strategies (i.e., timing of release, optimal numbers for release, rates of release, etc.).

Objective 12: Implement augmentation programs and evaluate efficacy of natural enemies. The successful suppression of pest populations through augmentative releases of natural enemies is often dependent on a clear understanding of appropriate times and numbers for natural enemy release, and mitigating problems associated with pesticide disruption or cultural management approaches that might be harmful to the natural enemies involved in the augmentation. Augmentation programs must be evaluated to determine the impact of the natural enemies on the target pest using different release strategies, or under varying environmental conditions. The economic feasibility of such programs also needs to be determined. Augmentative releases will be compared in small and large field trials with conventional control methods (e.g., pesticide applications) and untreated controls to assess natural enemy efficacy and the economic feasibility of such releases. Natural enemy exclusion or inclusion approaches may be needed to ensure that observed impacts are due to the inoculative or inundative releases, and not to indigenous natural enemies responding to more suitable conditions following the modification of agricultural practices (e.g., limited pesticide applications).

Goal D. Evaluate environmental and economic impacts and raise public awareness of biological control.

Objective 13: Evaluate the environmental and economic impacts of biological control agents. Although we as a community of scientists are well aware of the benefits of a successful biological control program, economic and environmental impacts are often not thoroughly evaluated. With community concern about potential negative impacts of biological control, it is more important than ever that both positive and negative environmental impacts be documented. Research will be conducted to determine patterns of non-target host utilization by natural enemies of weeds and arthropod pests, and the population-level consequences of non-target attack. Research will also be initiated to evaluate the genetic potential for specialized natural enemies to expand their host ranges. The evaluation of a natural enemy's potential for host range expansion will be accomplished by surveying closely related taxa or species that share the same or similar ecological niches to the target species. Field plots will be established in areas where the natural enemies are active or have been released, and the non-target hosts will be sampled periodically based on the life cycles of the organisms involved. If transfers are detected, the impact of the agents on the non-target host will be measured by determining the frequency, geographical, and taxonomic extent of attacks. The loss of growth and viable seed production (plants), rates of mortality, or changes in abundance of non-target host populations will be determined using replicated check and treatment plots coupled with exclusion or other appropriate techniques. Further, the economic return on research dollars spent on biological control is well known to scientists but not widely appreciated by the public. Declining resources and state/federal initiatives towards more accountability make it imperative that benefit/cost ratios of biological control be determined. Our charge in this objective is to carefully document benefit/cost ratios of biological control programs for both insect and weed pests. The costs of obtaining, processing, propagating, releasing, and evaluating introduced biological control agents will be obtained from the respective project records. Using treatment thresholds, the cost of chemical treatment or other control tactics will be determined by querying pest control operators, growers, or by determining the cost of materials, labor, and operation of the application equipment. Using the production values associated with the current land use, the economic and environmental benefits of biological control will be determined. The economic value of conservation and/or augmentation of natural enemies will be assessed along with the long- term costs of using the natural enemies. These costs will be compared with the economic inputs of alternative conventional control methods, or total absence of controls.

Objective 14: Develop and implement outreach activities for biological control programs. This objective seeks to encourage greater development of outreach programs among our participants as well as to document current outreach efforts that have not been easy to report under our current set of objectives. Well-documented, and highly visible outreach activities include 1) publication of our research findings in international journals, and 2) an outreach website. This W-3185 website has general information about biological control, a list of the contributing members to W-3185, their contact information and individual reports, project annual reports, and links to upcoming events, jobs and funding, and other relevant information. This web site will continue to serve as a public face to the W-3185 group. Less well-documented in the past have been talks to constituent groups such as grower groups, ranchers, forest managers, and Master Gardener groups, as well as the development of educational materials about biological control programs for the public can easily be added for public consumption.

Measurement of Progress and Results


  • The results of the proposed research activities will consist of: new or improved natural enemy species or biotypes for biological control of major arthropod and weed pests in the western U.S.; improved methodologies for incorporating biological control into IPM programs for key agricultural resources in the western U.S.; data addressing the ecological basis of success and failure of biological control; and data addressing the environmental and economic impacts of biological control. The publications, presentations and website will continue to provide the state and federal agencies, and grower industry clientele with both technical and practical information on a timely basis.

Outcomes or Projected Impacts

  • The availability of new or improved biological control options for major pest species in the western U.S. will result in reduced pesticide usage, increased sustainability of agricultural production systems, and economic benefits to both agricultural producers (in the form of reduced pest management costs) and consumers (in the form of reduced food costs). The attendant benefits of reducing pesticide usage include reduced food, soil and water contamination, reduced impacts on non-target species including wildlife, and reduced human exposure to potentially harmful chemicals. Enhanced knowledge of the ecological mechanisms underlying biological control will increase success rates. Enhanced knowledge of the environmental and economic impacts of biological control will improve the environmental safety of biological control and foster its adoption in current and new pest management programs.


(2022):The sequence of objectives for Goals A, B and C define a typical progression for classical, augmentative and conservation biological control programs, respectively. The numerous, specific biological control programs that comprise this proposal are at different points along these progressions. For the most part, initiation of Objectives 13 and 14 (Goal D) will require completion of Goals A, B and C.

Projected Participation

View Appendix E: Participation

Outreach Plan

Traditional outlets for disseminating project results, including peer-reviewed articles, annual progress reports, presentations at scientific meetings, websites created for specific projects, and extension publications and presentations, will continue to be heavily utilized. The publishing effort of this group is both prolific, and of very high quality. In the last five years, our group has published in excess of 581 publications [Appendix B]. A measure of multidisciplinary research, 124 peer-reviewed publications in the past 5 years have been in non-arthropod pest management journals. This effort will clearly continue. Our members do not list submitted and invited talks that do not include a proceedings paper, however, these would number in the upper hundreds over the past 5 years. The annual meeting of W-3185 members and collaborators is well-attended and includes presentations on timely projects. As an example, of the 50 attendees to the 2016 meeting, 14 Land Grant Experiment Stations were represented, and 12 different state or federal institution (separate locations) participated. The meeting also includes presentations by selected members on relevant topics organized into sessions each year by relevance. These are frequently sent to members via email after the meeting. Another goal for improving the website is to add impact/informational reports for the general public on high profile pests. While several participants have extension appointments, most also participate in extension and other outreach activities. A unique feature of biological control research is that many of the research activities are conducted in close cooperation with end users. This is especially true in classical biological control where large or multiple areas infested by the target pest are required when introducing new agents. Researchers work with public and private land managers to access these lands. For example, researchers in the saltcedar biocontrol program are cooperating with private, local (county weed departments), state (game and fish departments, water commissions) and federal agencies (USDI-NPS, BLM, BOR, FWS, USDA-NFS). Researchers working on conservation and augmentative biological control also work hand-in-hand with producers and other beneficiaries. The addition of a project objective (Obj. 14) for outreach has helped document both the formal development of outreach programs and the informal efforts of many participants to include constituent groups in their programs.


The Technical Committee will be comprised of representatives designated by the directors of various participating state agricultural experiment stations, state departments of agriculture, and federal agencies. This project is considered a Western Regional Research Project administratively, but because this regional project embraces research topics and biological control tactics of national scope and interest, participation by scientists from other regions of the United States is encouraged. The administrative advisor will be selected by the Western Association of Agricultural Experiment Station Directors and the advisor will serve the committee without vote. The Technical Committee officers will consist of a Chair, Secretary, and Representative at Large elected from the regional project membership. These elected officials, plus the administrative advisor, comprise the Executive Committee. The Chair will prepare technical and executive meeting agenda, preside at meetings, and prepare an annual progress report on the research activities of the regional project. The Secretary will record the minutes of technical and executive committee meetings and perform other duties as necessary. The Representative at Large, who will be elected annually, will succeed the Secretary, who will, in turn, succeed the Chair. The Technical Committee will meet annually, unless otherwise planned, at a place and on dates designated by majority vote of the Technical Committee members.

Literature Cited

Crowder, D. W., & Harwood, J. D. 2014. Promoting biological control in a rapidly changing world. Biological Control 75: 1-7.

DeBach, P. 1964. Biological control of insect pests and weeds, ed. P. DeBach. London: Chapman & Hall.   844 pp.

Guzmán-Larralde A. Cerna-Chávez, E., Rodríguez-Campos, , Loyola-Licea, J.C., & Stouthamer, R. 2014. Genetic variation and the performance of a mass-reared parasitoid, Trichogramma pretiosum (Hymenoptera: Trichogrammatidae), in laboratory trials. Journal of Applied Entomology 138: 346-354

Kimberling, D. N. 2004. Lessons from history: predicting successes and risks of intentional introductions for arthropod biological control. Biological Invasions 6: 301-318.

Mason, P. G., Flanders, R. G. & Arrendondo-Bernal, H. A. 2005. How can legislation facilitate the use of biological control of arthropods in North America? Proceedings, 2nd International Symposium of Biological Control of Arthropods, Davos, Switzerland. Sept. 2005. U.S.D.A. Forest Service Publication FHTET-2005-08, vol. 1. pp. 701-714.

Naranjo, S.E., Ellsworth, P.C. & Frisvold, G.B. 2015. Economic value of biological control in integrated pest management of managed plant systems. Annu. Rev. Entomol. 60: 621-645.

Paine, T.D., Millar, J.G., Hanks, L.M., Gould, J., Wang, Q., Daane, K.M., Dahlsten, D.L., & McPherson, E.G. 2015. Cost-benefit analysis for biological control programs that targeted insect pests of eucalypts in urban landscapes of California. Journal of Economic Entomology 108: 2497–2504.

Pimentel, D., Zuniga, R. & Morrison, D. 2005. Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics 52: 273-288.

Schauberger, B., Archontoulis, S., Arneth, A., Balkovic, J., Ciais, P., Deryng, D., Elliott, J., Folberth, C., Khabarov, N., Müller, C., T. Pugh, T.A.M., Rolinski, S., Schaphoff, S., Schmid, E., Wang, X., Schlenker, W. & Frieler, K. 2017. Consistent negative response of US crops to high temperatures in observations and crop models. Nature Communications DOI:10.1038/NCOMMS13931

USDA Office of Communication Release No. 0084.16. 2016. USDA reports record growth in U.S. organic producers.


Land Grant Participating States/Institutions


Non Land Grant Participating States/Institutions

Association of Natural Biocontrol Producers, California Department of Agriculture, University of California Santa Barbara, USDA-ARS/Arizona
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