Biological Control

Introduction

Biological control (or biocontrol) is a key component in establishing an ecological and integrated approach to pest management. We define biological control as the decline in pest density as a result of the presence of natural enemies. The degree of pest decline might be in the form of partial or complete pest suppression. We use the terms “natural enemies,” “beneficials,” and “biocontrol agents” synonymously to refer to predators, parasites, parasitoids, and diseases of pests. These different groups of natural enemies control pest populations in different ways. Predators and parasites are driven by food-seeking behavior, and control pest populations through predation. Parasitoids are driven by the reproductive need to use another insect as a host for its offspring to develop within, and control pest populations through reproductive pressure. Diseases are driven by infection pressure, and control pest populations through opportunistic outbreaks. How a natural enemy population responds to pest presence is critical to its efficacy.

Biocontrol is generally more compatible with organic and sustainable agricultural approaches than pesticide-dependent agriculture. This is especially evident when non-selective, broad-spectrum chemistries are used because biocontrol agents tend to be highly susceptible to non-selective pesticides. Even short to moderate pesticide exposure time may reduce their populations and allow minor pest insects that would otherwise be held in check to become major pest problems. The term “secondary pest outbreak” is used when this scenario occurs. A reduction in natural enemies can also contribute to dependence on further pesticide usage and result in a cycle of chemical dependency that has been called a “pesticide treadmill.”

Ideally, natural enemies reproduce on their own; their populations are self-sustaining, they are not harmful to the ecosystem, and they can be used in combination with other integrated control tactics. Natural enemies used in biological control can target a wide range of pest species (generalist) or a limited range of species (specialist). Generalist natural enemies such as predatory beetles can switch readily among alternative food or host sources. When target pest numbers are low, generalist natural enemies may maintain populations locally by consuming other prey species. Specialist natural enemies such as some parasitoid wasps have more restricted prey choices, and will therefore leave or die out when prey numbers are low. Natural enemy populations may decline or become extinct when habitats are poor or unsuitable, host pest numbers are too low, or non-selective pesticides are applied. Some species may be incapable of suppressing pests below damage thresholds by themselves. In some cases, the benefits of natural enemy presence are often undervalued because many natural enemies are difficult to sample or even detect, and there is a dearth of information on their economic value in most cropping systems. The important role of natural enemies is often not realized until disruptions such as the application of broad-spectrum insecticides precipitates target pest resurgence or secondary pest outbreaks.

Insects are susceptible to entomopathogenic nematodes (roundworms) and a variety of diseases caused by pathogenic microbes, which include viruses, bacteria, fungi, and protozoa. For example, microbial insecticides consist of a pathogen or their toxin product as the active ingredient and may provide a satisfactory alternative to chemical pesticides when used as part of an Integrated Pest Management (IPM) plan (Sarwar 2015, Azizoglu and Karabörkü 2021). The most widely used microbial pesticides are subspecies and strains of Bacillus thuringiensis (BT insecticides). Like other natural enemies, pathogens are susceptible to environmental factors, anthropogenic spread, and pest population conditions. High pest density and favorable conditions can lead to disease outbreaks that can control pests, whereas low pest densities may cause pathogens to go dormant. Microbial insecticides may be delivered through many different media including liquids used for root drenches, sprays, or solids including clay-based powders or baits interlaced with microbes. Recent advances in genetic modification technology have led to the development of new engineered microbial insecticides with increased virulence and tolerance to environmental stress, lower insect resistance, and lower spraying requirements (Azizoglu and Karabörkü 2021).

A combination of generalist and specialist natural enemies can be an extremely useful part of IPM programs that recognize and encourage their activity (Lee-Mäder et al. 2014). At the same time, one must keep in mind that, like any pest control method, biological control agents can have unanticipated effects that may include attacking beneficial and native species (Kimberling 2004, van Lenteren et al. 2006).

Types of biological control

There are three principal approaches to biological control:

1. Classical biological control
2. Augmentative biological control
3. Conservation biological control

1. Classical biological control

Classical biological control is the importation of natural enemies for release and permanent establishment in a new region. New classical biocontrol agents increasingly require long-term, stringent evaluations in quarantine to measure their non-target effects and efficacy in controlling the target pest before they may be released. Biocontrol agents that are candidates for introduction may be rejected if host range tests show that they can attack native non-target species. Another risk of introducing new biocontrol agents is that the agent may unexpectedly begin attacking non-target species (host shifting) despite previous efforts to determine its host range. Additionally, new agents may vector pathogens or hyperparasitoids, or compete with other natural enemies that exploit the same resource. Thus, evaluation of risks related to the releases of natural enemies requires integration of many aspects of their biology, as well as information on possible ecological interactions in their recipient environment (van Lenteren et al. 2006).

In the Pacific Northwest (PNW), we have had few cases of highly successful classical biocontrol of insect pests, and there have been many more successful classical weed biocontrol cases using insects (see the PNW Weed Management Handbook). One successful insect biocontrol agent, the filbert aphid parasitoid wasp, Trioxys pallidus (Braconidae), was imported from Europe and introduced (in small numbers) by Oregon State University (OSU) scientists in the mid-1980s. Since then, this tiny wasp has spread throughout the growing region and generally maintains the filbert aphid below treatment thresholds, at an estimated economic benefit of about $400,000 per year (AliNiazee 2009). In another case, the spread of and damage caused by the apple ermine moth, Yponomeuta malinellus (Yponomeutidae), has been greatly reduced by the successful introduction of a parasitoid wasp, Ageniaspis fuscicollis (Encrytidae), in the late 1990s. A cooperative biocontrol program among the US Department of Agriculture, Animal and Plant Health Inspection Service (USDA-APHIS), Oregon Department of Agriculture (ODA), and OSU for cereal leaf beetle began in 2000 and was considered successful by 2010. The establishment of the larval parasitoid wasp, Tetrastichus julis (Eulophidae), yielded control of cereal leaf beetle below thresholds in some regions of the PNW, especially when combined with altered cultural practices (tillage, irrigation, crop rotation, etc.) and pesticide applications. In some cases, 100% parasitism was achieved. A small wasp in the family Eulophidae, Colpoclypeus florus, a native of Europe, has been credited as a significant biocontrol agent of leafroller pests such as the oblique-banded and pandemis leafrollers in Washington, and has also been collected in western Oregon. An egg-larval parasitoid, Ascogaster quadridentatus (Braconidae) was introduced to help manage codling moth, Cydia pomonella (Tortricidae), a key pest of apple and pear. The presence of this parasitoid on codling moth has been reported, although the economic success of its introduction is unknown. Previous classical biocontrol efforts in the PNW have also included programs directed at Russian wheat aphid [Diuraphis noxia (Aphididae)], larch casebearer [Coleophora laricella (Coleophoridae)], and cherry bark tortrix [Enarmonia formosana (Tortricidae)].

Searches for biological control agents for two newer invasive pests in the PNW—spotted-wing drosophila [SWD, Drosophila suzukii (Drosophilidae)] and brown marmorated stink bug [BMSB, Hyalomorpha halys (Pentatomidae)]—were initiated in 2011. Several species of parasitoids, predators and entomopathogens have been evaluated for their use as biological control agents for SWD, including parasitic wasp species that were imported from Asia for quarantine, testing, and potential release (Wang et al. 2020). In 2022, Ganaspis brasiliensis (Figitidae) was approved for release across the United States, and an advantageous population of a second parasitic wasp species Leptopilina japonica (Figitdae) was discovered in Oregon. The USDA Agricultural Research Service, OSU, and ODA are releasing the tiny parasitoids across Oregon at or adjacent to berry crops impacted by SWD. The samurai wasp, Trissolcus japonicus (Scelionidae), is an egg parasitoid of BMSB that was found established outdoors in Vancouver, Washington in 2015 and in Portland, Oregon in 2016. It has also been found in at least 10 states in eastern U.S. and in B.C., Canada. It was reported to result in up to 77% parasitism of BMSB egg masses in Washington (Milnes and Beers 2019). The samurai wasp has become increasingly widespread in Oregon due to ODA’s distribution efforts and was detected in Utah and Idaho in 2019 and 2021, respectively. Orchards may benefit from samurai wasp releases in unsprayed areas adjacent to agriculture and in urban sites (Lowenstein et al. 2019). There is good documentation of traits associated with successful introductions of biocontrol agents with regard to life history traits and other attributes, and applications of these “lessons learned” may improve success rates of this strategy in the future (Kimberling 2004, Abram and Moffat 2018, Seehausen et al. 2021). Biological control of emerald ash borer [Agrilus planipennis (Buprestidae)] is being implemented as a part of an areawide management strategy to slow the spread of this invasive beetle within Oregon, where it was first detected in 2022.

2. Augmentative biological control

Augmentative or supplemental biological control typically involves the mass-production and repeated release of natural enemies to improve their population sizes, rate of colonization, and effectiveness. This approach is used most often to target slow-moving pests such as mites and aphids, usually in organic agriculture where few disruptive chemicals are applied, including home gardens and enclosed spaces such as greenhouses. The two main types of augmentative releases include 1) inundative, whereby large numbers of a natural enemy, not necessarily native or able to survive the winter, are released with the goal of single-season control (short-term biocontrol); and 2) inoculative, whereby a native or climate-adapted species is released for anticipated control after allowing populations to build up over time (long-term biocontrol). For example, both types of releases have been used to control two-spotted spider mite (Tetranychus urticae) in Oregon, which can become a secondary pest of strawberries following pesticide applications for root weevils, Otiorhynchus ovatus (Curculionidae). Mites can be controlled with an early fall inoculative release of the PNW-native predatory mite Neoseiulus fallacis (Phytoseiidae), which is available from commercial insectaries and can overwinter in the PNW (Croft and Coop 1998). Another commercially available predatory mite, N. californicus, is less tolerant of PNW winters but is still capable of providing single-season control when released by inundation (Pratt and Croft 2000).

Since natural enemies are all specialized to some degree, it’s important to correctly identify the pest and which agent(s) are appropriate for the given situation. Table 1 lists some target pests commonly found in home garden and agricultural systems, and their associated commercially-available beneficial organisms. Protocols for acquiring and releasing biocontrol agents should be carefully designed and followed to improve chances of success. Release guidelines depend on knowledge of the biology of the pest and its natural enemy, and the host plant’s influence on both species. Additionally, decisions on where and when to release the agent should consider the species’ dispersal capabilities. For example, many homeowners have wasted money using ladybug adults to control aphids only to see them fly away within minutes, particularly if agents are released during the heat of the day. Conservation efforts (below) can in some cases enhance the outcome of augmented biocontrol agents.

3. Conservation biological control

Conservation biological control refers to the manipulation and/or protection of habitat and resources to support and encourage natural enemies in order to increase their numbers and effectiveness (reviewed in Begg et al. 2017). This includes encouragement of the natural enemies’ needs such as nectar and pollen, alternative hosts, and certain types of non-disrupted habitat. Each of these resources may improve pest control because they can potentially enhance the fecundity, longevity, and survival of natural enemies.

Some practices for conservation biological control include:

• Identification skills. Learn about the beneficial insects and other organisms that frequent your crops and gardens and the biological control services they provide. A few resources to get you started include:
  • Natural enemies gallery (University of California IPM): http://ipm.ucanr.edu/natural-enemies/
  • A pocket guide to natural enemies of crop and garden pests in the Pacific Northwest (OSU; revised March 2021): https://catalog.extension.oregonstate.edu/ec1613
  • Natural enemies and beneficial insects in WA tree fruits [Washington State University (WSU)]: https://treefruit.wsu.edu/crop-protection/opm/beneficials/
  • Orchard natural enemies identification guides (WSU): http://enhancedbc.tfrec.wsu.edu/ID_guides.html
• Avoid chemicals that are toxic to your beneficial insects. Careful use of pesticides and tillage will help to avoid disrupting populations of natural enemies, which can keep secondary pests from reaching economically damaging levels. Using less toxic and more selective controls instead of broad-spectrum compounds (such as most organophosphates, carbamates, and pyrethroids) can help prevent secondary pest outbreaks. Online databases and lists of pesticide effects on beneficial organisms include:
  • http://enhancedbc.tfrec.wsu.edu/opened/
  • https://agsci.oregonstate.edu/oipmc/pesticide-risk-reduction-low-risk-pe...
  • http://ipm.ucanr.edu/PMG/r302900111.html
  • http://www.intermountainfruit.org/pesticide-tables/toxicity-pollinators
  • Provide food and shelter. Non-crop plantings in or around the crop field may provide shelter, alternative prey, nectar, and pollen for beneficial species. Table 2 provides some examples of flowering plants that are visited by natural enemies. Also consider:
• Applying food sprays. These can include yeast and sugar sprays that attract parasitoid wasps, lady beetles, lacewings, and hoverflies.
  • Manipulating crop and non-crop architecture. Consider changing your farm design in ways that can improve natural enemy activities. For example, wind-break plantings may be used as a barrier to prevent dry, dusty conditions favorable to pest mite flare-ups. Predatory mites that attack these pests may also be inhibited by such conditions. Shelter and alternate hosts can also be supported through methods such as careful rotation, alternate row harvest, and “beetle banks,” which are graded low banks or berms of dense grasses that are placed within a field or in fence row corridors inhabited by appropriate vegetation.
• Providing insectary plants. Insectary plants are grown to attract, feed, and shelter beneficial insects including pollinators and pest natural enemies. They can provide habitat, alternate prey, and floral resources (e.g., pollen, nectar, nectaries), and may include:
  • Planting within the crop field in strips or smaller blocks
  • Using perennial and annual border plantings
  • Planting within hedgerows
  • Establishing cover crops
  • Carefully managing flowering weeds

The above practices make use of beneficial species already present in the landscape, and they can enhance natural enemies released in classical and augmentative biological control programs (Colley 1998). We refer readers to several sources for additional information on practices for conservation biological control (Bugg and Waddington 1994, Long et al. 1998, Bugg 1999, Hogg et al. 2011, Parker et al. 2013, Altieri and Nicholls 2015, and Begg et al. 2017). As with selecting any new crop management method, choosing insectary plantings for conservation biological control should consider numerous biological, agronomic, and economic factors including those listed above. To justify the continued use of an insectary planting, an on-site assessment should consider the same factors as the preliminary selection process and include a sampling of pests and beneficials within and surrounding the crop.

Several studies have measured positive effects of the above practices on biocontrol performance, although efficacy will be case-specific and difficult to quantify due to the complex interactions involved (Wyckhuys et al. 2013, Begg et al. 2017). Two primary factors responsible for the disruption of conservation biological control include spatio-temporal asynchrony in pest and enemy activity and species interactions that result in weakened control of pests (Begg et al. 2017). Limitations to the implementation of effective conservation biological control can be offset to an extent by ensuring that these efforts are part of a comprehensive IPM approach.

Considerations for incorporating insectary plantings to sustain natural enemies

Timing of flowering

1. Will the floral resources be present when needed?
2. Will the flowers attract natural enemies to the target pest at certain times? Or will they draw them away from the pest?

Characteristics of the natural enemies

1. What are the relative preferences that key natural enemy and pest species have for the different flowers?
2. What are the different requirements for nectar, pollen, shelter, and alternate host food among these key species?
3. What are the foraging ranges and dispersal abilities of these key species?

Agronomic considerations

1. How competitive are the plantings with the crop or other weeds?
2. Do the plantings have the potential to harbor weeds or be weeds themselves?
3. Can the plantings serve as an alternate host for crop disease?
4. Are the plants toxic to any livestock or other local animals?

Economic and management considerations

1. Can the planting be harvested as an additional crop?
2. What are the costs of seed, establishment, and maintenance?
3. How do these costs compare to other management options?
4. Are the plantings compatible with the main pest management plan?

Resources for implementation of biological control

The IPM Practitioner’s 2015 Directory of Least Toxic Pest Control Products. A comprehensive listing of biological control agents and other “least toxic” pest control products for a variety of agricultural, urban, and domestic uses, and their producers and distributors. Bio-Integral Resource Center—https://www.birc.org/Directory.htm

“Co-managing fresh produce for nature conservation and food safety,” An informative 12-minute video on habitat and biological control made in 2015 by Eric Brennan—https://www.youtube.com/watch?v=zLvJLHERYJI

Natural Enemies Handbook: The Illustrated Guide to Biological Pest Control, by M.L. Flint, M. L, S. H. Driestadt, and J.K. Clark. 1998, 2015. University of California Division of Agriculture and Natural Resources. University of California Press, Oakland, California, USA. Publication 3386. 154 pages. Kindle and ebook editions available.

Sandhu, H. S. Wratten, R. Costanza, J. Pretty, J. R. Porter, and J. Reganold. 2015. Significance and value of non-traded ecosystem services on farmland. PeerJ 3:e762; DOI 10.7717/peerj.762—https://peerj.com/articles/762.pdf

Oregon Department of Agriculture provides a list of invertebrates approved for importation into Oregon. Except as otherwise provided in rules of the ODA, invertebrate species listed in this list may be imported, possessed, sold, purchased, exchanged or transported within the state without an ODA permit. A permit for the importation, possession, or intrastate transportation of ODA-approved species may be required by the USDA-APHIS Plant Protection and Quarantine program (Form 526)—https://www.oregon.gov/ODA/shared/Documents/Publications/IPPM/OregonAppr...

USDA SARE (Sustainable Agriculture Research and Education). SARE supports grant programs, strategies and resources that include protection of biocontrol agents and other beneficial insects—https://www.sare.org

• They produced, as the Sustainable Agricultural Network, a 128-page book, “Manage insects on your farm – a guide to ecological strategies” (Altieri and Nicholls 2005), available as a PDF download from: https://www.sare.org/publications/insect/insect.pdf
• A 116-page book, “Biological control of insects and mites,” developed largely for the midwestern US but is of interest in the PNW, is available in print and online from: https://www.northcentralsare.org/Educational-Resources/SARE-Project-Prod...
• A 108-page book, “Greenhouse IPM with an emphasis on biocontrols,” is available online from: https://www.sare.org/Learning-Center/SARE-Project-Products/Northeast-SAR...

The Xerces Society. A nonprofit organization formed in 1971 which protects wildlife through the conservation of invertebrates and their habitat. Their focus has expanded beyond native pollinators to include other invertebrate species such as native predators and parasitoids. They have programs to document the impacts of pesticides on invertebrates including biocontrol agents. Xerxes has resources to provide education and training on conservation biological control (e.g., Lee-Mäder et al. 2014) and are very active in the Pacific Northwest. 628 NE Broadway Ste 200, Portland OR 97232 USA; tel: 855-232-6639—https://www.xerces.org

References

Abram, P. K., and C. E. Moffat. 2018. Rethinking biological control programs as planned invasions. Current Opinion in Insect Science 27:9–15. https://doi.org/10.1016/j.cois.2018.01.011

AliNiazee, M.T. 2009. Biocontrol of pests a “secret” success story. News posting by Oregon State University. https://today.oregonstate.edu/archives/1997/feb/biocontrol-pests-secret-...

Altieri, M. A., and C. I. Nicholls. 2005. Manage Insects on Your Farm: A Guide to Ecological Strategies. Sustainable Agriculture Network handbook series book 7. https://www.sare.org/wp-content/uploads/Manage-Insects-on-Your-Farm.pdf

Azizoglu, U., and S. Karabörklü. 2021. Role of recombinant DNA technology to improve the efficacy of microbial insecticides. Pages 159–182 in Khan, M.A., Ahmad, W. (eds) Microbes for Sustainable Insect Pest Management. Sustainability in Plant and Crop Protection, vol 17. Springer, Cham. https://doi.org/10.1007/978-3-030-67231-7_8

Begg, G. S., S. M. Cook, R. Dye, M. Ferrante, P. Franck, C. Lavigne, G. L. Lövei, A. Mansion-Vaquie, J. K. Pell, S. Petit, N. Quesada, B. Ricci, S. D. Wratten, and A. N. E. Birch. 2017. A functional overview of conservation biological control. Crop Protection 97:145–158. http://dx.doi.org/10.1016/j.cropro.2016.11.008

Bugg, R. L., and C. Waddington. 1994. Using cover crops to manage arthropod pests of orchards: A review. Agriculture, Ecosystems Environment 50:11–28. https://doi.org/10.1016/0167-8809(94)90121-X

Bugg, R. L. 1999. Beneficial insects and their associations with trees, shrubs, cover crops, and weeds. Pages 63–65 in Bring Farm Edges Back to Life! Yolo Country Resource Conservation District, Woodland, California, USA. 105 p.

Colley, M. R. 1998. Enhancement of biological control with beneficial insectary plantings. Master’s Thesis. Oregon State University, Corvallis, Oregon, USA. https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertati...

Croft, B. A., and L. B. Coop. 1998. Heat units, release rate, prey density, and plant age effects on dispersal by Neoseiulus fallacis (Acari: Phytoseiidae) after inoculation into strawberry. Journal of Economic Entomology 91:94–100. http://jee.oxfordjournals.org/content/91/1/94

Hogg, B. N., R. L. Bugg, and K. M. Daane. 2011. Attractiveness of common insectary and harvestable floral resources to beneficial insects. Biological Control 56:76-84. https://doi.org/10.1016/j.biocontrol.2010.09.007

Kimberling, D. N. 2004. Lessons from history: predicting successes and risks of intentional introductions for arthropod biological control. Biological Invasions 6:301‒318. https://doi.org/10.1023/B:BINV.0000034599.09281.58

Lee-Mäder, E., J. Hopwood, M. Vaughan, S. H. Black, and L. Morandin. 2014. Farming with Native Beneficial Insects: Ecological Pest Control Solutions. Storey Publishing, North Adams, Massachusetts, USA.

van Lenteren, J. C., J. Bale, F. Bigler, H. M. T. Hokkanen, and A. J. M. Loomans. 2006. Assessing risks of releasing exotic biological control agents of arthropod pests. Annual Review of Entomology. 51:609–634. https://doi.org/10.1146/annurev.ento.51.110104.151129

Long, R. F., A. Corbett, L. Lamb, C. R. Horton, J. Chandler, and M. Stimmann. 1998. Beneficial insects move from flowering plants to nearby crops. California Agriculture 52:23–26. http://calag.ucanr.edu/Archive/?article=ca.v052n05p23

Lowenstein, D. M., H. Andrews, A. Mugica, and N. G. Wyman. 2019. Sensitivity of the egg parasitoid Trissolcus japonicus (Hymenoptera: Scelionidae) to field and laboratory-applied insecticide residue. Journal of Economic Entomology 112:2077–2084. https://doi.org/10.1093/jee/toz127

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Table 1. Target pests and beneficial organisms often used for augmentative biological control releases
Aphid (See also soft-bodied arthropods)	predatory midge	Aphidoletes aphidimyza
	parasitoid wasp	Aphidius ervi, A. matricariae, A. colemani, Lysiphlebus testaceipes, Trioxys pallidus
	big-eyed bug	Geocoris pallens
	lady beetle (“ladybug”)	Hippodamia convergens
	lacewing	Chrysoperla downesi, C. plorabunda, C. rufilabris
	minute pirate bug	Orius insidiosus, O. minutus, O. tristicolor
Armyworm (See also Butterfly and moth)	braconid parasitoid wasp	Chelonus insularis
Black fly larvae	bacterial endotoxin (Bti)	Bacillus thuringiensis var. israelensis (e.g., Bactimos, Teknar, Vectobac)
Butterfly and moth larvae and eggs of beetle pests in stored grain products, such as almond moth, Indian meal moth, grain weevil	parasitoid wasp	Bracon hebeter
Butterfly and moth eggs and young larvae: beet armyworm, cabbage looper, corn earworm, cutworm, diamondback moth, imported cabbageworm, codling moth and other orchard moths, tobacco budworm	viral pathogen	Nuclear polyhedrosis virus (NPV)
	bacterial endotoxin (Btk, Bta)	Bacillus thuringiensis var. kurstaki (e.g., Dipel, Javelin, Attack, Thuricide, Bactospeine, Safer’s Caterpillar Killer), Bacillus thuringiensis var. aizawai (e.g., Certan)
	parasitoid wasps of eggs	Trichogramma minutum, T. pretiosum, T. platneri
Codling moth larvae	granulosis virus pathogen	Baculovirus carpocapsae
Flea	parasitic nematode	Steinernema carpocapsae, S. feltiae
Fly (garbage- and manure-breeding)	parasitoids of puparia	Melittobia digitata, Muscidifurax raptor, Muscidifurax zaraptor, Nasonia vitripennis, Pachcrepoideus vindemiae, Spalangia cameroni, S. endius
	histerid beetle predator	Carcinops pumilio
Fungus gnat (larvae)	predatory mite	Hypoaspis miles, H. aculeifer
	parasitic nematode	Heterorhabditis megidis, Steinernema carpocapsae, S. feltiae
	bacterial endotoxin (Bti)	Bacillus thuringiensis var. israelensis
Grasshopper (nymphs and adults)	protozoan	Nosema locustae
Larvae and grubs that pupate in the soil: cucumber beetles, dampwood termites, flea beetles, root weevils, wireworms	parasitic nematodes of larvae	Heterorhabditis bacteriophora, H. heliothidis, H. megidis, Steinernema feltia, S. carpocapsae, S. riobravis
Grubs in soil such as Japanese beetle, June beetle, and white grubs	bacterial endotoxin (Btg)	Bacillus thuringiensis var. galleriae
Leafminer	braconid parasitoid of larvae	Dacnusa sibirica
Mealybug	lady beetle (“mealybug destroyer”)	Cryptolaemus montrouzieri
Mite: twospotted spider (Tetranychus urticae)	predatory mite	Amblyseius hibisci, A. mckenziei, Galendromus occidentalis, Mesoseiulus longipes, Neoseiulus californicus, N. fallacis, Phytoseiulus persimilis, P. macropilis
	predatory six-spotted thrips	Scolothrips sexmaculatus
	minute pirate bug	Orius minutus, O. tristicolor
	big-eyed bug	Geocoris pallens
Mosquito larvae	predatory fish	Gambusia affinis spp. (only in manmade water bodies or containers that have no connection to natural waterways)
	bacterial endotoxin (Bti)	Bacillus thuringiensis var. israelensis (e.g., Dunks, Bactimos, Vectobac, Teknar)
Scale: armored scale, oleander scale, San Jose scale, ivy scale	lady beetle	Chilocorus fraternus
Soft scale: citrus black scale, black/brown hemispherical, nigra scale (See also soft-bodied arthropods)	parasitoid wasp	Metaphycus helvolus
Soft-bodied arthropods: thrips, scale, aphid, spider mite, whitefly, eggs of harmful pests	lacewing larvae (in larval stage)	Chrysoperla downesi, C. plorabunda, C. rufilabris
	fungal pathogen	Beauveria bassiana
	lady beetle	Chilocorus fraternus, Hippodamia convergens
	pirate bug	Orius minutis, O. tristicolor
	predatory thrips	Scolothrips sexmaculatus
Thrips larvae (See also soft-bodied arthropods)	predatory mite	Amblyseius cucumeris, A. mckenziei, A. barkeri, A. degenerens
	lacewing	Chrysoperla downesi, C. plorabunda, C. rufilabris
	minute pirate bug	Orius minutus, O. tristicolor
Wax moth larvae (in honeycombs)	bacterial endotoxin (Bta)	Bacillus thuringiensis var. aizawai (e.g. Certan)
Weevil in landscape plants	parasitoid wasps of larvae	Anisopteromalus calandrae
	parasitic nematode	Heterorhabditis heliothidis, H. medidis, Steinernema carpocapsae, S. feltiae, S. riobravis
Whitefly nymph (see also soft-bodied arthropods)	parasitoid wasps of eggs	Encarsia formosa, Eretmocerus californicus
1 Lady beetles include many species in the family Coccinellidae, order Coleoptera. 2 Lacewings include many species in the families Chrysopidae and Hemerobiidae, order Neuroptera. 3 Parasitoid and predatory wasps include a large number of species in families such as Aphelinidae, Aphidiidae, Braconidae, Chalcididae, Crabronidae, Encyrtidae, Eulophidae, Ichneumonidae, Mymaridae, Pompilidae, Pteromalidae, Scelionidae, Specidae, and Trichogrammatidae, order Hymenoptera. 4 Hoverflies include many species in the family Syrphidae, order Diptera. 5 Predatory bugs include many species in families such as Anthocoridae, Lygaeidae, Nabidae, Pentatomidae, and Reduviidae, order Heteroptera. 6 Minute pirate bugs include many species in the family Anthocoridae, order Heteroptera. 7 Big-eyed bugs include many species in the family Lygaeidae, order Heteroptera. 8 Parasitoid Tachinid flies include many species in the family Tachinidae, order Diptera. 9 Bees include many species in families such as Anthophoridae, Apidae, Halictidae, Andrenidae, Colletidae, and Megachilidae, order Hymenoptera.

Table 2. Flowering plants visited by beneficial insects that can aid biological control conservation efforts
Common name (botanical name)	Beneficial insects
Apiaceae (Carrot family)
Angelica (Angelica)	lady beetle (“ladybugs”), lacewing
Anise (Pimpinella anisum)	parasitoid wasp
Blue lace (Trachymene caerulea)	parasitoid wasp
Caraway (Carum caryi)	hoverfly, minute pirate bug and big-eyed bug, lacewing, parasitoid wasp
Chervil (Anthriscus cerefolium)	parasitoid wasp
Coriander (Coriandrum sativum­­­­)	hoverfly, parasitoid wasp, parasitoid tachinid fly
Dill (Anethum graveolens)	hoverfly, lady beetle, parasitoid wasp
Fennel (Foeniculum vulgare)	hoverfly, parasitoid wasp, parasitoid tachinid fly
Lovage (Lovisticum officinale)	parasitoid wasp
White lace flower (Ammi majus)	hoverfly, predatory bug, lady beetle, parasitoid wasp, parasitoid tachinid fly
Wild carrot (Daucus carota)	hoverfly, predatory bug, lady beetle, lacewing, parasitoid wasp
Asteraceae (Daisy family)
Blazing star, gayfeather (Liatrus spp.)	minute pirate bug, big-eyed bug, parasitoid wasp
Chamomile (Anthemis nobilis)	lady beetle
Cosmos (Cosmos bipinnatus)	hoverfly, lacewing, minute pirate bug
Golden marguerite (Anthemis tinctoria)	lady beetle, parasitoid wasp, parasitoid tachinid fly
Goldenrod (Solidago altissima)	soldier beetle, predatory bug, lady beetle, parasitoid wasp
Marigolds, signet (Tagetes tenuifolia)	minute pirate bug, parasitoid wasp
Mexican sunflower (Tithonia tagetifolia)	hoverfly, minute pirate bug
Sunflower (Helianthus annuus and H. debilis)	hoverfly, lady beetle, parasitoid wasp
Tansy (Tanecetum)	hoverfly, lady beetle larvae, parasitoid wasp
Yarrow, milfoil (Achillea millefolium)	hoverfly, parasitoid wasp
Yarrows (A. macrophylla, A. taygetea, etc.)	hoverfly, parasitoid wasp
Brassicaceae (Cabbage family)
Broccoli (Brassica oleracea)	hoverfly, parasitoid wasp
Sweet alyssum (Lobularia maritima)	hoverfly, parasitoid wasp, parasitoid tachinid fly
Globe candytuft (Iberis umbellata)	hoverfly
Mustards (Brassica hirta and B. juncea)	hoverfly, minute pirate bug, big-eyed bug
Dipsaceae (Scabiosa family)
Cephalaria (Cephalaria giganitica)	hoverfly, parasitoid wasp
Dipsacus (Dipsacus spp.)	hoverfly
Pincushion flower (Scabiosa caucasica)	hoverfly, parasitoid wasp
Scabiosa (Scabiosa atropurpurea)	hoverfly
Fabaceae (Legume family)
Alfalfa (Medicago sativa)	bee, predatory bug, lacewing, lady beetle, parasitoid wasp
Clover (Trifolium spp.)	bee, predatory bug, lacewing, lady beetle
Vetch (Vicia spp.)	bee, predatory bug, lacewing, lady beetle
Hydrophyllaceae (Waterleaf family)
Fiddleneck/Phacelia (Phacelia tanacetifolia)	bee, predatory bug, hoverfly
Lamiaceae (Mint family)
Germander (Teucrium spp.)	bee, parasitoid wasp
Polygonaceae (Buckwheat family)
Buckwheat (Eriogonum spp. and Fagopyrum spp.)	hoverfly
See notes for Table 1.