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Entomopathogenic nematodes including Steinernema riobrave and Heterorhabditis indica were evalusted against a hive beetle Aethina tumida Murray (Coleoptera: Nitidulidae) in the field. According to Ellis et al. (2010) both nematode species caused over 76% mortality of hive beetles. Shapiro-Ilan et al. (2010) tested efficacy of H. indica and Steinernema carpocapsae against hive beetles and demonstrated that both nematode species when applied through infected host cadavers can cause up to 78% control in hive beetles. This suggests that entomopathogenic nematodes have a potential to use as biological control agents against hive beetles.

Read following papers for detail information on effect of entomopathogenic nematodes on small hive beetles.

Ellis, J.D., Spiewok, S., Delaplane, K.S., Buchholz, S., Neumann, P. and Tedders, W.L. 2010.  Susceptibility of Aethina tumida (Coleoptera: Nitidulidae) larvae and pupae to entomopathogenic nematodes. Journal of Economic Entomology. 103: 1-9.

Shapiro-Ilan, D.I., Morales-Ramos, J.A., Rojas, M.G. and Tedders, W.L. 2010.  Effects of a novel entomopathogenic nematode-infected host formulation on cadaver integrity, nematode yield, and suppression of Diaprepes abbreviatus and Aethina tumida. Journal of Invertebrate Pathology. 103: 103-108.

How to apply nematodes

Insect-parasitic nematodes can be easily applied using conventional pesticide and fertilizer sprayers that have up to 300 PSI pressures.  However, nematodes will be easily damaged, if they are agitated through excessive recirculation of spray mix or if the temperature in the tank increases beyond 86 degrees F. Nematodes can also be applied through different types of irrigation systems but pumps should have proper pressure to avoid damage to nematodes and screen sizes should be larger than 50 mesh so that nematodes will pass through them live. Watering cans are used to apply nematodes in small areas including vegetable and ornamental gardens.

How many nematodes should be applied

For the suscessful control most of the soil dweling insect pests, the optimal rate of 1 billion infective juvenile nematodes in 100 to 260 gallons of water per acre is generally recommended.

Optimal soil and environmental condtions to apply nematodes

All nematodes require proper soil moisture for their optimal movement and infectivity. The activity and infectivity of nematodes can be enhanced by maintaining optimum moisture levels in the soil before and after their application.  In case of nematode application in turf, turf should be irrigated immediately after applicationwith at least 1/2 inch of water to rinse off nematodes from the folliage and move them into the soil and thatch. As nematodes are very sensitiv to heat and cold, their infectivity will be reduced if soil temperature is below 4 degrees C and above 35 degrees C. Soil temperatures between 20 to 30 degrees C are considered favourable for application of majority of nematode species and their virulence.  Nematode survival and activity also influenced by soil type.  Both survival and activity of nematodes is higher in sandy-loam soils than in heavy clay soils.

When to apply nematodes

Since nematodes are very sensitive to UV light, they will die within a minute or two when exposed to full sun. Therefore, nematodes should be applied early in the morning or late in the evening to avoid exposure to UV light.

Pulse (legume) grains are considered as the important sources of protein, fats, carbohydrates, sugar and vitamin. B.  In developing countries pulses are a cheaper protein source than meat.  Many insect pests including red flour beetle Tribolium castaneum (Herbst), India meal moth Plodia interpunctella, Mediterranean flour moth Ephestia kuehniella (Zeller), saw thoothed grain beetle Oryzaephilus surinomensis (L.), yellow mealworm Tenebrio molitor (L.) and the ware house beetle Trogoderma variable (Ballion) cause a serious damage to these crops in the field and grains in the storage.  The efficacy of entomopathogenic nematodes against many stored grain/product pests have been studied by many researchers (Athanassiou et al., 2008; Moris, 1985; Romos-Rodriguez et al., 2006).  In the laboratory, an entomopathogenic nematode, Steinernema feltiae when applied at the rate 900 infective juveniles per insect caused over 66% mortality of both adults and larvae of T. confusum. This nematode when applied at the same rate also caused over 52% mortality of E. kuehniella. (Athanassiou et al., 2008)  Under laboratory conditions, another species of nematode, S. riobrave can cause about 70% mortality of T. castaneum (Ramos-Rodríguez et al., 2007). It has also been demonstrated that nematodes including S. carpocapsae, Heterorhabditis bacteriophora and H. megidis have a potential to control the adults of two stored grain pests including, Sitophilus granarius and O. surinamensis (Tradan, 2006). Mbata and Shapiro-IIan (2005) also showed that various heterorhabditis nematodes including H. bacteriophora (HP88, Lewiston, and Oswego strains); H. indica (Homl strain); H. marelatus (Point Reyes strain); H. megidis (UK211 strain); and H. zealandica (NZH3 strain) have potential to kill larvae and adults of P. interpunctella.

For more information on biological control of stored grain pets with entomopathogenice nematodes; please read following research papers:

Athanassiou CG, Palyvos NE, Kakoull-Duarte T. 2008. Insecticidal effect of Steinernema feltiae (Filipjev) (Nematoda : Steinernematidae) against Tribolium confusum du Val (Coleoptera : Tenebrionidae) and Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) in stored wheat  Journal of Stored Products Research. 44: 52-57.

Mbata, G.N., and Shapiro-Ilan, D.I. 2005. Laboratory evaluation of virulence of heterorhabditid nematodes to Plodia interpunctella Hübner (Lepidoptera: Pyralidae). Environmental Entomology 34: 676 – 682.

Ramos-Rodríguez, O., Campbell, J. F., and Ramaswamy, S. 2006. Pathogenicity of three species of entomopathogenic nematodes to some major stored- product insect pest. Journal of Stored Product Research 42: 241 – 252.

Ramos-Rodríguez,O.,Campbell, J. F.,and Ramaswamy, S. 2007. Efficacy of the   entomopathogenic nematodes Steinernema riborave against the stored-product pests Tribolium castaneum and Plodia interpunctella. Biological Control 40:15 -21.

Tradan, S., Vidric, M., and Valic, N. 2006. Activity of four entomopathogenic nematodes against young adult of Sitophilus granarious (Coleptera: Curculionidae ) and Oryzophilus surinamensis ( Coleoptera: Silvanidae ) under laboratory condition. Plant Disease and Protection. 113: 168 – 173.

• Several fungus gnat species including Bradysia coprophila, B. impatiens and B. difformis are considered economically important indoor and greenhouse pests in Europe and the US. Fungus gnat flies are black or gray in color with clear wings, relatively small (3-4 mm) in size and commonly associated with compost and natural soils with high organic contents. You can see these hopping flies when you water your plants. Fungus gnat maggots (larvae) are white-bodied with black heads and can be found just under the surface of the potting medium/soil. These maggots primarily feed on fungi and organic matter but they can also cause a serious damage to many ornamental plants. Maggots often chew or strip plant roots and tunnel stems affecting water and nutrient absorption in severely injured plants resulting in lost vigor, turn off-color and eventually death. Maggots are also capable of transmitting fungal pathogens (Fusarium, Phoma, Pythium and Verticillium) during feeding. Adult flies are nuisance to people and disseminate fungal spores from plant to plant as they disperse through the greenhouse. Females often laying over 1000 eggs in a lifetime on the media surface and completing egg-to-egg life cycle within 20-25 days at 20-25oC. Continuous and overlapping generations of fungus gnats in the greenhouse have made most control strategies difficult.
• Currently, most growers rely on insecticides to manage fungus gnats in floriculture. However, use of these insecticides is restricted due to their environmental pollution and human health concerns, development of resistance to pesticides and removal of some of the most effective products from the market. Biological control agents including Bacillus thuringiensis (Bt), the predatory mite, Hypoaspis miles and entomopathogenic nematodes have been used as alternatives to chemical pesticides.
• The entomopathogenic nematodes species including Heterorhabditis bacteriophora GPS11 strain, H. indica LN2 strain and Steinernema feltiae UK strain have a potential to use as biocontrol agents against fungus gnats. These nematodes kill both maggots (larvae) and pupae, but the second and fourth stages are most susceptible than pupae. Nematodes are generally applied in water suspension as spray applications to the surface of plant growing medium to target larval and pupal stages. The potting medium (Ball-mix, Nursery-mix or Pro-mix) can influence the survival, persistence and efficacy of entomopathogenic nematodes in greenhouse production. In the Nursery-mix, H. bacteriophora can survive longer and perform better than H. indica, H. marelatus Oregon, H. zealandica X1 and Steinernema feltiae against fungus gnats. In the Pro-mix, only H. indica have performed better than all other nematode species that tested against fungus gnats. Application of S. feltiae can cause 40% reduction in fungus gnat population in Ball-mix, 50% in Metro-mix and 56% in Pro-mix, but only 27% in the Nursery-mix. In the greenhouse, temperature can influence efficacy of nematodes. For example, H. bacteriophora and H. indica can survive and cause very high mortality of fungus gnats at warmer (above 25oC) temperatures whereas S. feltiae is generally effective against fungus gnats at cooler (below 25oC) temperatures. Application of an appropriate concentration of nematodes is a crucial step in the cost effective control of fungus gnats in greenhouse production. Generally, application of one billion infective juveniles of H. bacteriophora, H. indica or S. feltiae per acre can kill over 50% fungus gnats in greenhouse productions.

How entomopathogenic nematodes kill fungus gnats

• When the infective juveniles are applied to the surface of plant growing medium, they start searching for hosts, in this case fungus gnat maggots (larvae) and pupae.
• Once a maggot/pupa has been located, the nematode infective juveniles penetrate into the maggot body cavity via natural openings such as mouth, anus and breathing pores called spiracles.
• Infective juveniles of Heterorhabditis spp also enter through the intersegmental members of the maggot/pupal cuticle.
• Once in the body cavity, infective juveniles release symbiotic bacteria (Xenorhabdus spp. for Steinernematidae and Photorhabdus spp. for Heterorhabditidae) from their gut in the fungus gnat blood.
• Multiplying nematode-bacterium complex causes septicemia and kills the host usually within 48 h after infection.
• Nematodes feed on multiplying bacteria, mature into adults, reproduce and then emerge as infective juveniles from the cadaver to seek new maggots in the potting medium/soil.

Nematodes are now commercially available from many suppliers distributed throughout in the USA.

For more information on biological control of fungus gnats, please read following research papers/book chapters:

• Binns, E.S., 1973.  Fungus gnats (Diptera: Mycetophilidae, Sciaridae) and the role of mycophagy in soil: a review. Rev. Ecol. Biol. Sol. 18, 77-90.
• Chambers, R.J., Wright, E.M., Lind, R.J., 1993.  Biological control of glasshouse sciarid larvae (Bradysia spp.) with the predatory mite, Hypoaspis miles on Cyclamen and Poinsettia. Biocontrol Sci. Technol. 3, 285-293.
• Ecke, P.Jr., Faust, J.E., Williams, J., Higgins, A., 2004.  The Poinsettia Manual. Ball Publishing, The Paul Ecke Ranch, Encinitas, California, USA.
• Freeman, P., 1983.  Sciarid flies, Diptera; Sciaridae. Handbooks for the identification of British insects 9, Part 6. London, Royal Entomol. Soc. pp 68.
• Gillespie, D.R., Menzies, J.G., 1993.  Fungus gnat vector Fusarium oxysporum f. sp. radicislycopersici.  Ann. Appl. Biol. 123, 539-544.
• Gouge, D.H., Hague, N.G.M., 1994.  Control of sciarids in glass and propagation houses with Steinernema feltiae. Brighton Crop Protection Conference: Pest Dis. 3, 1073-1078.
• Gouge, D.H., Hague, N.G.M., 1995.  Glasshouse control of fungus gnats, Bradysia paupera, on fuchsias by Steinernema feltiae. Fundam. Appl. Nematol. 18, 77-80.
• Grewal, P.S., Richardson, P.N., 1993.  Effects of application rates of Steinernema feltiae (Nematoda: Steinernematidae) on control of the mushroom sciarid fly, Lycoriella auripila (Diptera: Sciaridae).  Biocontrol Sci. Technol. 3, 29-40.
• Grewal, P.S., Tomalak, M., Keil, C.B.O., Gaugler, R., 1993. Evaluation of a genetically selected strain of Steinernema feltiae against the mushroom sciarid fly, Lycoriella mali. Ann. Appl. Biol. 123, 695-702.
• Harris, M.A., Oetting, R.D., Gardner, W.A., 1995.  Use of entomopathogenic nematodes and new monitoring technique for control of fungus gnats, Bradysia coprophila (Diptera: Sciaridae), in floriculture. Biol. Control 5, 412-418.
• Jagdale, G. B., Casey, M. L., Grewal, P. S. and Lindquist, R. K. 2004.  Application rate and timing, potting medium and host plant on the efficacy of Steinernema feltiae against the fungus gnat, Bradysia coprophila, in floriculture. Biol. Contrl. 29: 296-305.
• Jagdale, G. B., Casey, M. L., Grewal, P. S. and Luis Cañas. 2007.  Effect of entomopathogenic nematode species, split application and potting medium on the control of the fungus gnat, Bradysia difformis (Diptera: Sciaridae), in the greenhouse at alternating cold and warm temperatures. Biol. Control. 43: 23-30.
• Kim, H.H., Choo, H.Y., Kaya, H.K., Lee, D.W., Lee, S.M., Jeon, H.Y., 2004.  Steinernema carpocapsae (Rhabditida: Steinernematidae) as a biological control agent against the fungus gnat Bradysia agrestis (Diptera: Sciaridae) in propogation houses. Biocontrol Sci. Technol. 14, 171-183.
• Lindquist R., Piatkowski J. 1993. Evaluation of entomopathogenic nematodes for control of fungus gnat larvae. Bull. Int. Organiz. Biol. Integr. Control Noxious Animals and Plants. 16, 97-100.
• Lindquist, R.K., Faber, W.R., Casey, M.L., 1985.  Effect of various soilless root media and insecticides on fungus gnats.  HortScience. 20, 358-360.
• Menzel, F., Smith, J.E., Colauto, N.B., 2003.  Bradysia difformis Frey and Bradysia ocellaris (Comstock): two additional neotropical species of black fungus gnats (Diptera : Sciaridae) of economic importance: a redescription and review. Ann. Entomol. Soc. Am. 96, 448-457.
• Nielsen, G. R., 2003. Fungus gnats. http://www.uvm.edu/extension/publications/el/el50.htm
• Oetting, R.D., Latimer, J.G., 1991.  An entomogenous nematode Steinernema carpocapsae is compatible with potting media environments created by horticultural practices. J. Entomol. Sci. 26, 390-394.
• Olson, D.L., Oetting, R.D., van Iersel, M.W., 2002.  Effect of soilless media and water management on development of fungus gnats (Diptera: Sciaridae) and plant growth. HortScience. 37: 919-923.
• Richardson, P.N., Grewal, P.S., 1991.  Comparative assessment of biological (Nematoda: Steinernema feltiae) and chemical methods of control of mushroom fly, Lycoriella auripila (Diptera: Sciaridae).  Biocontrol Sci. Technol. 1, 217-228.
• Tomalak, M., Piggott, S. and Jagdale, G. B. 2005.  Glasshouse applications. In: Nematodes As Biocontrol Agents. Grewal, P.S. Ehlers, R.-U., Shapiro-Ilan, D. (eds.). CAB publishing, CAB International, Oxon. Pp 147-166.
• Wilkinson, J.D., Daugherty, D.M., 1970.  Comparative development of Bradysia impatiens (Diptera: Sciaridae) under constant and variable temperatures. Ann. Entomol. Soc. Am. 63, 1079-1083.

The oriental beetle, Anomala orientalis is one of most damaging white grub species of turfgrass. An entomopathogenic nematode, Steinernema scarabaei has been used as effective biological control agent against these beetles.  When infective juveniles of this nematode applied at the rate of 2.5 billion per hectare of turfgrass they can suppress over 77% population of oriental beetles (Koppenhofer and Fuzy, 2009).

For more information on the effects of entomopathogenic nematodes on different species of white grubs.

Alm, S.R., Yeh, T., Hanula, J.L. and Georgis, R. 1992. Biological control of japanese, oriental and black turfgrass ataenius beetel (Coleoptera, Scarabidae) larvae with entomopathogenic nematodes (Nematoda, Steinernematidae, Heterorhabditidae). Journal of Economic Entomology. 85: 1660-1665.

Choo, H.Y., Kaya, H.K., Huh, J., Lee, D.W., Kim, H.H., Lee, S.M. and Choo, Y.M. 2002. Entomopathogenic nematodes (Steinernema spp. and Heterorhabditis bacteriophora) and a fungus Beauveria brongniartii for biological control of the white grubs, Ectinohoplia rufipes and Exomala orientalis, in Korean golf courses. Biocontrol. 47: 177-192.

Koppenhofer, A.M., Brown, I.M., Gaugler, R., Grewal, P.S., Kaya, H.K. and Klein MG. 2000. Synergism of entomopathogenic nematodes and imidacloprid against white grubs: Greenhouse and field evaluation. Biological Control. 19: 245-251.

Koppenhofer, A.M. and Fuzy, E.M. 2009. Long-term effects and persistence of Steinernema scarabaei applied for suppression of Anomala orientalis (Coleoptera: Scarabaeidae). Biological Control. 48: 63-72.

Koppenhofer, A.M. and Fuzy E.M. 2004. Effect of white grub developmental stage on susceptibility to entomopathogenic nematodes. Journal of Economic Entomology. 97: 1842-1849.

Koppenhofer, A.M. and Fuzy, E.M. 2003. Steinernema scarabaei for the control of white grubs. Biological Control. 28: 47-59.

Koppenhofer, A.M. and Fuzy, E.M. 2008. Effect of the anthranilic diamide insecticide, chlorantraniliprole, on Heterorhabditis bacteriophora (Rhabditida : Heterorhabditidae) efficacy against white grubs (Coleoptera : Scarabaeldae). Biological Control. 45: 93-102.

Koppenhofer, A.M., Fuzy, E.M., Crocker, R.L., Gelernter, W.D. and Polavarapu, S. 2004. Pathogenicity of Heterorhabditis bacteriophora, Steinernema glaseri, and S. scarabaei (Rhabditida : Heterorhabditidae, Steinernematidae) against 12 white grub species (Coleoptera : Scarabaeidae). Biocontrol Science and Technology. 14: 87-92.

Koppenhofer, A.M., Cowles, R.S., Cowles, E.A., Fuzy, E.M. and Baumgartner, L. 2002. Comparison of neonicotinoid insecticides as synergists for entomopathogenic nematodes. Biological Control 24: 90-97.

Koppenhofer, A.M., Grewal, P.S. and Fuzy, E.M. 2006. Virulence of the entomopathogenic nematodes Heterorhabditis bacteriophora, Heterorhabditis zealandica, and Steinernema scarabaei against five white grub species (Coleoptera : Scarabaeidae) of economic importance in turfgrass in North America. Biological Control 38: 397-404

Lee, D.W., Choo, H.Y., Kaya, H.K., Lee, S.M., Smitley, D.R., Shin, H.K. and Park, C.G. 2002. Laboratory and field evaluation of Korean entomopathogenic nematode isolates against the oriental beetle Exomala orientalis (Coleoptera : Scarabaeidae). Journal of Economic Entomology. 95: 918-926.

Li, X.Y., Cowles, R.S., Cowles, E.A., Gaugler, R. and Cox-Foster, D.L. 2007. Relationship between the successful infection by entomopathogenic nematodes and the host immune response. International Journal for Parasitology. 37: 365-374.

Mannion, C.M., McLane, W., Klein, M.G., Moyseenko, J., Oliver, J.B. and Cowan D. 2001. Management of early-instar Japanese beetle (Coleoptera : Scarabaeidae) in field-grown nursery crops. Journal of Economic Entomology. 94: 1151-1161.

Polavarapu, S., Koppenhoefer, A.M., Barry, J.D., Holdcraft, R.J. and Fuzy, E.M. 2007. Entomopathogenic nematodes and neonicotinoids for remedial control of oriental beetle, Anomala orientalis (Coleoptera : Scarabaeidae), in highbush blueberry. Crop Protection. 26: 1266-1271.

Yeh, T. and Alm, S.R. 1995. Evaluation of Steinernema glaseri (Nematoda: Steinernematidae) for biological control of japanese and apanese and oriental beetles (Coleoptera, Searabaeidae). Journal of Economic Entomology. 88: 1251-1255.

Yi, Y.K., Park, H.W., Shrestha, S., Seo, J., Kim, Y.O., Shin, C.S. and Kim, Y. 2007. Identification of two entomopathogenic bacteria from a nematode pathogenic to the oriental beetle, Blitopertha orientalis. Journal of Microbiology and Biotechnology. 17: 968-978.

It has been reported that three entomopathogenic nematode species including Steinernema carpocapsae Mexican 33 strain, S. feltiae UK76 strain and Heterorhabditis bacteriophora HP88 strain can infect and kill desert subterranean termite s Heterotermes aureus under laboratory conditions (Yu et al., 2008). These nematodes can also develop and reproduce in termite cadavers and emerge as infective juveniles.

Please read following literature for more information on interaction between insect-parasitic nematodes and termites.

Yu, H., Gouge, D.H., Stock, S.P. and Baker, P.B. 2008. Development of entomopathogenic nematodes (Rhabditida: Steinernematidae; Heterorhabditidae) in desert subterranean termite Heterotermes aureus (Isoptera: Rhinotermitidae). Journal of Nematology. 40: 311-317.

Before starting to write about this topic, I would like to make it clear that taxonomically all bugs are insects but all the insects are not bugs. As far as I know, both in the USA and Canada, almost all people except entomologists call each and every insect as a bug.  Even extension entomologists when they are giving extension seminars to farmers/growers about insect pests of different crops, they often refer them as bad bugs for the understanding of growers. “True” bugs are mainly belong to two insect orders including Hemiptera and Homoptera.

All natural enemies of insect pests are considered as good bugs because they can kill and feed on insect pests that cause tremendous yield losses to many economically important crops. Since many of these natural enemies are commercially produced and used in the integrated pest management program (IPM), they are called as biological control agents. These biological control agents can be parasitic or predatory insects.  In addition to these predators and parasites (good bugs), there are some microorganisms such as bacteria, fungi, protozoa and viruses that can cause diseases and kill insect pests.  These microorganisms are termed as insect pathogens and also considered as biological control agents. Nematodes belonging to two families, Steinernematidae and Heterorhabditidae are also considered as insect parasites or pathogens and used as biological agents in controlling many soil dwelling insect pests of many economically important crops (in this blog, please read several posts that are devoted to insect- parasitic nematodes). Furthermore, mites are closely related to spiders but not considered as insects. Some species of mites are predatory in nature but others are serious pests of many plant species.

Predators: Although, there are many kinds of vertebrate predators including birds, amphibians, reptiles, fish and mammals that feed on insects, in this blog I am going to focus on the predatory insects that are generally used in biological control programs. These insects are called predators because they feed and complete their entire life cycle by remaining outside of their prey host as opposed to parasites that complete at least part of their life cycle inside their hosts.  Predators are generally larger than their prey, they kill and feed on both immature and adult stages of many different kinds of hosts.

Following are the examples of insect predators that can be used as biological control agents against many kinds of insect pests.

Aphid midge (Aphidoletes aphidimyza): This predatory midge fly often found in many vegetable crops (potatoes, cabbage and cauliflower), fruit orchards (apple, blueberries and peaches) and many ornamental plants throughout North America. The larval stages of this midge fly are mainly predators of aphids. This midge fly is commercially available and widely used as biocontrol agents in the greenhouses against over 60 species of aphids infesting both vegetable and ornamental plants.

Bigeyed bug (Geocoris spp.): There are four most common species of bigeyed bug (G. punctipes, G. pallens, G. bullatus and G. uliginosus) found in almost all cropping systems in North America.  Bigeyed bugs generally feed on many small insects including aphids, mites and whiteflies, eggs and nymphs of many plant bugs. They can also feed on eggs and small larval stages of cotton ballworms, pink ballworms and tobacco budworms. Since this bug is very susceptible to broad spectrum pesticides, care should be taken to avoid killing of this important biocontrol agent.  This predator is commercially available from insectories in the USA.

Brown lacewings (Hemerobius stigma): These lacewings found throughout North American forests and are mainly predators of aphids and many other soft-bodied small insects including balsam woolly adelgis (Adelges piceae), pine bark adelgid (Pineus strobi) and Cooley’s spruce gall adelgid (Adelges cooleyi). These lacewings are not commercially available.

Deraeocoris bug (Deraeocoris nebulosus): This is a very important predator of many insect and mite pests different agricultural, horticultural and landscape plants in the Canada and USA. This is a true predatory bug, which is generally found in many fruit orchards including apple, peach and pecan.  They also found in cotton fields and many landscape settings.  These bugs are natural enemies of many small insects including aphids, lace bugs, psyllids, scales and whiteflies. They also feed on mites. These bugs are not commercially available.

Dragon and damselflies: Adult dragon and damsel flies generally feed on small flying small adult insects including midge flies, mayflies, mosquitoes, ants and termites in the air where as dragon/damsel fly nymphs feed on mosquito larvae in the water.

Green lacewing (Chrysoperla carnea, C. rufilabris): Lacewings adults are not predatory in nature but mainly feed on nectar, honeydew and pollens.  However, larvae of lacewings are predatory in nature and feed on insect pests of many crops including apples, asparagus, cotton, corn, cole crops, eggplants, leafy vegetables, potatoes, tomatoes, peppers and strawberries. Lacewing larvae generally prey on aphids, leafhopper eggs, eggs of butterflies and moths, mealybugs, mites, thrips, small larvae of beetles and moths. Both species of lacewings are commercially available and sold in all stages (eggs, larvae and adults).

Ladybird beetles (Hippodamia parenthesis and Harmonia axyridis): These beetles are also recognized as lady beetles or ladybugs and more than 450 of this beetles have been reported from North America. Both larval and adult stages of this predator found on many agricultural and ornamental plants and they primarily feed on aphids. In addition, they can feed on small insects, mites, scales, thrips and eggs of many moths and beetles. they can eat nectar or pollen if insect hosts are not around. These predators are now commercially available to use against many crop pests, especially aphids.

Lebia beetles (Lebia grandis): These beetles are natural enemies of Colorado potato beetle, Leptinotarsa decemlineata. Adults of the predatory insect can feed on all immature stages of colorado potato beetle. Larval stages of Labia beetles are generally parasitic in nature and therefore, they are considered as ectoparasites of larval and pupal stages of colorado potato beetles. These predators are not commercially produced.

Pirate bugs (Orius spp.): Both adults and nymphs of these predatory insects have a sharp, needle-like beak that they use to suck body content of their prey. These insects found in many crops including alfalfa, corn, cotton, pea, peanuts, and strawberries. These are predators of aphids, mites, thrips, small larval stages of many insects, eggs of many different kinds of insects. These insect predators are commercially available in the USA and most often suscessfully used as biocontrol agents in controlling greenhouse pests.

Rove beetles (Aleochara bilineata): These beetles naturally found in many vegetable crops including onions, different cole crops, turnip, radish and sweet corn.  Rove beetle adults are predatory in nature but their larval stages are parasitic in nature. Rove beetles generally feed on egg, larval and pupal stages of onion and cabbage maggots. These insects are not commercially available.

Soldier beetles (Chauliognathus marginatus and C. pennsylvanicus): These beetles are also called leatherwing beetle because of texture of their wings. Larvae of this insect mainly feed on grasshopper eggs, both adult and nymphal stages of aphids, soft bodied larvae of many insects (cutworms, gypsy moths) whereas adults mainly feed on adult aphids and other soft bodied insects. These predators also feed on snails and slugs. These insects are not pest any plant species but they can eat nector or pollen if insect hosts are not around.

Spined soldier bug (Podisus maculiventris): This is a “true bug” that also named as a stink bug because it emits a strong stinky odour when disturbed. Like Pirate bugs, this bug also uses its sharp beak to suck the body content of its prey. This predator feeds on immature stages of many insect pests including beet armyworm, cabbage loopers, cabbageworm, colorado potato beetle, corn earworm, diamond backmoth, Eropean corn borer, fall armyworms, flea beetles, Mexican bean beetle and velvetbean caterpillars. These insect predators are commercially available.

What is biological control of insect pests? Biological control is a method in which natural enemies are introduced in the fields or greenhouses to suppress the populations of economically important insect pests of many plant species.

Natural enemies may include predators, parasities and pathogens.

Predators: Predators are the group of vertebrate animals and invertebrates that generally kill and feed externally on their host and also complete their entire life cycle outside the host body as opposed to parasites. Vertebrate predators of insect include birds, amphibians, reptiles, fish, mammals and invertebrate predators include dragon flies, damselflies, soldier beetles, ladybird beetles, ground beetles, rove beetles, lacewings and hover flies. Several species of mites and Spiders are predators of many species of pest insects and mites. Insect predators are generally used in biological control programs against many small insects like midgeflies, gnats, mosquitoes and larvae of many soft bodied insects.

Parasites (Parasitoids) : Larvae of parasitic insects also called parasitods sometime during their life cycle generally enter the body of insect host where they feed, develop, eventually kills their host and emerge in the environment as adult. These adults are typically free-living but they can feed on other insects as predators and on honeydew, plant nectar or pollen when their prey is not around. Since parasites complete part of their life cycle inside their hosts, they have to adapt with the life cycle, physiology and defense mechanisms of their hosts. Many kinds of parasitoids have been included biological control programs and successfully used against many insect pests especially in European greenhouses. For example, parasitic wasp, Pediobius foveolatus is commercially available and widely used against Mexican bean beetles in the fields.

Pathogens: Pathogens are group of microorganisms including bacteria, fungi, protozoans and viruses can infect and cause diseases in insects.  These diseases caused by pathogens may inhibit the rate of feeding, reproduction, development of insect pests or kill their populations entirely.  One of the most popular insect pathogen is a bacterium, Bacillus thuringiensis (Bt), which has been widely used against many economically insect pests of both field and greenhouse crops.

Beneficial nematodes: Beneficial nematodes include Steinernema spp. and Heterorhabditis spp. These nematodes are considered as parasites or pathogens of insects. These nematodes are commercially available and have been used as biological agents in controlling many soil dwelling insect pests of many economically important crops. You can find more information on these nematodes somewhere ealse in this blog.

The western corn rootworm (Diabrotica virgifera virgifera) is a very serious pest of corn in the North America and Europe. Larvae of this insect exclusively feed on maize roots, often causing plant lodging whereas adults may reduce yields through silk feeding and interfering maize pollination.  Insect-parasitic Heterorhabditid and Steinernematid nematodes have been applied for the control of D. v. virgifera larvae in the fields.  Heterorhabditis bacteriophora is proved to be as effective as pyrethroid insecticide, tefluthrin in reducing over 65% emergence adults of rootworms.  Application of tefluthrin in combination with Steienernema carpocapsae can result in a synergistic response that can lead to increased mortality of rootworms by 24%.  Also, entomopathogenic nematodes including Steinernema glaseri, Steinernema arenarium, Steinernema abassi and Heterorhabdtis bacteriophora when applied at the rate of 8-16 nematodes per cm² under laboratory condtions caused over 77% larval mortality.

For more information on corn rootworms and entomopathogenic nematode interactions, read following literature

Jackson, J.J. 1995.  Pathogenicity of entomopathogenic nematodes for third instars of the western corn rootworm. J Nematol 27:504.

Jackson, J.J. 1996.  Field performance of entomopathogenic nematodes for suppression of western corn rootworm (Coleoptera: Chrysomelidae). J Econ Entomol 89:366–372.

Jackson, J.J. 1997.  Field efficacy and ecology of three entomopathogenic nematodes with the western corn rootworm. J Nematol 29:586.

Jackson, J.J., Brooks, M.A. 1995.  Parasitism of western corn rootworm larvae and pupae by Steinernema carpocapsae. J Nematol 27:15–20.

Journey, A.M., Ostlie, K.R. 2000.  Biological control of the western corn rootworm (Coleoptera: Chrysomelidae) using the entomopathogenic nematode, Steinernema carpocapsae. Environ Entomol 29:822–831.

Kurtz, B., Toepfer, S., Ehlers, R.U., Kuhlmann, U. 2007.  Establishment and persistence of Heterorhabditis bacteriophora, H. megidis, and Steinernema feltiae for controlling Diabrotica virgifera virgifera larvae in maize. J Appl Entomol 131:420–425.

Pilz, C. 2008.  Biological control of the invasive maize pest Diabrotica virgifera virgifera by the entomopathogenic fungus Metarhizium anisopliae. PhD thesis at the University of Natural Resources and Applied Life Sciences BOKU, Vienna, 155 pp.

Pilz, C., Wegensteiner, R., Keller, S. 2007.  Selection of entomopathogenic fungi for the control of the western corn rootworm Diabrotica virgifera virgifera. J Appl Entomol 131:426–431.

Pilz, C., Keller, S., Kuhlmann, U. and Toepfer, S. 2009. Comparative efficacy assessment of fungi, nematodes and insecticides to control western corn rootworm larvae in maize. Biocontrol 54: 671-684.

Pilz, C., Wegensteiner, R., Keller, S. 2008.  Natural occurrence of insect pathogenic fungi and insect parasitic nematodes in Diabrotica virgifera virgifera populations. BioControl 53:353–359.

Poinar, G.O. Jr., Evans, J.S., Schuster, E. 1983.  Field test of the entomogenous nematode, Neoaplectana carpocapsae, for control of corn rootworm larvae (Diabrotica sp., Coleoptera). Prot Ecol 5:337–342.

Toepfer S, Peters A, Ehlers, R.U., Kuhlmann, U. 2008.  Comparative assessment of the efficacy of entomopathogenic nematode species at reducing western corn rootworm larvae and root damage in maize. J Appl Entomol 132:337–348.

Toepfer, S., Gueldenzoph, C. Ehlers, R.U. and Kuhlmann, U. 2005. Screening of entomopathogenic nematodes for virulence against the invasive western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) in Europe. Bulletin of Entomological Research. 95: 473- 482.

Insect Species: Entomopathogenic nematode species

Ø Apopka weevil (Diaprepes abbreviatus): S. carpocapsae All strain

Ø Armyworm (Heliothis armigera): S. carpocapsae All strain

Ø Billbugs (Sphenophorus purvulus): H. bacteriophora & S. carpocapsae All strain

Ø Black vine weevil (Otiorhynchus salcatus): S. carpocapsae All & UK strains, S. feltiae, S. glaseri & H. megidis UK 211 strain

Ø Blue grass weevil (Listronotus maculicollis): H. bacteriophora & S. carpocapsae

Ø Carpenter worms (Cossus cossus): S. carpocapsae

Ø Carrot weevil (Listronotus oregonensis): S. feltiae

Ø Cat fleas (Ctenocephalides felis): S. carpocapsae

Ø Citrus root weevil (Pachnaeus litus): S. carpocapsae All strain

Ø Clover root weevil (Sitona hispidulus): S. feltiae & H. bacteriophora

Ø Codling moth (Cydia pomonella): S. carpocapsae

Ø Crane flies (Tipula spp.): S. carpocapsae & H. megidis

Ø Cutworms (Agrotis ipsilon, A. segetum): S. carpocapsae All strain

Ø Dog fleas (Ctenocephalides cannis): S. carpocapsae

Ø Face fly (Musca autumnalis): S. carpocapsae, H. bacteriophora & S. feltiae

Ø Fall web worms (Hyphantria cunea): S. carpocapsae

Ø Flea beetles (Phyllotreta spp.): S. carpocapsae

Ø Fungus gnats (Bradysis spp.): H. bacteriophora, H. indica, H. zealandica, S. anomali, S. carpocapsae, S. feltiae SN strain & S. riobrave

Ø House flies (Musca domestica): S. carpocapsae, H. bacteriophora & S. feltiae

Ø Hunting billbug (Sphenophorus venatus venatus): S. carpocapsae All strain

Ø Japanese beetle (Popillia japonica): H. bacteriophora, H. indica, H. marelata, H. megidis, H. zealandica, S. anomali, S. carpocapsae, S. feltiae, S. glaseri, S. kushidai, S. riobrave, S. scapterisci & S. scarabae

Ø Leaf minors (Liriomyza trifolii): S. carpocapsae & S. feltiae

Ø Leopard moth (Zeuzera pyrina): S. carpocapsae

Ø Mole crickets (Gryllotapla gryllotapla): S. riobravis & S. scapterisci

Ø Peach borer moth (Synanthedon exitiosa): S. carpocapsae

Ø Pecan weevil (Curculio caryae): H. bacteriophora

Ø Pine weevil (Hylobius abietis): S. carpocapsae, S. feltiae & H. downesi

Ø Plum weevil (Conotrachelus nenuphar): S. riobrave 355 strain

Ø Shore flies (Scatella stagnalis): H. megidis, S. carpocapsae, S. feltiae & S. anomaly

Ø Sod webworm (Herpetogramma phaeopteralis): S. carpocapsae All strain

Ø Stable fly (Stomoxys calcitrans): S. carpocapsae, H. bacteriophora & S. feltiae

Ø Strawberry root borer (Nemocestes incomptus): S. carpocapsae

Ø Sugarcane borer (Diaprepes abbreviatus): S. carpocapsae All strain

Ø Sweet potato weevil (Cylasformicarius elegantulus): S. carpocapsae All strain & H. bacteriophora HP88 strain

Ø Western flower thrips (Frankliniella occidentalis): H. bacteriophora, H. indica, H. marelata, S. abassi, S. arenarium, S. bicornutum, S. carpocapsae, S. feltiae

Ø White grubs (Amphimallon solstitiale): S. glaseri

Ø White grubs (Anomala orientalis): H. bacteriophora, H. megidis, H. zealandica, S. carpocapsae, S. glaseri, S. longicaudum, S. scarabae

Ø White grubs (Ataenius spretulus): H. bacteriophora, S. glaseri & S. scarabae

Ø White grubs (Costelytra zealandica): H. bacteriophora & S. glaseri

Ø White grubs (Cotinus nitida): H. bacteriophora, S. carpocapsae, S. feltiae, S. glaseri & S. scarabae

Ø White grubs (Cyclocephala borealis): H. bacteriophora, H. indica, H. marelata, H. megidis, H. zealandica, S. glaseri & S. scarabae

Ø White grubs (Cyclocephala hirta): H. bacteriophora, H. megidis, S. carpocapsae, S. feltiae, S. glaseri, S. kushidai, S. riobrave & S. scarabae

Ø White grubs (Cyclocephala lurida): H. bacteriophora, S. glaseri & S. scarabae

Ø White grubs (Cyclocephala pasadenae): H. bacteriophora, S. glaseri, S. kushidai & S. scarabae

Ø White grubs (Hoplia philanthus): H. megidis, S. feltiae & S. glaseri

Ø White grubs (Maladera castanea): H. bacteriophora, S. glaseri & S. scarabae

Ø White grubs (Melolontha melolontha): H. bacteriophora, H. marelata, H. megidis, S. arenaria, S. feltiae, S. glaseri & S. riobrave

Ø White grubs (Phyllophaga congrua): H. bacteriophora, S. glaseri & S. scarabae

Ø White grubs (Phyllophaga crinita): H. bacteriophora, S. glaseri & S. scarabae

Ø White grubs (Phyllophaga georgiana): H. bacteriophora, S. glaseri & S. scarabae

Ø White grubs (Rhizotrogus majalis): H. bacteriophora, H. megidis, H. zealandica, S. carpocapsae, S. feltiae, S. glaseri & S. scarabae

For more information on insect pathogenic nematodes read following books:

Ø Nematodes As Biocontrol Agents by Grewal, P.S. Ehlers, R.-U., Shapiro-Ilan, D. (eds.). CAB publishing, CAB International, Oxon.

Ø Entomopathogenic Nematodes in Biological Control by Gaugler, R. and Kaya, H. K. (eds.), CRC Press, Boca Raton

Ø Entomopathogenic Nematology by Gaugler, R. (Ed.), CABI