Several stored grain/product insect pests like Indian meal moth (Plodia interpunctella), Mediterranean flour moth (Ephestia kuehniella), Sawtoothed grain beetle (Oryzaephilus surinamensis), Mealworms (Tenebrio molitor), Red flour beetle (Tribolium castaneum) and Warehouse beetle (Trogoderma variabile) attack and destroy large quantities of stored grains and products during long-term storage in farm bins, grain processing facilities, warehouses, retail stores, and eventually also on the consumer shelves. The insect pests of stored grain/products have a major economic impact on the food industry due to the costs associated with their management, monitoring, rejection and return of contaminated shipments and failure to meet regulations that required to and pass inspections.  Therefore, there is a need to protect stored food products from attack by insects.  However, stored grain/product pests are generally difficult to control using traditional method as they hide in cracks and crevices, under perforated floors, and inside machinery used for processing of stored-products.  Chemical pesticides are not advisable to use against stored-product pests because of health and environment pollution risks.

The Indian meal moth (Plodia interpunctella): The larval stages infest and feed on different kinds of cereal grains, rice and processed dry foods like pasta, bread and spices.

The Mediterranean flour moth (Ephestia kuehniella): The larval stages mainly feed various types of flour.

The Sawtoothed grain beetle (Oryzaephilus surinamensis): This insect feed on broken seeds and seed germs.

The Mealworm (Tenebrio molitor): Larvae feed on flour and cereals.

The Red flour beetle (Tribolium castaneum): Feed on flour, cereal grains and dried food products like pasta, biscuits etc.

The Warehouse beetle (Trogoderma variabile): Larvae feed on dried cereal grains and food products such as noodles and spaghetti, and dried spices.

Entomopathogenic nematodes:

Entomopathogenic nematodes also called as insect-parasitic nematodes are commercially available and have potential to use as a biological control agent against above stated stored product pests because of their different host finding strategies.

For example, entomopathogenic nematodes, Steinernema carpocapsae use ambush foraging called “sit and wait” strategy to attack highly mobile insects including stored-product pests. After application, infective juveniles of Steinernema carpocapsae will generally remain near or at the surface of the stored-products.  When infective juveniles of Steinernema carpocapsae sense that there is an insect host passing by them, they will attack and infect it by standing on their tails (behavior called ‘nictation’) and jumping on the host.

Ambush foraging entomopathogenic nematode, Steinernema carpocapsae have a capacity to cause over 85% larval mortality of indian meal moths, mediterranean flour moths, mealworms and red flour beetles (Ramos-Rodriguez et al., 2006).

Entomopathogenic nematodes such as Heterorhabditis bacteriophora, Heterorhhabdtits megidis, Steinernema glaseri and Steinernema kraussei are considered as cruiser nematodes because they generally move actively in search of hosts and can easily find and attack their insect hosts that are hiding in deep in the soil or in case of stored-products hiding in cracks and crevices and under perforated floors. Cruiser nematodes never nictate but use carbon dioxide released by insect hosts as cues to attack them. Cruiser entomopathogenic nematodes, Heterorhabditis bacteriophora and Heterorhhabdtits megidis can kill larvae of Indian meal moth (Mbata and Shapiro-IIan, 2005).

Some entomopathogenic nematodes such as Steinernema feltiae and Steinernema riobrave have adapted a strategy in between ambush and cruise strategies called an intermediate strategy to attack both the mobile and sedentary/less mobile insects at the surface or deep in the soil and in case of stored-products, pests that hiding in cracks and crevices and under perforated floors or remaining at the surface of the product.

Intermediate foraging entomopathogenic nematode, Steinernema riobrave have a potential to kill over 65% larvae of indian meal moths, mediterranean flour moths, sawtoothed grain beetles, mealworms, red flour beetles and warehouse beetles (Ramos-Rodriguez et al., 2006).

Another intermediate foraging entomopathogenic nematode, Steinernema feltiae can cause over 90% larval mortality of only indian meal moths, mediterranean flour moths, red flour beetles (Ramos-Rodriguez et al., 2006) and over 79% larval mortality of the confused flour beetle,  Tribolium confusum (Athanassiou et al., 2008).

Publications:

Athanassiou, C.G., Palyvos, N.E. and 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.

Athanassiou, C.G., Kavallieratos, N.C., Menti, H. and Karanastasi, E. 2010.  Mortality of four stored product pests in stored wheat when exposed to doses of three entomopathogenic nematodes.   Journal of Economic Entomology 103: 977-984.

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-Rodriguez, O., Campbell, J.F. and Ramaswamy, S.B.  2006.   Pathogenicity of three species of entomopathogenic nematodes to some major stored-product insect pests. Journal of Stored Products 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.

Fayyaz S. and  Javed , S. 2009.  Laboratory Evaluation of Seven Pakistani Strains of Entomopathogenic Nematodes against a Stored Grain Insect Pest, Pulse beetle Callosobruchus chinensis (L.).  Journal of Nematology 41: 255-260.

• A presence of entomopathogenic nematode species including Steinernema khoisanae, Steinernema yirgalemense, Steinernema citrae, Heterorhabditis bacteriophora and Heterorhabditis zealandica have been reported in citrus orchards in the Western Cape, Eastern Cape and Mpumalanga provinces of South Africa (Malan et al., 2011).
• All the above nematode species have showed a very high virulence against false codling moth, Thaumatotibia leucotreta an economically important pest of citrus in South Africa.  For example, S. yirgalemense can cause over 74% mortality of both larval and pupal mortality of false codling moth when applied at the rate of 50-200 infective juveniles/ larval or pupal stages of false codling moth.
• Two entomopathogenic nematode species including S. yirgalemense and S. citrae were reported for the first time from South Africa (Malan et al., 2011).

Read following papers on entomopathogenic nematodes from South Africa

de Waal, J.Y., Malan, A.P. and Addison, M.F. 2011.  Evaluating mulches together with Heterorhabditis zealandica (Rhabditida: Heterorhabditidae) for the control of diapausing codling moth larvae, Cydia pomonella (L.) (Lepidoptera: Tortricidae).  Biocontrol Science and Technology 21: 255-270.

de Waal, J.Y., Malan, A.P., Levings, J. and Addison, M.F. 2010.  Key elements in the successful control of diapausing codling moth, Cydia pomonella (Lepidoptera: Tortricidae) in wooden fruit bins with a South African isolate of Heterorhabditis zealandica (Rhabditida: Heterorhabditidae). Biocontrol Science and Technology. 20: 489-502.

Hatting, J., Stock, S.P. and Hazir, S.  2009. Diversity and distribution of entomopathogenic nematodes (Steinernematidae, Heterorhabditidae) in South Africa.  Journal of Invertebrate Pathology 102: 120-128.

Malan, A.P., Knoetze, R. and Moore, S.D.  2011.  Isolation and identification of entomopathogenic nematodes from citrus orchards in South Africa and their biocontrol potential against false codling moth. Journal of Invertebrate Pathology 108: 115-125.

Malan, A.P., Nguyen, K. B. and Addison, M. F. 2006.  Entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) from the southwestern parts of South Africa. African Plant Protection 12: 65-69.

Malan, A.P., Nguyen, K.B., de Waal, J.Y. and Tiedt, L. 2008. Heterorhabditis safricana n. sp (Rhabditida : Heterorhabditidae), a new entomopathogenic nematode from South Africa. Nematology 10: 381-396.

Read following papers for more information.

Dembilio, O., Karamaouna, F., Kontodimas, D. C., Nomikou, M. and Jacas, J. A. 2011.  Short communication. Susceptibility of Phoenix theophrasti (Palmae: Coryphoideae) to Rhynchophorus ferrugineus (Coleoptera: Curculionidae) and its control using Steinernema carpocapsae in a chitosan formulation. Spanish Journal of Agricultural Research 9: 623-626.

Dembilio, O., Llacer, E., de Altube, M.D.M. and Jacas, J.A. 2010.  Field efficacy of imidacloprid and Steinernema carpocapsae in a chitosan formulation against the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae) in Phoenix. Pest Management Science 66: 365-370.

Application of Heterorhabditis indica and S. carpocapase at the rate 1 billion nematodes per hectare can reduce 72 and 50% population of alfalfa weevil, Hypera postica grubs, respectively.  Another entomopathogenic nematode, Steinemema thermophillum was also effective in killing H. postica grubs (Shah et al., 2011).

Read following paper for information on the effect of entomopathogenic nematodes on alfalfa weevil

Shah, N.K., Azmi, M.I. and Tyagi, P.K. 2011. Pathogenicity of Rhabditid nematodes (Nematoda: Heterorhabditidae and Steinernematidae) to the grubs of alfalfa weevil, Hypera postica (Coleoptera: Curculionidae). Range Management and Agroforestry 32: 64-67.

Read following papers for more information.

Susurluk, I.A., Kumral, N.A., Bilgili, U. and Acikgoz, E. 2011. Control of a new turf pest, Dorcadion pseudopreissi (Coleoptera: Cerambycidae), with the entomopathogenic nematode Heterorhabditis bacteriophora. Journal of Pest Science 84: 321-326.

Susurluk, I.A., Kumral, N.A., Peters, A., Bilgili, U. and Acikgoz, E. 2009.  Pathogenicity, reproduction and foraging behaviours of some entomopathogenic nematodes on a new turf pest, Dorcadion pseudopreissi (Coleoptera: Cerambycidae). Biocontrol Science and Technology 19: 585-594.

Please read following article for interaction between the lesser peachtree borer and entomopathogenic nematodes.

Cottrell, T. E., Shapiro-Ilan, D. I., Horton, D. L., and Mizell, R. F., III.  2011. Laboratory virulence and orchard efficacy of entomopathogenic nematodes against the lesser peach tree borer (Lepidoptera: Sesiidae).  Journal of Economic entomology 104: 47-53.

Read following paper for more information

Maketon, M., Hominchan, A. and Hotaka, D.  2010. Control of American cockroach (Periplaneta americana) and German cockroach (Blattella germanica) by entomopathogenic nematodes.  Revista Colombiana de Entomologia 36: 249-253.

Read following literature for information on the interaction between entomopathogenic nematodes and filbertworm.

Bruck, D.J. and Walton, V.M. 2007.  Susceptibility of the filbertworm (Cydia latiferreana, Lepidoptera:Tortricidae) and filbert weevil (Curculio occidentalis, Coleoptera: Curculionidae) to entomopathogenic nematodes. Journal of Invertebrate Pathology. 96: 93–96.

Chambers, U. Bruck, D.J., Olsen, J. and Walton, V.M. 2010.  Control of overwintering filbertworm (Lepidoptera: Tortricidae) larvae with Steinernema carpocapsae. Journal of Economic Entomology. 103: 416-422.

Read following papers for detail information on effect of entomopathogenic nematodes on the 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.

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.