Today, I read a paper published in Journal of Pest Science by Khatri-Chhetri et al. (2011), who tested the efficacy of two newly isolated entomopathogenic nematode species from Nepal against white grub, Holotrichia longipennis.  This white grub is a very serious pest of many crops including black gram, cabbage, chilies, maize, millet, paddy soybean and tomato. Khatri-Chhetri et al. (2011) compared the efficacies of Nepalese strains of entomopathogenic nematodes including Steinernema lamjungense LMT5, S. lamjungense SS4, S. everestense DKP4 with other nematode species including S. abbasi CS1, S. sp. KL1, Heterorhabditis indica CK2 and H. indica CK6) and with an insecticide, chlorpyrifos against second third stages of white grub, Holotrichia longipennis. These researchers reported that when Nepalese entomopathogenic nematodes were applied at the rate of 2.5 billion nematodes per hectare, they were able to reduce over 73% larval populations of white grubs and these results were comparable with efficacy of traditional insecticide, Chlorpyrifos 19 weeks after nematode application. I found that these findings are very exciting because it is always difficult get over 50% mortality of any insect host when entomopathogenic nematodes are applied under field conditions. I think these researchers could have compared 3 and 9 week % corrected mortality data using repeated measure analysis, which would have gave them a better understanding about the nematode efficacy differences between two nematode application time intervals.

Publication:

Khatri-Chhetri, H.B., Timsina, G.P., Manandhar, H.K. and Moens, M. 2011. Potential of Nepalese entomopathogenic nematodes as biocontrol agents against Holotrichia longipennis Blanch. (Coleoptera: Scarabaeidae). Journal of Pest Science 84: 457-469.

Wireworm, Agriotes lineatus cause a tremendous loss to potato yields throughout the world. As biological control agent, entomopathogenic nematodes can serve as a safe alternative to chemical pesticides in managing wireworms and helping to increase potato yields.  It has been shown that the entomopathogenic nematode, Heterorhabditis bacteriophora can cause over 67% mortality of wireworm, Agriotes lineatus within three weeks of application (Ansari et al., 2009).

Literature

Ansari, M.A., Evans, M. and Butt, T.M. 2009. Identification of pathogenic strains of entomopathogenic nematodes and fungi for wireworm control. Crop Protection 28: 269-272.

Sugarcane is grown as an important cash crop in many countries but insect pests like the sugarcane billbug, Sphenophorus levis can cause a tremendous yield loss to this crop. Entomopathogenic nematodes have a great potential to use as a biological control agent against the sugarcane bill bugs. Recently, Giometti et al. (2011) reported that entomopathogenic nematodes including Steinernema brazilense strain IBCB n6 and three strains of Heterorhabditis sp. (IBCB n10, IBCB n24 and IBCB n44) were highly virulent causing over 60% mortality of adults of the sugarcane billbug. Sphenophorus levis.  

Publications:

Giometti, FHC, Leite, LG., Tavares, FM., Schmit, F.S., Batista, A. and Dell’Acqua, R. 2011.  Virulence of entomopathogenic nematodes (Nematoda: Rhabditida) against Sphenophorus levis (Coleoptera: Curculionidae).   Bragantia 70: 81-86.

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 warm-adapted entomopathogenic nematode Steinernema siamkayai Tiruchirappalli strain can cause 45-100% larval mortality of various insect species including Galleria mellonella, Spodoptera exigua, Ceratitis capitata, Cydia splendana and Tenebrio molitor when tested under laboratory conditions at temperatures between 15- 37C (Raja et al., 2011).
• Wax moth (Galleria mellonella) larvae are pests of honeycomb but are widely used as a model organism for laboratory study and in vivo production of entomopathogenic nematodes.
• Beet armyworm (Spodoptera exigua) is a noxious pest of many crops including beets, asparagus, beans, different Cole crops, potatoes, tomatoes, sorghum, cotton and different oilseed.  Larvae of beet armyworm feed voraciously on leaves and are known for complete defoliation of plant.
• Mediterranean fruit fly (Ceratitis capitata) is economically important pests of many fruit crops including citrus, peach, pear and apple. Fruit fly larvae feed inside the fruits and makes fruits unattractive for eating.
• Acorn moth (Cydia splendana) larvae mainly cause damage to oak and chestnuts.
• Mealworm (Tenebrio molitor) larvae are commonly used as feed for many pet animals such as fish, reptiles and birds. These larvae are also used to study and in vivo production of entomopathogenic nematodes.

Publications on Steinernema siamkayai

1. Adiroubane, D., Tamilselvi, R. and Ramesh, V.  2010. Efficacy of Steinernema siamkayai against certain crop pests. Journal of Biopesticides 3: 180 – 185.
2. Khatri-Chhetri, H.B., Waeyenberge, L., Manandhar, H.K. and Moens, M. 2010.  Natural occurrence and distribution of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) in Nepal. Journal of Invertebrate Pathology. 103: 74-78.
3. Raja, R.K., Sivaramakrishnan, S. and Hazir, S. 2011.   Ecological characterisation of Steinernema siamkayai (Rhabditida: Steinernematidae), a warm-adapted entomopathogenic nematode isolate from India. Biocontrol 56: 789-798.
4. Stock, S.P., Somsook, V. and Reid, A.P. 1998. Steinernema siamkayai n. sp. (Rhabditida: Steinernematidae), an entomopathogenic nematode from Thailand. Systematic Parasitology 41: 105-113.

• Colorado potato beetles (Leptinotarsa decemlineata) are a most damaging pest of potatoes but they can also cause a significant damage to tomatoes and eggplants.
• Generally, both adults and larvae feed voraciously on leaves causing hundreds of millions dollars in yield loss each year in the United States.
• Many chemical insecticides have been recommended to control these beetles but unfortunately beetles have an ability to develop resistance to insecticides.
• Entomopathogenic nematodes as biological control agents could provide an alternative to chemical pesticides in management of Colorado potato beetles.
• As entomopathogenic nematodes naturally found soil, they are very effective against soil dwelling stages of host insect pests.  For example, mature larvae of Colorado potato beetle that moves in the soil for pupation can be a very good target for entomopathogenic nematodes.
• Commercially available entomopathogenic nematode species including Steinernema carpocapsae, Steinernema feltiae, Heterorhabditis megidis, Heterorhabditis marelata and Heterorhabditis bacteriophora have showed a very high efficacy against adult, larval and prepupal stages of Colorado potato beetles when tested in soil under laboratory conditions.

Publications:

1. Ebrahimi, L., Niknam, G. and Lewis, E. E. 2011.   Lethal and sublethal effects of Iranian isolates of Steinernema feltiae and Heterorhabditis bacteriophora on the Colorado potato beetle, Leptinotarsa decemlineata.  Biocontrol 56: 781-788.
2. Ebrahimi, L.,Niknam, G.and Dunphy, G.B. 2011. Hemocyte responses of the Colorado potato beetle, Leptinotarsa decemlineata, and the greater wax moth, Galleria mellonella, to the entomopathogenic nematodes, Steinernema feltiae andHeterorhabditis bacteriophora . Journal of Insect Science 11, Article Number: 75.
3. Armer, C.A., Berry, R.E., Reed, G.L. and Jepsen, S.J. 2004.  Colorado potato beetle control by application of the entomopathogenic nematode Heterorhabditis marelata and potato plant alkaloid manipulation. Entomologia Experimentalis et Applicata. 111: 47-58.
4. Berry, R.E., Liu, J. and Reed, G. 1997.  Comparison of endemic and exotic entomopathogenic nematode species for control of Colorado potato beetle (Coleoptera : Chrysomelidae). Journal of Economic Entomology. 90: 1528-1533.
5. Cantelo, W.W. and Nickle, W.R. 1992. Susceptibility of prepupae of the Colorado potato beetle (coleoptera, chrysomelidae) to entomopathogenic nematodes (Rhabditida, Steinernematidae, Heterorhabditidae). Journal of Entomological Science. 27: 37-43.
6. Nickle, W.R., Connick, W.J. and Cantelo, W.W. 1994. Effects of pesta-pelletized Steinernema-carpocapsae (all) on western corn rootworms and colorado potato beetles. Journal of Nematology. 26: 249-250.
7. Trdan, S., Vidrih, M., Andjus, L. and Laznik, Z. 2009. Activity of four entomopathogenic nematode species against different developmental stages of Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera, Chrysomelidae. Helminthologia. 46: 14-20.

• 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.

Quantitative real-time PCR (qPCR) technique can be used for the identification of entomopathogenic nematodes in the both Heterorhabditidae and Steinernematodae families directly from soil samples.

Species specific primers and TaqMan (R) probes from the ITS rDNA region for the EPNs were used for the identification of four species of entomopathogenic nematodes including Heterorhabditis bacteriophora, Steinernema carpocapsae, Steinernema feltiae and Steinernema scapterisci (Campos-Herrera et al., 2011).

A publication on indentification of entomopathogenic nematodes using quantitative real-time PCR (qPCR) technique.

Campos-Herrera, R., El-Borai, F.E., Stuart, R.J., Graham, J.H. and Duncan, L.W. 2011.   Entomopathogenic nematodes, phoretic Paenibacillus spp., and the use of real time quantitative PCR to explore soil food webs in Florida citrus groves. Journal of Invertebrate Pathology 108: 30-39.

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.