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Entomopathogenic nematodes and the sugarcane billbug, Sphenophorus levis- Nematode Information

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.

Entomopathogenic Nematodes- Nematode Information

Insect-parasitic nematodes that belong to both Steinernematidae and Heterorhabditidae families are also called as entomopathogenic nematodes because they cause disease to their insect hosts with the help of mutualistically associated symbiotic bacterial pathogens. The entomopathogenic nematodes that belong to families Steinernematidae (Steinernema spp.) Heterorhabditidae (Heterorhabditis spp.) are symbiotically associated with species specific bacteria, Xenorhabdus spp. and Photorhabdus spp., respectively.  The infective juveniles of entomopathogenic nematodes from both these families carry hundreds of specific bacterium cells in their guts and use them to cause disease and kill their insect host within 48 hours after infection.

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Infective juveniles of entomopathogenic nematodes- Photo by Ganpati Jagdale

Entomopathogenic nematodes and their symbiotic bacteria- Nematode Information

Molecular studies demonstrated that the closely related Photorhabdus, symbiotic bacteria of Heterorhabditis nematodes and Xenorhabdus, symbiotic bacteria of Steinernematid nematodes have developed totally different molecular strategies for the same objective of virulence to insects and symbiosis with the nematode.

These findings were presented by An, R. and Grewal, P.S. at the 50th annual meeting of the Society of Nematologists held in Corvallis, Oregon from July 17-20, 2011.

An entomopathogenic nematode, Steinernema siamkayai

• 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.

• 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.

Entomopathogenic nematodes and qPCR

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.

Heterorhabditis indica and Steinernema carpocapsae for controlling alfalfa weevil

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.

The application of an entomopathogenic nematode Heterorhabditis bacteriophora at the rate of 0.5 million infective juveniles per square meter can significantly reduce the population of Dorcadion pseudopreissi infesting turf grass (Lolium perenne) in the field (Susurluk et al. (2011).

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.

It has been demonstrated that entomopathogenic nematodes are attracted to herbivore-induced volatile organic compounds (VOCs) from plants when fed upon by their insect pests.   Thus these attracted nematodes can attack and kill the insects present in the vicinity of plants.

Please read following papers for more information on VOCs released by plants and nematode attraction.

Ali, J.G., Alborn, H.T. and Stelinski, L.L. 2011. Constitutive and induced subterranean plant volatiles attract both entomopathogenic and plant parasitic nematodes. Journal of Ecology 99: 26-35.

Rasmann, S., Erwin, A.C., Halitschke, R. and Agrawal, A.A. 2011. Direct and indirect root defenses of milkweed (Asclepias syriaca): trophic cascades, trade-offs and novel methods for studying subterranean herbivory.  Journal of Ecology 99: 16-25.

Recently, Negrisoli et al. (2010) demonstrated that entomopathogenic nematodes including Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri were found to be compatible with many insecticides including chlorpyrifos, deltamethrin, lufenuron, deltramethrin + triazophos, diflubenzuron, gamacyhalothrin, lambdacyhalothrin, spinosad, cypermethrin, triflumuron, and permethrin under laboratory conditions.

Read following paper for more information compatibility of entomopathogenic nematodes with insecticides.

Negrisoli, A.S., Garcia, M.S., Negrisoli, C.R.C.B. 2010.  Compatibility of entomopathogenic nematodes (Nematoda: Rhabditida) with registered insecticides for Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) under laboratory conditions.  Crop Protection 29: 545-549.