Archive

Interaction between entomopathogenic nematodes and mustard beetles- Nematodeinformation

It has been demonstrated that the virulence of Heterorhabditis indica and Heterorhabditis bacteriophora against the pupae of mustard beetle, Phaedon cochleariae was high at 30^oC but the virulence of Steinernema carpocapsae and Steinernema feltiae was high at 25^oC (Mahar et al., 2012).

Literature:

Mahar, A.N., Jan, N.D. and Mahar, A.Q. 2012.  Comparative effectiveness of entomopathogenic nematodes against the pupae of mustard beetle, Phaedon cochleariae F. (Chrysomelidae: Coleoptera). Pakistan Journal of Zoology 44: 517-523.

Control of cutworms with entomopathogenic nematodes- Nematode information

Cutworms are foliage feeding pest of turfgrass.  Moths of turfgrass cutworms emerge from overwintering pupae early in the spring and after mating they start laying about 1000-1200 eggs at tip of grass blades. Depending upon the temperature, eggs hatch within 10-12 days. After hatching from eggs, caterpillars (see photo of caterpillar) start feeding on turfgrass leaves and stems at night and hide under thatch during day time. During development all the stages (six instars) of caterpillars cause damage by cutting and chewing leaves and stems at the crown of turfgrasss until late summer completing 3-6 generations.

Entomopathogenic nematodes including Steinernema carpocapsae and Heterorhabditis bacteriophora have been proved to be effective when applied at rate of one billion nematode per acre. It is always advised to apply nematodes late in the evening to avoid exposure to UV light, which is detrimental to nematodes.

Entomopathogenic nematodes can kill turfgrass cutworms

Efficacy of entomopathogenic nematodes against white grub, Holotrichia longipennis

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.

An entomopathogenic nematode, Heterorhabditis atacamensis- Nematode Information

New entomopathogenic nematode species was found in the soil collected from Atacama Desert in Chile and was named after Atacama Desert as Heterorhabditis atacamensis. I like the way nematode taxonomists (Edgington et al., 2011) used individual morphological characteristics to differentiate this new species from other morphologically similar species of entomopathogenic nematodes. For example, these researchers showed that the H. atacamensis differed from H. marelatus, H. downesi and H. amazonensis based on position of hemizonid (a nematode sensory organ), position of excretory pore and female tail terminus shape, and number and position of genital papillae, respectively.  Using molecular techniques, Edgington et al. (2011) were also able to distinguish H. atacamensis from closely related entomopathogenic nematode species, H. safricana.

 Research Paper

Edgington, S., Buddie, A. G., Moore, D., France, A., Merino, L. and Hunt, D. J. 2011. Heterorhabditis atacamensis n. sp (Nematoda: Heterorhabditidae), a new entomopathogenic nematode from the Atacama Desert, Chile. Journal of Helminthology 85: 381-394.

Entomopathogenic nematodes and Wireworms, Agriotes lineatus- Nematode Information

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.

Entomopathogenic nematodes- Mode of Infection

In the soil environment, infective juveniles of entomopathogenic nematodes (Figure 1.) are always searching for the insect hosts to infect, kill, feed and reproduce.  Once the infective juveniles of both Steinernematid (Steinernema spp.) and Heterorhabditid (Heterorhabditis spp.) nematodes locate any larval, pupal or adult stages of their insect host, they will rush to find any easy entry routes/points to enter into the insect host body.  As shown in Figure 2, the infective juveniles of both Steinernema spp. and Heterorhabditis spp. generally use natural openings such as mouth, anus and spiracles/breathing pores (usually one pair of spiracles per body segment located laterally along the thorax and abdomen of  insects) of their hosts as main points of entry.  However, the infective juveniles of only Heterorhabditis spp. can also enter into host’s body by puncturing the inter-segmental membranes of the cuticle (see Figure 2).  The infective juveniles that enter via mouth and anus will end up in digestive track (gut) whereas those enter through spiracles will reach in tracheal tubes.  However, to kill their host successfully for food and development, the infective juveniles of both Steinernematid and Heterorhabditid nematodes eventually need to penetrate by puncturing digestive track (gut) or tracheal tubules (currently, the process of puncturing is unclear) into insect’s body cavity (an open circulatory system) and release symbiotic bacteria, Xenorhabdus spp. and Photorhabdus spp., respectively from their gut in insect blood generally called hemolymph.  In the blood, multiplying nematode-bacterium complex causes septicemia and kill their insect host usually within 48 h after infection.

To enlarge, click the pictures.

Fig. 1. Infective juveniles of entomopathogenic nematodes- Photo by Ganpati Jagdale

Fig. 2. Points of infection by entomopathogenic nematodes into body of their insect hosts: Photo by Ganpati Jagdale

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.

Enlarge the picture by clicking on it.

Infective juveniles of entomopathogenic nematodes- Photo by Ganpati Jagdale

Stored grain/ product pests: Nematode Information

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.

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.

Entomopathogenic nematodes and Colorado potato beetle

• 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.