Nematodes are usually microscopic, thread-like, colorless and non-segmented roundworms without any appendages. There are harmful (e.g., plant- and animal-parasitic) and beneficial (e.g., entomopathogenic) nematodes. Plant-parasitic nematodes generally cause damage to crops and many other types of plants. Although majority of plant-parasitic nematodes are root feeders, they have different types of association with plants. For example, the root-knot (Meloidogyne sp) and cyst (Heterodera sp.) nematodes have endoparasitic association meaning they live and feed within the tissue of roots, tubers, buds, seeds. Nematodes including stuby-root (Trichodorus sp.), dagger (Xiphinema sp), needle (Longidorus sp), ring (Criconemella sp), stunt (Tylenchorhynchus sp), pin (Paratylenchus sp), and spiral (Helicotylenchus sp) have ectoparasitic association meaning they feed externally on roots through their walls. Some of the nematodes like the reniform (Rotylenchulus reniformis) have semi-endoparasitic association meaning these nematodes feed on the roots by penetrating their anterior (head) region into root tissue and leaving their posterior (tail) region remains outside of the root.
Plant parasitic nematodes
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- For the last several decades, entomopathogenic nematodes have been successfully used for the management of insect pests of many economically important crops (Grewal et al., 2005).
- As an additional benefit, several researchers including Fallon et al. (2002), Gouge et al. (1997), Grewal et al. (1997; 1999), Jagdale et al. (2002), Jagdale and Grewal (2008), LaMondia and Cowles (2002), Lewis et al. (2001), Lewis and Grewal (2005), Molina et al. (2007), Nyczepir et al. (2004), Perez and Lewis (2002), Perry et al. (1998) and Shapiro et al. (2006) have demonstrated that entomopathogenic nematodes can also be used as biological control agents to control plant-parasitic nematodes infesting different crops in the fields and greenhouses .
- To control plant- parasitic nematodes, entomopathogenic nematodes can be applied using standard spraying equipments used for application of chemical pesticides.
- Entomopathogenic nematodes are generally applied against plant-parasitic nematodes at the rate of 1 billion infective juveniles per acre but this rate can vary with both entomopathogenic nematode and plant- parasitic nematode species,
- Following are the examples of different species of entomopathogenic nematode that found to be successful in suppressing the population of different species of plant- parasitic nematodes.
- Steinernema carpocapsae can reduce the population of ring nematodes (Mesocriconema spp., Criconemoides spp.) by 65%.
- S. carpocapsae can reduce the population of stubby root nematodes (Paratrichodorus spp.) by 60%.
- S. carpocapsae can reduce the population of potato cyst nematodes (Globodera rostochiensis).
- S. carpocapsae can reduce the populations of foliar nematode Aphelenchoides fragariae
- Steinernema riobrave can reduce the population of stunt nematodes (Tylenchorynchu spp.) by 85%.
- S. riobrave can reduce the population of lance nematodes (Hoplolaimus spp.).
- S. riobrave can reduce the population of root-knot nematodes (Meloidogyne spp.) by 83%.
- S. riobrave reduced egg masses of root-knot nematodes (Meloidogyne spp.)
- S. riobrave can reduce the population of sting nematodes (Belonolaimus longocaudatus).
- Steinernema feltiae can inhibit hatching root-knot nematode eggs and infection by hatched infective juveniles of root-knot nematodes (Meloidogyne spp.).
- S. feltiae reduced egg masses of root-knot nematodes (Meloidogyne spp.) .
- S. feltiae can reduce the population of root-knot nematodes (Meloidogyne spp.).
- Steinernema glaseri reduced egg masses of root-knot nematodes (Meloidogyne spp.)
- Heterorhabditis bacteriophora can reduce the population of ring nematodes (Mesocriconema spp., Criconemoides spp.) by 80%.
- H. bacteriophora can reduce the population of stunt nematodes (Tylenchorynchus spp.) by 60%.
- H. bacteriophora can reduce the population of lesion nematodes (Pratylenchus pratensis).
- H. baujardi can inhibit hatching root-knot nematode eggs and infection by hatched infective juveniles of root-knot nematodes (Meloidogyne mayaguensis).
e Read following literature for more information on interaction between entomopathogenic nematodes and plant- parasitic nematodes:
1. Fallon, D.J., Kaya, H.K., Gaugler, R., Sipes, B.S., 2002. Effects of entomopathogenic nematodes on Meloidogyne javanica on tomatoes and soybeans. Journal of Nematology 34, 239-245.
2. Fallon, D.J., Kaya, H.K., Sipes, B.S., 2006. Enhancing Steinernema spp. suppression of Meloidogyne javanica. Journal of Nematology 38, 270-271.
3. Grewal, P.S., Ehlers, R.-U., Shapiro-Ilan, D.I. (Eds.), 2005. Nematodes As Biocontrol Agents. CABI Publishing, CAB International, Oxon, U.K.,
4. Grewal, P.S., Lewis, E.E., Venkatachari, S., 1999. Allelopathy: a possible mechanism of suppression of plant-parasitic nematodes by entomopathogenic nematodes. Nematology. 1, 735-743.
5. Grewal, P.S., Martin, W.R., Miller, R.W., Lewis E.E., 1997. Suppression of plant-parasitic nematode populations in turfgrass by application of entomopathogenic nematodes. Biocontrol Science and Technology 7, 393-399.
6. Jagdale, G.B., Grewal, P.S., 2008. Influence of the entomopathogenic nematode Steinernema carpocapsae in host cadavers or extracts from cadavers on the foliar nematode Aphelenchoides fragariae on Hosta. Biological Control 44, 13-23.
7. Jagdale, G.B., Somasekhar, N., Grewal, P.S., Klein, M.G., 2002. Suppression of plant parasitic nematodes by application of live and dead entomopathogenic nematodes on Boxwood (Buxus spp). Biological Control. 24, 42-49.
8. Lewis, E.E., Grewal, P.S., 2005. Interactions with plant-parasitic nematodes. In: Grewal, P.S., Ehlers, R.-U., Shapiro-Ilan, D.I. (Eds.), Nematodes As Biocontrol Agents. CABI Publishing, CAB International, Oxon, U.K., pp. 349-362.
9. Perry, R.N., Homonick, W.M., Beane, J., Briscose, B., 1998. Effects of the entomopathogenic nematodes, Steinernema feltiae and S. carpocapsae, on the potato cyst nematode, Globodera rostochiensis, in pot trials. Biocontrol Science and Technology 8:175 – 180.
10. Shapiro, D.I., Nyczepir, A.P., Lewis, E.E., 2006. Entomopathogenic nematodes and bacteria applications for control of the pecan root-knot nematode, Meloidogyne partityla in the greenhouse. Journal of Nematology 38, 449-454.