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Soil is the natural habitat of entomopathogenic nematodes. As it is difficult to find free-living nematodes in soils, and to find insects naturally parasitized by NEPs, their search is carried out using the "Galleria trap" (Mracek, 1980). It consists of burying a pierced container - a tea ball, a pierced eppendorf tube - in the soil (10, 20 or 30 cm deep) in which an insect larva has been placed. Galleria mellonella (hive moth) is the model insect used as prey because it is known to be susceptible to EPNs (Ali et al, 2008). However, any other insect larva can be used in the same way. After a few days (5 to 8 days), the traps are collected on site in order to detect the presence of EPNs in the insect cadavers. Insect corpses parasitized by moulds are removed.

The others are placed on a collection device (A) in order to collect the IJs emerging from the cadaver in a liquid. These are preserved after filtration (B) at low temperature (8°C for Steinernema and 15°C for Heterorhabditis) for several months in aqueous medium at a concentration of 300-5000 IJs/mL (C)(Kaya and Stock, 1997). The trapped nematodes will then be identified by sequencing the ITS regions from the extracted gDNA (Malan et al, 2011).

Bibliography

Ali, S.S., Pervez, R., Abid Hussain, M., Ahmad, R. 2008. Susceptibility of three lepidopteran pests to five entomopathogenic nematodes and in vivo mass production of these nematodes. Archiv Phytopathol Plant Prot, 41, 300-304. DOI : 10.1080/03235400600759396.

Kaya, H.K. and Stock, P. 1997. Chapter VI - Techniques in insect nematology, Editor(s): Lawrence A. Lacey, Manual of Techniques in Insect Pathology, Academic Press, 1997, Pages 281-324, ISBN 9780124325555, DOI : 10.1016/B978-012432555-5/50016-6.

Mracek, Z. 1980. The use of « Galleria traps » for obtaining nematode parasites of insects in Czechoslovakia (Lepidoptera : Nematoda, Steinernematidae). Acta Entomol Bohemoslov, 77, 378-382.

Malan, A.P., Knoetze, R., Moore, S.D. 2011. Isolation and identification of entomopathogenic nematodes from citrus orchards in South Africa and their biocontrol potential against false codling moth. J Invertebr Pathol, 108, 115-125. DOI : 10.1016/j.jip.2011.07.006.