Entomopathogenic Nematodes,Steinernema,Xenorhabdus,Heterorhabda,Photorhabdus,Nematode,Juvenile

Entomopathogenic Nematodes

Entomopathogenic Nematodes
Entomopathogenic nematodes belonging to the family Steinernematidae and Heterorhabditidae have emerged as biocontrol agents. Both have a third stage infective juvenile (IJ) which is a non-feeding larval stage and adapted for long-term survival in the soil. They are symbiotically associated with their respective bacterium, Steinernema with Xenorhabdus and Heterorhabda with Photorhabdus which causes rapid death of the insect host.

Each nematode species has a specific association with one bacterial species. IJ of certain species actively seek out for their host and exhibit a strategy like 'hunter'. Others wait for their prey and are designated as ambusher'. Nematodes of both the genera are easy to produce on large scale in liquid medium and are safe to humans.

In general, the IJ that are present in the soil are always in resting stage. When an insect host is present in the soil, the IJ moves towards the host.

Firstly, they find the host. Secondly, they penetrate into the suitable hosts through natural openings; by punching the host cuticle and finally, the IJs have to overcome the insect defence system and start multiplying.

The IJs release the symbiotic bacteria and the insects die 2-4 days after infection. Nematodes are able to persist for a long time in the environment. Persistence is the measure of the number of live nematodes present in the soil, e.g. Steinernema scapterisei are infective to mole crickets.

Index >> Applications of Microbial Interactions >> Entomopathogenic Nematodes

Entomopathogenic Nematodes