Effect of ethyl acetate on vitality and virulence of entomopathogenic nematode species

Abstract EN

Entomopathogenic nematodes (EPNs) are the most important agents used in classical and augmentative biological control.

The aim of this research work is to study, the effect of different concentrations of ethyl acetate (EA) on survival and virulence of two Egyptian isolates of the EPNs, Heterorhabditis indica Poinar, Karunakar and David (Rhabditida: Heterorhabditidae) and Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae) in laboratory assays.

EA showed a nematicidal effect against both species at a concentration higher than 0.1%.

Infective juveniles (IJs) of H.

indica were much more sensitive to the lethal effect of EA than S.

carpocapsae.

The medium lethal concentration (LC50) of EA for H.

indica treated for 24 hrs.

was nearly four times less than that of S.

carpocapsae.

In contrary, EA at low concentrations increased EPNs virulence by enhancing the ability of IJs to penetrated and kill the host and by increasing the proportion of both actively moving IJs in H.

Indica and jumper “sprinter” IJs in S.

carpocapsae.

It is suggested that the lethal effect of EA on Entomopathogenic nematode (EPN) could be related to the damage of the nematode sensory apparatus due to its neurotropic effects.

The activation effect of lower concentration on EPNs could be due to their stimulation to nervous receptors in the amphidial channel and channel un-blockage which increase the sensorimotor reactivity of nematode.

The overall results suggested that EA at very low concentration is a promising candidate for EPNs activation prior field application.