Toxicity of some new insecticides against Trichogramma chilonis (Hymenoptera: Trichogrammatidae) under laboratory and extended laboratory conditions.

Studies on the toxicity of some new insecticides against Trichogramma chilonis were carried out under laboratory and extended laboratory conditions following the guidelines recommended by International Organization for Biological Control (IOBC). Field Recommended Concentrations (FRCs) of six insecticides viz., emamectin benzoate, lufenuron, flubendiamide, spinosad, indoxacarb and neem oil were tested against all the life stages of the parasitoid under laboratory conditions. Persistent toxicity of the insecticides against the most susceptible life stage (adult) of the wasp was also determined. Results regarding the effects of the insecticides on the different life stages of T. chilonis revealed that flubendiamide was the most selective of all the tested insecticides for the development, survival and fecundity of the wasp. Spinosad, closely followed by emamectin benzoate severely curtailed adult survival and fecundity and to a lesser degree, the development of immature stages inside host eggs. Indoxacarb was also recorded as slightly harmful to all, except the egg stage of the wasp. Lufenuron exhibited significantly higher level of toxicity against the larval stage. Neem oil was harmless to the eggs, pupae and adults but exerted slightly harmful effects on larval development and female fecundity. Persistency test showed that flubendiamide and lufenuron were short lived, indoxacarb was slightly persistent and spinosad and emamectin benzoate were classified as moderately persistent. On the basis of this study, it could be concluded that flubendiamide is considerably safe, neem oil, indoxacarb and lufenuron are mildly toxic for the bio-control agent, while spinosad and emamectin proved highly toxic of all the insecticides.