Biological effects of neem (Azadirachta indica) seed oil on an egg parasitoid, Trichogramma chilonis
1999
Raguraman, S. | Singh, R.P.
Neem seed oil was tested at concentrations of 5.0, 2.5, 1.2, 0.6, and 0.3% for oviposition deterrence, feeding deterrence, toxicity, sterility and insect growth regulator effects against Trichogramma chilonis Ishii. Neem seed oil at 0.3% deterred oviposition (parasitization) by the parasitoid, but the sensitivity varied considerably both under choice and no-choice conditions. Neem seed oil also deterred feeding at or above 1.2% concentration both in choice and no-choice tests. In feeding toxicity tests, neem seed oil at 5% concentration caused <50% mortality to both males and females but in contact toxicity tests, females were affected sparing males. No sterility effect was observed when the parasitoid was fed with neem seed oil-treated honey. Both pre- and posttreatment of host eggs revealed no adverse effects on the development of the parasitoid. In view of the sensitivity of the parasitoid adults to oviposition deterrent and (mild) toxic effects of neem seed oil, it is suggested that for inundative release of the parasitoid T. chilonis pretreatment of the crop with neem extracts should be avoided.
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