S. Raguraman et Rp. Singh, Biological effects of neem (Azadirachta indica) seed oil on an egg parasitoid, Trichogramma chilonis, J ECON ENT, 92(6), 1999, pp. 1274-1280
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 ins
ect growth regulator effects against Trichogramma chilonis Ishii. Neem seed
oil at 0.3% deterred oviposition (parasitization) by the parasitoid, but t
he sensitivity varied considerably both under choice and no-choice conditio
ns. 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 co
ntact toxicity tests, females were affected sparing males. No sterility eff
ect was observed when the parasitoid was fed with neem seed oil-treated hon
ey. Both pre- and posttreatment of host eggs revealed no adverse effects on
the development of the parasitoid. In view of the sensitivity of the paras
itoid adults to oviposition deterrent and (mild) toxic effects of neem seed
oil, it is suggested that for inundative release of the parasitoid T. chil
onis pretreatment of the crop with neem extracts should be avoided.