EVALUATION OF NEEM AZADIRACHTA-INDICA SEED EXTRACTS AND OILS AS OVIPOSITION DETERRENTS TO NOCTUID MOTHS

Applications of three concentrations of oil-free neem seed extracts (A zadirachta indica A. Juss; Meliaceae) to cabbage plants in cages did n ot deter oviposition by individuals of three species of noctuid moths, Trichoplusia ni, Peridroma saucia, and Spodoptera litura. The concent rations used corresponded to 10, 50, and 100 ppm of the main active in gredient, azadirachtin. The total number of eggs laid per female, fema le longevity, and median day of oviposition were not affected. Sprays of the neem oil-based insecticide Margosan-O-R, and a 1% aqueous emuls ion of a refined neem seed oil similarly had no effect on any of the p arameters studied. However, a 1% crude oil emulsion significantly redu ced the proportion of eggs laid by S. litura on treated plants. Our re sults suggest that literature reports of significant neem-based ovipos ition deterrence to S. litura are the result of compounds that are rem oved by higher levels of processing and thus not likely to be found in most commercial neem seed formulations. Sprays consisting of highly p rocessed neem seed extracts, used at concentrations that provide larva l control, are unlikely to be generally effective as oviposition deter rents to noctuid pests.