Antifeedant and insecticidal properties of azadirachtin to the European Corn Borer, Ostrinia nubilalis
1985
Arnason, J.T. | Philogène, B.J.R. | Donskov, N. | Hudon, M. | McDougall, C. | Fortier, G. | Morand, P. | Gardner, D. | Lambert, J. | Morris, C. | Nozzolillo, C.
Azadirachtin, a triterpenoid substance from the neem tree, Azadirachta indica A. Juss., Meliaceae, was evaluated for its antifeedant and insecticidal properties to the European corn borer Ostrinia nubilalis Hübner. The 50% protective concentration for larval feeding on treated corn disks (PC₅₀) was 3.5 ppm for neonate larvae and 24 ppm for third instar larvae. Azadirachtin severely reduced larval growth at 1 and 10 ppm in a meridic diet and eventually caused 100% mortality at 10 ppm and 90% at 1 ppm. At 0.1 ppm azadirachtin showed no significant effect on larvae but altered the sex ratio in favor of male moths during adult emergence and arrested oviposition of female moths. Nutritional indices for naive and habituated third instar larvae suggested that reduction of growth was due to toxicity as shown by a lowered efficiency of conversion in the azadirachtin treated groups, rather than changes in digestibility. No clear evidence of tolerance was observed in the habituated group. The data suggest that at 10 ppm azadirachtin is an effective botanical insecticide for control of O. nubilalis.
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