Insect antifeedant and growth-regulating activities of salannin and other c-seco limonoids from neem oil in relation to azadirachtin

Abstract

The antifeedant and insect growth-regulating activities of salannin, nimbin, and 6-deacetylnimbin, in comparison with azadirachtin-A, have been studied against Spodoptera litura, Pericallia ricini, and Oxya fuscovittata. Salannin deterred feeding, delayed molt by increasing larval duration, caused larval and pupal mortalities, and decreased pupal weights in the two lepidopterans. Salannin also caused molt delays and nymphal mortalities in Oxya fuscovittata. The role of salannin and other compounds in conferring bioactivity, along with azadirachtin-A, to neem oil/neem seed extracts is emphasized.