Oviposition deterrents from the egg masses of the adzuki bean borer, Ostrinia scapulalis and Asian corn borer, O. furnacalis

Abstract

AbstractBioassays using gravid females of the adzuki bean borer, Ostrinia scapulalis (Walker), and the Asian corn borer, O. furnacalis (Guenée) (Lepidoptera: Crambidae), showed that the presence of an egg mass of a conspecific deters oviposition. Volatile chemicals emanating from the egg mass were responsible for the deterrence, and these deterrents could be extracted from the egg mass with hexane. When fractionated using a Sep‐Pak® Plus NH2 cartridge, the deterrents were eluted with a 98 : 2 mixture of diethyl ether and acetic acid (polar lipid fraction). The polar lipid fraction contained free fatty acids with 14–20 carbons, and palmitic acid, palmitoleic acid, and oleic acid were predominant. A blend of all identified fatty acids, a blend of six major fatty acids (palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids), a blend of the two Z‐9‐alkenoic acids (palmitoleic and oleic acids), palmitoleic acid alone, and oleic acid alone showed deterrence against O. scapulalis which was comparable to that provoked by the full egg extract. The dose‐dependency of the deterrent effects of palmitoleic acid and oleic acid was verified in O. scapulalis. The binary blend of palmitoleic acid and oleic acid was also confirmed to deter oviposition in O. furnacalis.