CUTICULAR LIPIDS OF LARVAE AND ADULTS OF THE CIGARETTE BEETLE, LASIODERMA-SERRICORNE

There were qualitative and quantitative differences between the cuticular lipids extracted from the larval and adult stages of the cigarette beetle, Lasioderma serricorne. Triacylglycerols were the major components in the larval surface lipids, but the amount of cuticular hydrocarbon present in the larva increased fourteen-fold on a per insect basis to become the predominant lipid component in the adults. The composition of the free fatty acids was similar in both stages. n-Alkanes constituted 84% of the larval hydrocarbons but decreased to 17% in the adults. Conversely, branched-chain alkanes made up 83% of the adult hydrocarbon fraction. n-Tritriacontane (37% of the total hydrocarbon fraction) was the major larval hydrocarbon. GLC analysis of the adult hydrocarbons showed two major peaks, one a mixture of 11-, and 13-methylnonacosane and another a mixture of 3-methylnonacosane and 11,15-dimethylnonacosane. These two peaks account for 36% of the adult hydrocarbons. A series of internally branched dimethylalkanes in which the methyl groups were on adjacent carbons was identified in the cuticular lipids of the larvae of the cigarette beetle. This is the first time that such compounds have been found in insects. 11,12-Dimethyltritriacontane, 11,12- and 12,13-dimethyltetratriacontanes, 11,12- and 13,14-dimethylpentatriacontanes, and 11,12- and 13,14-dimethylheptatriacontanes were identified. 4-Methylhexacosane and 4-methyloctacosane were identified in the cuticular lipids of adults of L. serricorne. Such compounds have not previously been reported as specific components of cuticular hydrocarbons from insects. © 1979.