Hydrocarbon composition of the integument, fat body, hemolymph and diet of the tobacco hornworm

Abstract Gas-liquid chromatographic analysis of the hydrocarbon fraction of the integument, fat body, and hemolymph of the tobacco hornworm, Manduca sexta (Johannson), showed that the major hydrocarbons were both straight and branched alkanes. Heptacosane (9.8%) was the major n -alkane in the integument, and pentacosane was the major n -alkane in the fat body and hemolymph, 9.7 and 4.2%, respectively. The major n -alkane in the diet was nonacosane (17.5%). Branched alkanes, mono-, di-, and trimethylpentatriacontanes, with equivalent chain lengths between 35 and 36 made up 7.6% of the integument, 17.9% of the fat body, and 34.2% of the hemolymph hydrocarbons; branched alkanes, probably mono-, di-, and trimethylheptatriacontanes, with equivalent chain lengths between 37 and 38 made up 7.4% of the integument, 18.2% of the fat body, and 25.4% of the hemolymph hydrocarbons. The absence of these branched alkanes from the diet indicated that the tobacco hornworm must be capable of the biosynthesis of these branched hydrocarbons.