[Biochemistry of the developmental cycle of Triatoma infestans. VII. Lipid composition of the cuticle surface extracted with hexane].

The lipid composition of Triatoma infestans (vinchuca) epicuticle was studied. The insect lipids were extracted with hexane and fractionated by chromatography. Long chain fatty alcohols, hydrocarbons, waxes, triacylglycerols, diacylglycerols, free fatty acids, cholesterol, cholesterol esters and monoacylglycerols were detected. The composition of fatty acids, hydrocarbons and alcohols was studied by gas-liquid chromatography and mass spectrography. Linear and branched hydrocarbons were separated. Both types had an uneven number of up to 41 carbons. The predominant straight-chain hydrocarbons were in the range of 27 to 33 carbons. The branched hydrocarbons identified were 2-methyl, 3-methyl and internally branched monomethyl-alkanes and dimethyl-alkanes. The fatty alcohols identified had a straight chain of 16 to 34 carbons with predominance of 28 to 34 specimens. In the different fractions of esterified fatty acids and in the free acids two groups were detected: one formed by acids of 16 to 18 carbons saturated and non-saturated, and another by very long chain saturated acids of 24 to 32 carbons. The presence of alcohols, hydrocarbons and waxes, constituted mainly by long and saturated chains, conveys to the cuticle high resistance to physical and chemical aggressors of the environment.