Cuticular wax of Epilachna varivestis

Abstract

Cuticular lipids of larvae, pupae and adults of the Mexican bean beetle ( Epilachna varivestis) have been examined using gravimetric and thin layer densitometric techniques. The effects of rearing on different hostplants and of rearing temperature on lipid composition were studied. Total lipid varied with developmental stage as well as hosplant. The amount of lipid extracted ranged from 3.0 mg/g wet weight, in the case of larvae reared on snapbeans in the field, to 5.2 mg/g wet weight for pupae reared in limas under field conditions. Total lipid increased with increasing temperature for larvae reared under controlled climatic conditions. Thin layer densitometry was used to quantify lipid classes. Epicuticular lipids included hydrocarbons, wax esters, triacylglycerols, fatty alcohols, free fatty acids, sterols, three unidentified materials and alkaloid(s). Lipids of larval and pupal stages were composed primarily of wax esters, hydrocarbons and fatty alcohols in roughly equal proportions; free fatty acids, triacylglycerols, sterols, alkaloid(s) and two unknown materials made up of the remainder. Adult cuticular lipids consisted mainly of hydrocarbons (49–60% of total lipid).