Aedes aegypti (Diptera : Culicidae) age determination by cuticular hydrocarbon analysis of female legs

We previously described methods for age-grading female Aedes aegypti (L.) b y gas chromatographic (GC) analysis of whole-body cuticular hydrocarbon pat terns. Two regression models were developed that were based on the age-depe ndent, relative abundance of 2 cuticular hydrocarbons, pentacosane (GC peak 1) and nonacosane (GC peak 5). We have refined this method so that only th e legs are required to age individual females. Two new regression models we re developed that also use the relative abundance of a 3rd cuticular hydroc arbon, octacosane (GC peak 4). These models improve the overall accuracy of the cuticular hydrocarbon method for aging female mosquitoes, especially f or order females from 132 to 165 degree-days (DD) of age (12-15 calendar da ys at 28 degrees C). The correlation coefficients (R-2) for the lest-fitted linear regression models for aging females from 0 to 132 and 0-165 DD were 0.80 and 0.81, respectively (P < 0.001 in all cases). The use of leg cutic ular hydrocarbons for estimating the age of female Ae. aegypti has a signif icant advantage over whole-body extracts as indicated by the decreased vari ability associated with the relative abundance of pentacosane and the expan ded range over which the models were able to predict age accurately by the addition of the relative abundance of octacosane.