Application of two-way hierarchical cluster analysis for the identification of similarities between the individual lipid fractions of Lucilia sericata.

Abstract

The composition of the cuticular and internal lipids of larvae and pupae of Lucilia sericata was studied using chromatographic techniques. The lipids from both stages of L. sericata had similar free fatty acid (FFA) profiles and also contained alcohols and cholesterol. The range of the number of C-atoms detected for these classes of compounds was to some extent similar in larvae and pupae, but the relative amounts of each class differed between stages. Saturated as well as unsaturated FFAs with even and odd numbered C-atom chains were present in both cuticular and internal lipids. The alcohol fractions of L. sericata were represented by free, straight-chain primary alcohols containing an even number of C-atoms. The lipid composition of male and female L. sericata adults and the hydrocarbon composition of all stages of L. sericata had previously been analyzed. To have a full overview of the lipid composition and to identify similarities or dissimilarities between the individual lipid fractions in this insect species, two-way hierarchical cluster analysis (HCA) was performed using also the data from these previous publications. The content of FFA 18 : 1 (n-9) was noticed to be very high in the cuticular fractions of larvae and pupae as well as in all internal fractions (male, female, larvae, and pupae) and low in the cuticular fractions of male and female imago. The contents of FFAs 16 : 0 and 16 : 1 (n-9), cholesterol, and the n-alkanes n-C31 , n-C29 , n-C27 , n-C25 , and n-C23 varied between particular fractions, whereas the amounts of other compounds were similar in all fractions.