Colorimetric surface lipid quantification in Drosophila

Insects are covered with free neutral cuticular hydrocarbons (CHC) that may be linear, branched, and unsaturated and vary in their chain length. The CHC composition is species‐specific and contributes to the adaptation of the animal to its ecological niche. Commonly, CHCs contribute substantially to the inward and outward barrier function of the cuticle and serve pheromonal communication. They are generally determined by gas‐chromatography, a time‐consuming method requiring detailed expertize, but it is not available in many laboratories. Here, we report on the establishment of a colorimetric method allowing semi‐quantitative determination of unsaturated CHCs in Drosophila flies. This method is based on the in vitro reaction of vanillin with double bounds in lipid molecules in an acidic solution to generate a reddish color. We found a robust correlation between gas chromatographic and vanillin‐colorimetric data on unsaturated CHCs amounts in single flies. As the role of unsaturated CHCs in the performance of insects in their environment is only partly understood, we think that this novel method would allow fast and broad analyses of this type of CHCs in insects both in the field and in laboratories and thereby contribute to a substantial improvement in the investigation of this matter. Quantification of insect cuticular hydrocarbons (CHC) is usually done by gas chromatography. Here, we present a simple protocol for CHC quantification by vanillin colourimetry. Highlights Using a simple chemical reaction between lipids and vanillin, we quantify cuticular hydrocarbons (CHCs) in Drosophila species This method is sensitive for single flies This method allows fast and easy quantification of CHCs