RNAi knock-down of desat1 in oenocytes leads to a dramatic decrease in unsaturated hydrocarbons counter-balanced by an increase in saturated hydrocarbons. A. Percentages of different classes of hydrocarbons (dienes, monoenes, saturated, pheromones) in control (white) and RNAi (black) flies. B. Percentages of the specific hydrocarbons according to their class and their length. All the hydrocarbon differences between control (1407-GAL4/+) and desat1 knocked-down lines (1407-GAL4/UAS-desat1 RNAi) were significantly different (P < 0.001, Student's t-test).