Effects of halofenozide (RH-0345) on cuticular hydrocarbons of mosquito larvae of Culex pipiens

Abstract : Insect cuticular hydrocarbons are known to have a protection and a pheromonal role. Quantitative changes in the cuticular hydrocarbons of Diptera occur over time and were used in a preliminary attempt to age-grade of mosquitoes. Halofenozide (RH-0345) is an insect growth regulator belonging to the class of non-steroidal ecdysone agonists. In a previous study, halofenozide was found to be effective against larvae of Culex pipiens L. (Diptera: Culicidae) and exerted its toxicity primarily by the induction of a precocious lethal molting (Boudjelida et al., 2005). In this study, newly molted 4th instar larvae of C. pipiens were exposed to halofenozide (23% EC) for 24 h at LC50 (12.58 µg/l) and LC90 (28.58µg/l) concentrations under standard laboratory conditions according to WHO recommendations. Then, to better understand the mode of action of halofenozide, the profiles of the cuticular hydrocarbons in treated and control larvae were evaluated using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS).