Activity of spiromesifen on growth and development of Culex pipiens (Diptera: Culicidae): Toxicological, biometrical and biochemical aspects

Abstract

The present study aimed to evaluate the activity of spiromesifen, an insecticide belonging to the chemical group of spirocyclic tetronic/tetramic acid derivatives, against the most abundant and investigated mosquito species, Culex pipiens Linne, 1758 (Diptera, Culicidae). A commercial formulation of spiromesifen (OberonR 240 SC) was tested at different concentrations ranging between 238 and 1428 µg/L on newly molted fourth-instar larvae under standard laboratory conditions according to WHO recommendations. The effects were examined on the mortality, the morphometric measurements and the biochemical composition of body of larvae, respectively. The compound exhibited insecticidal activity and mortality occurred after earlier inhibition of their development or by their inability to complete their ecdysis. Moreover, it disturbed growth and several morphological aberrations were observed. It was also found to affect body volume, contents of carbohydrates, lipids and proteins, and their caloric indexes. Spiromesifen exhibited insecticidal activity against C. pipiens and affected the main biochemical components of body with a marked effect on lipids and malondialdehyde confirming its primary mode of action on lipid synthesis. However, it appears less potent than other insecticides tested such as the insect growth disruptors.