Publications internationales
Résumé: Oberon® is a commercial formulation of spiromesifen, a pesticide inhibitor of lipid biosynthesis via acetyl CoA carboxylase, widely used in agricultural crop protection. However, its mode of action requires further analysis. We currently examined the effect of this product on Drosophila melanogaster as a non-target and model organism. Different concentrations of spiromesifen were administered by ingestion (and contact) during pre-imaginal development, and we evaluated its delayed action on adults. Our results suggest that spiromesifen induced insecticidal activity on D. melanogaster. Moreover, spiromesifen treatment significantly increased the duration of larval and pupal development at all tested concentrations while it shortened longevity in exposed males as compared to control males. Also, pre-imaginal exposure to spiromesifen quantitatively affected fatty acids supporting its primary mode of action on lipid synthesis. In addition, this product was found to modify cuticular hydrocarbon profiles in exposed female and male flies as well as their sexual behavior and reproductive capacity.
Résumé: Spiromesifen (Oberon® 240 SC; concentrated solution; Bayer CropScience, Germany) a pesticide derived from spirocyclic tetronic acids, acts mainly though blocking lipid biosynthesis via acetyl-CoA carboxylase. However, its mode of action requires further analyses. This study aims to evaluate the sublethal effects of spiromesifen on the fruit fly Drosophila melanogaster. The treatment was carried out by topical application on newly moulted pupae using two concentrations (LD10 = 21.45 and LD25 = 39.53 μg a.i./pupa). Our results showed that the developmental duration of larvae and pupae were not significantly affected by treatment. However, spiromesifen caused delayed effects on flies that survived from treated pupae. Spiromesifen was found to decrease significantly both the morphometric measurements and the protein contents of ovaries. The protein pattern of ovaries showed a reduction in the number of protein bands affecting the progeny via vitellogenesis. Finally, compared to controls, spiromesifen decreased significantly the amounts of some cuticular hydrocarbons in treated female and male adults. Consequently, in response to the changes in cuticular hydrocarbons, their sexual behaviour was also affected. Our study brings new insights about the multiple effects and physiological consequences of disturbing lipid metabolism.
Résumé: Spiromesifen (Oberon® 240 SC), a pesticide widely used to control pests like mites and whiteflies, was investigated using Drosophila melanogaster Meigen, 1830 (Diptera, Drosophilidae) as a model organism. The compound was applied topically at two concentrations (LC10: 21.45 and LC25: 39.53 μg active ingredient/pupa), on newly molted pupae and assessed on morphometric measurements of ovaries and the progeny of surviving adults. Results showed that spiromesifen inhibited the growth and development of ovaries, reducing at the highest dose (LC25) the number of oocytes, the volume of basal oocytes and ovarian weight. Biochemical analysis revealed that the tested compound reduced the ovarian levels of carbohydrates and glycogen during the sexual maturation. Moreover, fecundity, fertility and number of descendants from parents that survived to the treatment of pupae were significantly reduced. The sex ratio determined indicated a significant decrease in treated series and males seemed more sensitive to spiromesifen than females. Lastly, the compound was found to affect the sexual behavior.