Toxicity of commercial fungicides in relation to the larvae of Drosophila melanogaster Meigen (Diptera, Drosophilidae) and effect on the sex ratio

Bouillie bordelaise, Benlate, Euparène and Dithane M45 had no effects on Drosophila eggs. However, a post-hatching mortality was observed and, in all cases, a "dose effect" was established. There was a quick effect with Bouillie bordelaise, a slow and continued one with Benlate and Euparène, and the effect was delayed until the pupal stage with Dithane. Bouillie bordelaise, Benlate and Euparène slowed down the larval development and the emergence period was longer, according to the doses. Bouillie bordelaise was always the most toxic fungicide and Dithane the least one. The sex-ratio was not disturbed with Bouillie bordelaise. With Benlate and Euparène, the females were more sensitive than the males, while Dithane was more toxic towards males. Considering a same fungicide, a difference was exhibited according to the chosen criterion: Benlate caused an effect on larval mortality which was more important than its effect on the developing-time. Moreover, both carbamates, Benlate and Dithane, acted differently whatever their toxicity level.