Lethality of Imidacloprid and Fipronil on Apis mellifera: a retrospective on the French case
The aim of this study is to draw a retrospective analysis on the lethality of imidacloprid (Gaucho®) and fipronil (Régent® TS) on Apis mellifera between 1992 and 2016 in France. Early monitoring reports in the 1992-2002 period notified these two embedded insecticides to be at the origin of massive colony collapse disorders. Ecotoxicological analyses based on the LD50 of imidacloprid and fipronil highlighted their differential lethality by both contact (imidacloprid: 81 ng/honeybee vs fipronil: 5,9 ng/honeybee) and ingestion (imidacloprid: 3,7 ng/honeybee vs fipronil: 4,2 ng/honeybee) but failed to point imidacloprid’s high solubility as a higher lethal agent. Chemical properties and action mode of these two insecticides originated neural disfunction in the case of imidacloprid, and honeybee brood immune depression for fipronil. Despite the conduction of these monitoring reports and laboratory researches, Fipronil was completely banned in 2005 but Imidacloprid only in 2016.