Toxicity and bioaccumulation of fipronil in the nontarget arthropodan fauna associated with subalpine mosquito breeding sites.

In order to examine ecological impact of fipronil use for larval culicine control in natural hydrosystems, toxicity and bioaccumulation of this new insecticide were analyzed on aquatic species representative of the nontarget arthropodan fauna (nonculicine larval Diptera: Chaoboridae, Chironomidae; planktonic Crustacea: Cladocera, Copepoda, Ostracoda) associated with target larval mosquito populations in the subalpine breeding sites. Standard toxicological bioassays using fipronil aqueous solutions from 1 to 2000 nM indicated different sensitivity levels among species. Insecticide bioaccumulation analyses, using [(14)C]fipronil solutions in simplified laboratory ecosystem, also indicated large differences among species. These differences may come from biological parameters characteristic of each species. Taking into account these nontarget effects of fipronil, a possible strategy of use of this insecticide for integrated mosquito control management was proposed, which is based upon selective dietary absorption of the insecticide by larval Culicidae.