Résumé
Honey bees are important pollinators and are often described as indicator species for the quality of the environment. Domestic honey bees have suffered significant losses over the last decades and insecticides are clear contributing factors to this decline. Bees intoxicated with deltamethrin, a widely used pyrethroid insecticide, exhibit symptoms of strong neuromuscular alterations. In order to better understand the modes of action of this molecule on bees, we characterized its effects on isolated antennal neurons and skeletal muscle fibers. Using the patch-clamp electrophysiological method, we monitored the effects of deltamethrin on voltage-gated sodium channels (NaVs) and on voltage-gated calcium channels (CaVs), which are responsible for action potentials in neurons and insect muscle fibers, respectively. Under voltage-clamp, deltamethrin clearly impeded neuronal NaVs function by slowing down their closure. The sodium deactivation current was altered in both a use-dependent and a concentration-dependent manner. Conversely, in muscle fibers, preliminary observations suggest that ionic current amplitudes through CaVs were not altered by similar concentrations of deltamethrin. Further analysis of the CaVs biophysical properties is needed to confirm this latter result and in particular to fully describe their voltage-dependency in the presence of the insecticide.