Honeybee locomotion is impaired by Am-CaV3 low voltage-activated Ca2+ channel antagonist

Voltage‐gated Ca 2+ channels are key transducers of cellular excitability and participate in several crucial physiological responses. In vertebrates, 10 Ca 2+ channel genes, grouped in 3 families ( Ca V 1, Ca V 2 and Ca V 3 ), have been described and characterized. Insects possess only one member of each family. These genes have been isolated in a limited number of species and very few have been characterized although, in addition to their crucial role, they may represent a collateral target for neurotoxic insecticides. We have isolated the 3 genes coding for the 3 Ca 2+ channels expressed in Apis mellifera . This work provides the first detailed characterization of the honeybee T-type Ca V 3 Ca 2+ channel and demonstrates the low toxicity of inhibiting this channel. Comparing Ca 2+ currents recorded in bee neurons and myocytes with Ca 2+ currents recorded in Xenopus oocytes expressing the honeybee Ca V 3 gene suggests native expression in bee muscle cells only. High‐voltage activated Ca 2+ channels could be recorded in the somata of different cultured bee neurons. These functional data were confirmed by in situ hybridization, immunolocalization and in vivo analysis of the effects of a Ca V 3 inhibitor. The biophysical and pharmacological characterization and the tissue distribution of Ca V 3 suggest a role in honeybee muscle function.