Exposure scheme separates effects of electric shock and electric field for honey bees, Apis mellifera L

Mechanisms to explain disturbance of honey bee colonies under a 765-kV, 60-Hz transmission line [electric (E) field = 7 kV/m] fall into two categories: direct bee perception of enhanced in-hive E fields, and perception of shock from induced currents. The same adverse biological effects previously observed in honey bee colonies exposed under a 765-kV transmission line can be reproduced by exposing worker bees to shock or E field within elongated hive entranceways (= tunnels). Exposure to intense E field caused disturbance only if bees were in contact with a conductive substrate. E-field and shock exposure can be separated and precisely defined within tunnels, eliminating dosimetric vagaries that occur when entire hives are exposed to E field.     

Laboratory investigations of the electrical characteristics of honey bees and their exposure to intense electric fields

Bees exposed to 60-Hz electric (E) fields greater than 150 kV/m show field-induced vibrations of wings, antennae, and body hairs. They also show altered behavior if exposed while in contact with a conductive substrate. Measurements indicate that approximately 240 nA is coupled to a bee standing on a conductive substrate in a 100-kV/m E field. In lab experiments, bee disturbance and sting result from exposure to E field greater than 200 kV/m (bee current greater than 480 nA) and reduced voluntary movements at greater than 300 kV/m (greater than 720 nA bee current) only if the bee is on a conductive substrate. It is hypothesized that in the latter situation coupled bee current drains through the lower thorax and legs to the conductive substrate, and that the resulting enhanced current density in these regions is the cause of observed responses. The observation that bees exposed to intense E fields on an insulator show vibration of body parts but no behavioral response suggests that vibration contributes little to the disturbance of bees in intense E fields. Lab measurements of bee impedance from front-to-rear leg pairs were made on wet and dry conductors. Measurements validate the selection of 1 M omega as a middle value for bee impedance used in the design of devices used to generate step-potential-induced currents in bees.