THE IMPACT OF ELECTRIC FIELDS ON HONEY BEES (TRANSMISSION LINES, SHOCK, CURRENT DENSITY).

摘要

Biological effects in honey bee colonies under a 765-kV, 60-Hz transmission line electric (E) field = 7 kV/m were confirmed using controlled dosimetry and treatment reversal to replicate findings within the same season. Hives in the same environment but shielded from E field are normal, suggesting effects are caused by interaction of E field with the hive. Bees flying though the ambient E field are not demonstrably affected.;Mechanisms to explain colony disturbance fall into two categories, direct perception of enhanced in-hive E fields, and perception of shock from induced currents. The same effects induced in colonies with total-hive E-field exposure can be reproduced with shock or E-field exposure of worker bees in extended hive entranceways (=porches). Full-scale experiments demonstrate bee exposure to E fields including 100 kV/m under moisture-free conditions within a non-conductive porch causes no detectable effect on colony behavior. Exposure of bees on a conductive (e.g. wet) substrate produces bee disturbance, increased mortality, abnormal propolization, and possible impairment of colony growth. Thresholds for effects caused by step-potential-induced currents are: 275-350 nA--disturbance of single bees; 600 nA--onset of abnormal propolization; and 900 nA--sting.;Hive exposure to 7 kV/m under a 765-kV/m line produces internal step-potential-induced currents and interchamber short-circuit currents of one-half to several microamperes; total hive currents by up to 100% (mu)A. Induced hive currents exceed empirical sting threshold by up to 100x and E-field-induced bee body currents by up to 1000x. Disturbance under a transmission line is primarily attributed to electric shock from induced hive currents. Enhanced intra-hive E fields (>100 kV/m) may contribute to possible altered behavior and miscommunication.;Different thresholds and severity of effects were found in colonies exposed to 7, 5.5, 4.1, 1.8 and 0.65 to 0.85 kV/m at incremental distances from the line. Most colonies exposed at 7 kV/m failed in 8 weeks and failed to overwinter at (GREATERTHEQ)4.1 kV/m. Data suggest the limit of a "biological effects corridor" lies between 15 and 27 m (4.1 and 1.8 KV/m) beyond the outer phase of the transmission line.