Bees and microshocks

We explain on our main page about bees that there is little evidence that the electric or magnetic fields from power lines affect bees directly, indeed there is some evidence that bees thrive on power line corridors.  But there can be an effect of the electric field on the hive.  It can induce voltages that give the bees small shocks.  This was investigated in a series of studies where tunnels were put at the hive entrance.  By comparing conducting and insulating tunnels, researchers could separate the effects of the induced voltages from any direct effect of the field.  We give the abstracts of those studies here.

This effects is easily prevented by appropriate earthing and screening.

Bioelectromagnetics. 1981;2(4):315-28.
Biological effects of a 765-kV transmission line: exposures and thresholds in honeybee colonies.
Greenberg B, Bindokas VP, Gauger JR.

Honeybee colonies exposed under a 765-kV, 60-Hz transmission line at 7 kV/m show the following sequence of effects: 1) increased motor activity with transient increase in hive temperature; 2) abnormal propolization; 3) impaired hive weight gain; 4) queen loss and abnormal production of queen cells; 5) decreased sealed brood; and 6) poor winter survival. When colonies were exposed at 5 different E fields (7, 5.5, 4.1, 1.8, and 0.65-0.85 kV/m) at incremental distances from the line, different thresholds for biologic effects were obtained. Hive net weights showed significant dose-related lags at the following exposures: 7 kV/m, one week; 5.5 kV/m, 2 weeks; and 4.1 kV/m, 11 weeks. The two lowest exposure groups had normal weight after 25 weeks. Abnormal propolization of hive entrances did not occur below 4.1 kV/m. Queen loss occurred in 6 of 7 colonies at 7 kV/m and 1 of 7 at 5.5 kV/m, but not below. Foraging rates were significantly lower only at 7 and 5.5 kV/m. Hive weight impairment and abnormal propolization occur at lower E-field intensity than other effects and limit the "biological effects corridor" of the transmission line to approximately 23 m beyond a ground line projection of each outer phase wire. Intrahive E fields of 15-100 kV/m were measured with a displacement current sensor. Step-potential-induced currents up to 0.5 microA were measured in an electrically equivalent bee model placed on the honeycomb in a hive exposed at 7 kV/m. At 1.8 kV/m body currents were a few nanoamperes, or two orders of magnitude lower, and these colonies showed no effects. E-field versus electric shock mechanisms are discussed.

 

Bioelectromagnetics. 1988;9(3):285-301.
Mechanism of biological effects observed in honey bees (Apis mellifera, L.) hived under extra-high-voltage transmission lines: implications derived from bee exposure to simulated intense electric fields and shocks.
Bindokas VP, Gauger JR, Greenberg B.This work explores mechanisms for disturbance of honey bee colonies under a 765 kV, 60-Hz transmission line [electric (E) field = 7 kV/m] observed in previous studies. Proposed mechanisms fell into two categories: direct bee perception of enhanced in-hive E fields and perception of shock from induced currents. The adverse biological effects could be reproduced in simulations where only the worker bees were exposed to shock or to E field in elongated hive entranceways (= tunnels). We now report the results of full-scale experiments using the tunnel exposure scheme, which assesses the contribution of shock and intense E field to colony disturbance. Exposure of worker bees (1,400 h) to 60-Hz E fields including 100 kV/m under moisture-free conditions within a nonconductive tunnel causes no deleterious affect on colony behavior. Exposure of bees in conductive (e.g., wet) tunnels produces bee disturbance, increased mortality, abnormal propolization, and possible impairment of colony growth. We propose that this substrate dependence of bee disturbance is the result of perception of shock from coupled body currents and enhanced current densities postulated to exist in the legs and thorax of bees on conductors. Similarly, disturbance occurs when bees are exposed to step-potential-induced currents. At 275-350 nA single bees are disturbed; at 600 nA bees begin abnormal propolization behavior; and stinging occurs at 900 nA. We conclude that biological effects seen in bee colonies under a transmission line are primarily the result of electric shock from induced hive currents. This evaluation is based on the limited effects of E-field exposure in tunnels, the observed disturbance thresholds caused by shocks in tunnels, and the ability of hives exposed under a transmission line to source currents 100-1,000 times the shock thresholds.

 

Bioelectromagnetics. 1988;9(3):275-84.
Exposure scheme separates effects of electric shock and electric field for honey bees, Apis mellifera L.
Bindokas VP, Gauger JR, Greenberg B.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.

 

Bioelectromagnetics. 1989;10(1):1-12.
Laboratory investigations of the electrical characteristics of honey bees and their exposure to intense electric fields.
Bindokas VP, Gauger JR, Greenberg B.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.

 

Bioelectromagnetics. 1989;10(1):1-12.
Laboratory investigations of the electrical characteristics of honey bees and their exposure to intense electric fields.
Bindokas VP, Gauger JR, Greenberg B.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.

 

Final rept. 1982-1995, IIT RESEARCH INST CHICAGO IL
ELF Communications System Ecological Monitoring Program
Zapotosky, J. E. ; Gauger, J. R. ; Haradem, D. P.The U.S. Navy has completed a program that monitored biota and ecological relationships for possible effects from exposure to electromagnetic (EM) fields produced by its Extremely Low Frequency (ELF) Communications System. Physiological, developmental, and ecological variables for abundant biota in upland, wetland, and riverine habitats near the ELF System were monitored from 1982 and 1993. Research teams from several universities measured biological and ecological variables at about the same time at treatment and control sites, before and after the transmitting facilities became fully operational. Spatial and temporal comparisons were made using analysis of variance and intervention statistical techniques. The response of variables to natural environmental and site factors were addressed in most analyses. Data collection for studies located near the Naval Radio Transmitting Facility (NRTF)-Clam Lake, Wisconsin, was completed, as scheduled, during 1989. Investigators concluded that there were no effects from intermittent or full operation of the transmitter. Data collection for studies near the NRTF-Republic, Michigan, were completed during 1993. There were no unequivocal effects on the variables monitored in Michigan. A few minor changes may have occurred; however, their implication is not indicative of adverse ecological significance.