frames of eggs were removed from the queen chambers they were transferred to a walk-in incubator and held at 34 °C and 60% relative humidity (normal brood nest conditions) for ~ 1 h while the distribution of eggs in cells was recorded. The distribution data were obtained by placing a transparent acetate sheet over the cells, then placing color-coded dots on the acetate surface over each cell with felt tip marking pens (Sharpie). Such recordings were made for other brood stages at selected times of critical development, viz., on the first, second, tenth and twentyfourth days after the eggs were laid. An additional recording of larval survival was made on the seventh day of development for brood combs that were treated in the larval stage. Brood for all treatments was maintained in populous nursery colonies in a queen- free compartment under identical conditions until it reached the capped stage and no longer required care by nurse bees. Then the brood was transferred to an incubator at 34 °C and 60% relative humidity where comb frames were placed in individual cages to retain adult bees during the time of emergence. Approximately 95% of the bees generated by eggs laid on any given day normally emerge as adult bees during a three-day period (21-23 days after the eggs were laid). During a four-day period (21-24 days) the emerged bees were brushed daily from the frames into polyethylene bags and were frozen for later population counts and examination for teratological effects. Cells containing brood that did not emerge by the 24th day were uncapped, and the degree of development was recorded. Bees that had reached the pupal stage were preserved in 95% ethanol for later examination. During all handling procedures care was exercised not to injure brood by jarring the frame. For example, bees were removed from combs by brushing rather than shaking the frame. Scheduling of all operations was such that, beginning on the 13th day after the queens were confined, and continuing until the 18th day, 12 combs per day of each of the three ages of brood (eggs, larvae, and pupae) were available for sham or microwave exposure at one of the six power densities. The source of microwave radiation was a 2.45 GHz continuous wave power supply unit capable of generating a maximum of 300 W at less than two percent ripple. Waveguides transmitted the microwave energy to a Narda 644 horn antenna mounted into the top of a rectangular exposure chamber (61 cm long and 61 cm wide). Walls of the chamber were lined with Eccosorb HT-99 (Emerson and Cuming). The base of the horn was 121 cm above the 61 x 61 cm Styrofoam treatment platform. Microwave energy entering the chamber was monitored continuously by a Boonton 41-4A detector. Periodically, a crystal detector (Hewlett-Packard) was substituted for the detector to check the waveform of power-supply current. Exposures at 25 and 50 mW/cm2 utilized the waveguide system whereas those at lower power densities were accomplished by adding an attenuator. Frames of comb were held in the normal vertical orientation on the treatment platform during all exposures. During treatment normal colony brood nest temperature (34 ± 1 °C) was supplied in both chambers. Temperatures within the microwave and sham chambers were measured by liquid crystal thermometers (American Thermometer Company) located on the treatment platform. Recordings were made at the beginning and end of each exposure. Air within the treatment chamber was removed by fans (Pamoter model 7606), and was conducted through an insulated duct to the sham chamber, then vented outdoors via an exhaust duct. Thus, any odors in the treatment chamber, including possible pheromones released by the bees, were also present in the sham chamber.
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