ence system. Also, they are environmentally and economically significant as the major insect pollinator of wild flora and cultivated crops that account for one-third of the nations food supply (8). Honey bees in immature stages are reared within nests that consist of multiple, vertically-oriented beeswax combs composed of hexagonal cells. Eggs are laid singly in these cells at the rate of several hundreds to 2000 daily, depending on the season and colony population. Developmental times of the immature stages are remarkably uniform in the nearly constant incubation temperature of 33-35 °C that is maintained by adult bees clustered over the combs. Eggs hatch three days after being laid, revealing tiny larvae that are fed hundreds of times by nurse bees during 5-6 days of development until the cells are sealed with beeswax caps on the 8-9th day after the eggs are laid. Larvae pupate on the 11th day and adults usually emerge on approximately the 21st day. METHODS AND MATERIALS Our study was designed as a 6x6x2x3 factorial. The factors were six queens, six treatment levels (0, 3, 6, 9, 25 and 50 mW/cm2), two exposure chambers (microwave and sham) and three stages of brood that were one (eggs), seven (larvae) and 14 (pupae) days old. To assure genetic variability, eggs were obtained from six queens chosen at random. A 6 x 6 Latin Square treatment design assured that treatments would be performed in a different order each day and that brood from each of the six queens would be exposed to all six levels of radiation during the six-day period when exposures were made. Concurrently with the microwave exposures, brood from the same queens was exposed in a sham treatment chamber, adjacent to and identical in construction to the microwave chamber, which received affluent air from the microwave treatment chamber. A total of 216 frames of brood were used during the study. All exposures were 30 min in duration. New brood combs were generated for this study by attaching beeswax comb foundation in small frames (Fig. 1) made of nonmetallic materials, which were inserted into standard honey bee colonies until comb construction was completed. Eggs of known age were obtained by confining each queen on two frames of comb within a chamber (14x12x16 cm) made of queen excluder material with openings that permitted the smaller worker bees to pass freely through the chamber walls while retaining the larger queen within. This chamber was placed in the center of the colony brood nest. Frames of comb containing eggs were replaced each day with empty combs. Distribution of eggs within the cells was controlled in part by temporarily covering the upper portion of each frame with 8 mesh screen wire to prevent access by the queen, thereby concentrating egg laying activities in the lower open cells. This procedure yielded two essentially identical combs of eggs, both genetically and structurally, from each queen on a daily basis. To obtain the 216 frames of brood needed for the study, queens in six colonies were confined to two frames of comb per day for 18 days. Because of daily fluctuations in egg laying of queens, three additional queens were confined so that combs of eggs would be available for substitution whenever any one of the six primary queens failed to fill two frames of comb with eggs on a particular day. When frames were placed in the queen chamber they were assigned randomly to microwave or to sham exposure groups and to an exposure condition based on the Latin Square design. As
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