D3017: Effects of nest cavity diameter on body size in Megachile rotundata

The alfalfa leafcutting bee (Megachile Rotundata) is a solitary cavity nesting bee. Body size influences performance in many bee species, including foraging distance. In M. rotundata, body size has low heritability and is strongly influenced by the size of the larval provision, temperature, and nest size. Commercial nesting boxes have cavities that are seven millimeters in diameter. Our goal was to examine the effects that nest diameter has on M. rotundata by manipulating the size of cavities that are available for nesting. We will provide the bees with nesting cavities that vary in size from four to nine millimeters in one millimeter increments. We measured the following in the offspring: mass, wing area, intertegular span, sex, and diapause status. We also tested the preference of mothers for different nest cavity diameters. We found that the eight millimeter nests reared the largest bees while the four millimeter nests reared the smallest bees.