Body Size and Flight Performance in the Native Pollinator, Osmia lignaria, Blue Orchard Bee

Native solitary bees provide important contributions to pollination regimes. To better understand pollinating capacity of Osmia lignaria, flight performance was examined in relation to body size. Two hypotheses were tested: Measurement of body size will vary in a natural population and larger body size will correlate with higher scores on flight performance.  Frozen samples were obtained through commercial sources and weight and body segment measurements were made using ImageJ Software.  Body size measurements included head width, head length, intertegular span, abdomen length, and abdomen width.  Flight performance was characterized as a function of wing area and body mass, using both the Extra Power Index, which is the energy used beyond hovering, and wing loading.  Females are heavier and larger than males and have slightly decreased power to fly compared to males.  However, females have higher wing loading and therefore are able to carry more pollen.  The first hypothesis was supported as there was variation in body size across the samples and not all body measurements were correlated.  The second hypothesis was not supported, as flight performance measures were lower in larger bees.  Further study of Osmia lignaria flight performance and pollination efficiency and species selection would benefit our understanding of native plant pollination in the region.