Comparison of current and historic wild bee body length, head width, and intertegular distances

Abstract

Native bees are critical pollinators that all life depends on. Body size of of pollinators can influence fitness of individual bees and pollination effectiveness. This study investigated the change in body length, intertegular distance, and head width in several species of bees. Intertegular distance is the space between a bee’s wing bases or tegulae, and can be used to estimate bee body size. The literature has not addressed a comparison study with these measurements in mind. Global changes such as climate and land-use change may influence bee body size may change more over time with successional change with warming temperatures. Some bee species depend only on single species of flowers, or nest in stem cavities, so their bodies must coevolve with that plant species. Seven species of bees were selected for this study from Hennepin, Ramsey, Anoka, and surrounding counties. Current bees from the Minnesota Bee Survey and historical bees from the University of Minnesota Insect Collection were used for this comparison study. Over 300 bees were measured and included historical bees from the early 1900s to the 1940s and current bees from the 1990s to 2016. Then a two-tailed t-test was used to determine if bee body length, head width, and intertegular distances had changed over time. The preliminary results from a t-test have indicated the changes of body lengths on these species of bees was minimal and statistically insignificant, though these findings are still useful and can be applied to future research.