Meeting Abstract

50.5  Saturday, Jan. 5  3-D flight trajectories vary with light level in the nocturnal sweat bee, Megalopta THEOBALD, J C*; COATES, M C; WARRANT, E J; WCISLO, W T; Univ. of California, Los Angeles; Lund University, Sweden; Lund University, Sweden; Smithsonian Tropical Research Institute, Panama jamiet@physci.ucla.edu

We examined how light limits the sweat bee Megalopta‘s (Hymenoptera: Halictidae) flight behavior by measuring flight times and corresponding light levels and comparing them with flight trajectories upon return to the nest. In contrast to most bees, Megolopta, flies in extremely dim light. Megalopta performs visually guided flight with apposition eyes, unlike most nocturnal insects which are equipped with superpositon eyes to greatly enhance light capture. We found the average time to land increased in dim light, an effect due not to slow approaches, but to circuitous approaches. Some landings, however, were quite fast even in the dark. To explain this, we examined the flight trajectories and found that in dim light, landings became increasingly error prone and erratic, consistent with repeated landing attempts. These data agree well with the premise that Megalopta uses visual summation, sacrificing acuity in order to see and fly at the very dimmest light intensities that its visual system allows. Here we speculate on differnt strategies Megalopta may use to accomplish this feat.