Meeting Abstract
Systropha curvicornis and Lasioglossum malachurum are two bees that both forage on field bindweed (Convolvulus arvensis). Observations suggested that S. curvicornis forages on pollen and nectar while L. malachurum only collects pollen. Our goal was to compare foraging behaviors to test the hypothesis of dietary niche separation between the two species. As a specialist, we expected a shorter handling time per flower for S. curvicornis than the generalist L. malachurum. We also predicted S. curvicornis to have shorter visit times in flowers when either pollen or nectar was absent but L. malachurum to have shorter handling times only when pollen was absent. We observed bees under control, pollen removal, and nectar removal conditions. L. malachurum had longer handling times than S. curvicornis on complete flowers. S. curvicornis spent less time on each flower when either pollen or nectar were removed, while L. malachurum had lower handling times when only pollen was absent. This supports the hypothesis of dietary specialization between the two species, with L. malachurum only collecting pollen from C. arvensis while S. curvicornis collects both pollen and nectar. Both species show unique foraging behaviors on C. arvensis; L. malachurum circles the inflorescence while S. curvicornis circles and simultaneously taps the inflorescence. Together with temporal niche separation in parallel studies by our group, these two species appear to effectively partition the C. arvensis resource.
