Meeting Abstract

55.11  Tuesday, Jan. 6  Foraging Patterns of Bees in Response to Nectar Availability in Populations of the Invasive Thistle Species Centaurea solstitialis L. in Native (Greece) and Non-Native (USA) Island Ecosystems BARTHELL, J.F.*; CLEMENT, M.L.; WELLS, H.; CROCKER, K.C.; BECKER, E.C.; LEAVITT, K.D.; MCCALL, B.T.; MILLS-NOVOA, M.; WALKER, C.M.; PETANIDOU, T.; Univ. Central Oklahoma; Univ. Central Oklahoma; Univ. of Tulsa; Cornell Univ.; Univ. Central Oklahoma; Portland State University; Oklahoma State Univ.; Lewis and Clark College; Oklahoma State Univ.; Univ. of the Aegean, Lesvos jbarthell@ucok.edu

We compared nectar flow and standing crop levels among populations of the highly invasive plant species yellow star-thistle, Centaurea solstitialis L., to test the hypothesis that nectar levels influence the guild composition and foraging patterns of bees. Specifically, we predicted that the invasive, eusocial honey bee (Apis mellifera L.) responds differently to nectar availability than do the predominantly native, non-social bee species. The work was conducted at two island ecosystem locales, including the Northeast Aegean island of Lesvos (Greece) and Santa Cruz Island (California, USA) where studies of honey bees have been conducted in the past. At both locales, we found that larger bodied and/or social bee species were associated with those plots with higher average nectar standing crop levels. Indeed, on Lesvos, we found that honey bees were more abundant on the nearby high nectar-secreting plant species Vitex agnus-castus L. These patterns are consistent with other data and at least one model described in the literature. Additionally, we report on levels of damage to flower heads by natural enemies (tephritid flies) and suggest how negative ecological interactions (e.g., phytophagy) may ultimately compromise the success of invasive plant species in newly invaded environments.