Meeting Abstract

38.5  Jan. 5  Why do Africanized honey bees have higher metabolic capacities than Europeans? GRAYSON, Dina L.*; HARRISON, Jon F.; FEWELL, Jennifer H.; Arizona State University Dina.Grayson@asu.edu

Africanized honey bees (AHB, Apis mellifera scutellata) are a highly successful invasive species that has spread throughout the neotropics by out-competing, hybridizing with, and replacing existing European honey bees (EHB mainly Apis mellifera mellifera). It has been hypothesized that one mechanism contributing to their success is higher metabolic capacities leading to increased foraging, or dispersal. Although metabolic capacity has consistently been higher in foraging AHB than EHB, the link between metabolic capacity and any advantageous behaviors has remained unclear. Additionally, many hypotheses regarding the proximate causes of metabolic capacity differences, such as that higher metabolic capacities in AHB are the result of smaller body size, have never been conclusively tested. I tested three hypotheses that could explain why AHB have higher metabolic capacities than EHB. First, I showed that differences in larval rearing environment could not explain higher adult metabolic capacity in AHB by rearing AHB and EHB in shared and independent environments. Second, I showed that differences in body size could not explain differences in metabolic capacity by comparing AHB and EHB of similar sizes. Third, I showed that foraging load mass was not affected by metabolic capacity by evaluating unloaded metabolic capacity and load mass on the same individual bees. Overall, our results support the idea of a genetic basis for metabolic capacity in honey bees that can not be explained by differences in body mass or by selection on AHB to carry larger loads. Supported by NSF IBN 093410 to JHF, JFH, & GJH.