THE EFFECT OF GENOTYPE ON RESPONSE THRESHOLDS TO SUCROSE AND FORAGINGBEHAVIOR OF HONEY-BEES (APIS-MELLIFERA L.)

Honey bee foragers were tested for their proboscis extension response (PER) to water and varying solutions of sucrose. Returning pollen and nectar foragers were collected at the entrance of a colony and were as sayed in the laboratory. Pollen foragers had a significantly higher pr obability of responding to water and to lower concentrations of sucros e. Bees derived from artificially selected high- and low-pollen-hoardi ng strains were also tested using the proboscis extension assay. Retur ning foragers were captured and tested for PERs to 30% sucrose. Result s demonstrated a genotypic effect on PERs of returning foragers. The P ERs of departing high- and low-strain foragers were consistent with th ose of returning foragers. The PERs were related to nectar and water r eward perception of foragers. High strain bees were more likely to ret urn with loads of water and lower concentrations of sucrose than forag ers from the low pollen strain. Low-strain bees were more likely to re turn empty. We identified a previously mapped genomic region that cont ains a variable quantitative trait locus that appears to influence suc rose response thresholds. These studies demonstrate a gene-brain-behav ior pathway that can be altered as a consequence of colony-level selec tion for quantities of stored food.