UC San Diego

Nest defense in the honey bee (Apis mellifera) is a complex collective behavior modulated by various interacting social, environmental, and genetic factors. Scutellata-hybrid ("Africanized") honey bees are usually considered to be far more defensive than European honey bees which are therefore preferred for commercial and hobbyist beekeeping. In the most recent zone of scutellata hybridization, the southern USA, the degree to which this defensiveness differs among current strains, and the extent to which defensiveness varies across a season has not been measured. We quantified the levels of A. m. scutellata ancestry in colonies and conducted a seasonal assessment (May through November) of colony nest defensiveness in feral scutellata-hybrid and a popular lineage of European honey bee commonly used in managed environments (sold as A. mellifera ligustica) hives at two apiaries in Southern California. Standard measures of defensiveness were low in both scutellata-hybrid and European colonies during May. Defensiveness increased during the later months of the study in scutellata-hybrid colonies. Most measures of defensiveness did not increase in managed colonies. Defensiveness in the scutellata-hybrids appears lower than what has been previously documented in Brazil and Mexico, possibly due to their lower proportion of A. m. scutellata ancestry.