Variation in and responses to brood pheromone of the honey bee (Apis mellifera L.)

Brood pheromone, a blend of 10 fatty acid esters extractable from the surface of larvae, is an important releaser and primer pheromone of the honey bee. Interestingly, brood pheromone (BP) mediated behaviors associated with greater pollen foraging by Africanized bees are not dependant on the racial source of larval extracts. Increased Africanized worker ovarian follicle development is also not differentially inhibited by the racial source of larval extracts. This study compared fatty acid ester profiles among 8 colonies of Africanized and 6 colonies of European honey bees. Africanized larval extract was comprised of significantly greater proportions of methyl oleate, ethyl linolenate, and methyl linolenate than European larval extract. Discriminant analysis scores for methyl oleate, methyl stearate, and ethyl linoleate correctly categorized by race 85% of the 78 samples analyzed. Significant differences in methyl linolenate, combined with methyl oleate and methyl stearate suggested that the brood pheromone blend extractable from Africanized larvae may be an adaptation to the greater reproductive capacity of Africanized honey bees. Foraging responses to synthetic blends of Africanized and European BP by Africanized and European colonies will also be reported.