Individual variation in male pheromone production inXylocopa sonorinacorrelates with size and gland color

Abstract

Sex pheromones are species-specific chemical signals that facilitate the location, identification, and selection of mating partners. These pheromones can vary between individuals, and act as signals of mate quality. Here, we investigate the variation of male pheromones in the mesosomal glands of the large carpenter beeXylocopa sonorina, within a Northern California population. We tested the hypothesis that morphological traits are correlated with the observed variation in chemical blend composition of these bees. We also conducted behavioral assays to test whether these male pheromones act as long-range attractants to conspecifics. We found that larger males with darker mesosomal glands, an indicator of sexual maturity, have a higher pheromone amount in their glands. Our analysis also shows initial evidence that this pheromone blend serves as a long-range attractant to both males and females. We show that both male body size and sexual maturation are important factors influencing pheromone abundance, and that this 3-component pheromone blend acts as a long-range attractant. We hypothesize that females are more likely to mate with males releasing more pheromone, either due to increased ability to detect the blend or through female preference for pheromone abundance.