Remating inhibition in Queensland fruit flies - Does sperm storage matter?

Ability to prevent their mates from accepting subsequent suitors as mates is an important determinant of male fitness in many animals. We investigated whether male Queensland fruit fly ability to have many sperm stored by their mates influences probability that their mates will remate over the course of the following week. We relied on both natural variation and also used irradiation to disrupt spermatogenesis in males so that they transferred few or no sperm. There was no evidence of relation between number of sperm stored by females from their first non-irradiated mate and probability of remating. Also, irradiated males were as successful as non-irradiated males at inducing sexual resistance in their mates. However, sperm tended to be stored highly asymmetrically between the female's two spermathecae, and female remating tendency did vary with asymmetrically between the female's two spermathecae, and female remating tendency did vary with asymmetry of storage. We discuss some hypotheses related to this relationship between sperm storage patterns and subsequent female mating behaviour.