Sperm precedence pattern and the effect of irradiation on male mating competition in the oriental fruit fly, Bactrocera dorsalis

Abstract

The sterile insect technique (SIT) is a feasible control strategy for the oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) attacking diverse fruits. Our understanding for the sperm precedence pattern and mating competition of the irradiated males of B. dorsalis relative to the unirradiated ones is important for SIT program. Here we employed the sterile male technique to determine sperm precedence pattern and compare their mating competition between the irradiated and unirradiated males B. dorsalis. Our results indicated that the unirradiated males were significantly more competitive at mating over the irradiated ones. In twice-mated females the mating order between the irradiated and the unirradiated males had little effect on the number of eggs laid, but the proportion of the hatched eggs was significantly lower for females that mated first with an irradiated male than the females that mated first with a unirradiated male. There were significant differences in fecundity and fertility when females paired with various ratios of the irradiated males to the unirradiated ones. With the increase of the ratios of the irradiated males to the unirradiated ones, female fecundity and fertility gradually declined. It seems likely that SIT (sterile male technique) is promising for the control of the fruit fly B. dorsalis.