ABILITY OF GENETIC SEXING STRAIN MALE MELON FLIES (DIPTERA: TEPHRITIDAE) TO SUPPRESS WILD FEMALE REMATING: IMPLICATIONS FOR SIT

For successful application of the sterile insect technique (SIT), wild female insects should not be more receptive to remating after mating with a mass-reared sterile male than after to mating with a wild fertile male. The remating frequencies of melon fly Bactrocera cucurbitae Coquillett (Diptera: Tephritidae) females were assessed in field cages with male melon flies from: (1) a male-only genetic sexing strain (GSS) originating from Hawaii, (2) a bisexual (male and female) laboratory strain originating from Mauritius, and (3) a wild colony (less than 5 generations in culture) also from Mauritius. One objective of this study was to assess the ability of GSS males to suppress the remating of females of different strains as compared to the ability of males of bisexual strains to do so. A second objective was to assess the effect of mass-rearing and irradiation on the ability of GSS males to suppress female remating. The males of the GSS achieved significantly fewer matings with female flies from the laboratory adapted and wild strains during the first mating than males of these bisexual strains. However, GSS males were equally able to diminish the females' remating frequency as laboratory and wild males. Remating frequencies of GSS females were significantly higher than those of females of the bisexual strains. Our results, however, indicate that laboratory rearing had no effect on the remating frequency of melon fly females. Thus the higher remating frequency of GSS females seemed to be a strain specific characteristic. Furthermore, irradiation of male melon fly pupae with 70 Gy had no effect on female remating frequencies, and the abilities of irradiated GSS and wild males to suppress wild female remating were similar. These results are discussed in the context of the feasibility of incorporating the use of irradiated GSS males as the SIT component of area-wide pest management programs against B. cucurbitae.