Abstract
The courtship calling frequency of males and the time of mating during the day were compared between an Okinawa mass-reared strain and a Taiwan wild strain of the melon fly, Bactrocera cucurbitae (Coquillett). The mass-reared strain was maintained for about 150 generations under artificial rearing conditions and was concurrently used for the sterile insect technique (SIT) in Okinawa. The call frequency of males was significantly lower in the Okinawa mass-reared strain than in the Taiwan wild strain, and the mating time of mass-reared males was significantly later in the day than that of Taiwan wild-strain males. Moreover, the mating competitiveness of the Okinawa mass-reared strain was lower than the Taiwan wild strain in mate-choice tests. These results suggest that improvement in the mating competitiveness of mass-reared melon flies or the introduction of a new strain from a foreign country is urgently needed for the SIT program to eradicate the melon fly population in case of reinvasion in Japan.
