INCIPIENT POSTCOPULATORY ISOLATION AND MORPHOLOGICAL DIVERGENCE IN THE MELON FLY, BACTROCERA-CUCURBITAE

Post-copulatory isolation and the difference in morphological traits b etween populations of the melon fly, Bactrocera (Dacus) cucurbitae on Okinawa and Isigaki Islands in the Ryukyu Archipelago, which shared th e common ancestor in 1929 or later, were studied. The hatchabilities o f eggs from inter-population crosses were lower than those from intra- population crosses. Of four morphological traits studied, two measures of wing length and width between eyes of females in the Okinawa popul ation were larger than those of the Isigaki population. Measures of wi ng length and midleg length of males in the Okinawa population were la rger than those of the Isigaki population. The degrees of sexual dimor phism in two measures of wing length and width between eyes in Okinawa population were larger than in the Isigaki population. There were dif ferences between the populations in allometry of several pairs of the morphological traits.