Abstract
A new strain of the melon fly, Dacus cucurbitae COQUILLETT, was able to produce successive generations by mass rearing and its reproductive characteristics were studied in the mass rearing facility of Ishigaki, Okinawa, Japan, from 1978 to 1980.
Production of successive generations of the new strain consisted of three steps; 1) (0-3 generations from introduction) establishment of an initial stock, 2) (4-7 generations) selection to achieve high fecundity and 3) (8-9 generations) replacement of the old strain by the new strain. The target values of egg production (40ml per 50, 000 flies), percentage recovery of pupae from eggs (70 percent) and the percentage emergence of adults from pupae (90 percent) were attained in the 7th, 5th and 6th generations from introduction, respectively.
Reproductive characteristics such as the trend of oviposition, survivorship and accumlative mating occurrence under laboratory conditions were compared among wild, new and old strains, in a number of generations in the range of about 0-1, 13 and 60-61, respectively from introduction.
The great majority of adults of the new strain and the old one mated earlier and laid more eggs earlier as compared with those of the wild strain. The longevity of the new strain was higher than that of the old strain and much higher than that of the wild strain.
These results suggest that selection for high fecundity resulted in a change in other reproductive characters such as survivorship and mating occurrence.
