HOST-SPECIFIC DEMOGRAPHIC-STUDIES OF WILD BACTROCERA-TAU (WALKER) (DIPTERA, TEPHRITIDAE)

Developmental time and survival rates of preadult stages and adult sur vival and fecundity of Bactrocera tau (Walker) were examined when rear ed on six common hosts at 25-degrees-C. The durations of the egg and p upal stages were independent of host. The larval developmental time ra nged from 4.5 days, for those reared on cucumber, to 7.3 days, for tho se reared on eggplant. The survival rate of larvae ranged from 48%, wh en reared on bitter melon, to 77%, when reared on cucumber. Net reprod uctive rates (R(o)) were similar when the files were reared on bitter melon, papaya, and cucumber, and they were twice that of flies reared on eggplant. The generation time ranged from 59.1 days, for flies rear ed on pumpkin, to 40.7 days, for those reared on eggplant. The intrins ic rate of increase ranged from 0.087, for the flies reared on waterme lon, to 0.123, for those reared on cucumber. The data indicate that B. tau is capable of reaching high population densities quickly on a num ber of hosts, and that this fly poses a significant threat to agricult ure in California.