COMPARATIVE DEMOGRAPHY OF 2 CUCURBIT-ATTACKING FRUIT-FLIES, BACTROCERA-TAU AND B-CUCURBITAE (DIPTERA, TEPHRITIDAE)

Bactrocera tau (Walker) and Bactrocera cucurbitae (Coquillett) have si milar geographic distributions, host ranges, and damage levels in Chin a. The species were similar in duration of immature stages, preoviposi tion periods, and mean generation time, but differed in survivorship o f their immature stages and adults, net reproductive rate, and schedul e of egg production. Net reproductive rate was 58.8 and 72.9 for B. ta u and B. cucurbitae, respectively. Egg production peaked at an earlier age for B. tau, and B. cucurbitae lacked a clear peak of egg producti on. B. tau stopped laying eggs at an earlier age than B. cucurbitae. T he population growth rates of these two species are similar.