Comparative Demography of Three Hawaiian Fruit Flies (Diptera:Tephritidae) at Alternating Temperatures
ROGER I. VARGAS, WILLIAM A. WALSH, DALE KANEHISA, JOHN D. STARK, AND
Reproductive and population parameters of melon ßies, Bactrocera cucurbitae Coquillett, oriental fruit ßies, B. dorsalis Hendel, and Mediterranean fruit ßies, Ceratitis capitata (Wiedemann), were measured in environmental chambers maintained at temperatures of (maximum: minimum) 24:13, 24:24, 29:18, and 35:24 6 18C. Alternating temperature regimes more realistically approached the variation found in nature and produced higher parameters than an optimal constant temperature (248C). Intra- and interspeciÞc comparisons were done with 4 separate generations of wild fruit ßies reared on a common natural host. All species attained their highest intrinsic rates of population increase at 29:18 or 35:248C; C. capitata exhibited the highest intrinsic rates of increase at all temperature regimes. All species attained maximum net reproductive rates at 29:188C, in the order C. capitata.B. dorsalis.B. cucurbitae. The 35:248C regime caused reductions in net reproductive rates of all species, with B. dorsalis affected most strongly. Male longevity was greater than that of females for all species in all temperature regimes. Two distinctly different life history patterns were evident: (1) early reproduction, short life span, and a high intrinsic rate of increase (C. capitata), and (2) later onset of reproduction, longer life span, and a lower intrinsic rate of increase (B. cucurbitae).