Thermal effects on the development of Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae) and model validation

The melon fruit fly Zeugodacus cucurbitae (Coquillett) is a major polyphagous insect pest with a worldwide distribution. The effects of temperature on the development of Z. cucurbitae were investigated at eight constant temperatures. Freshly deposited egg and emerged larvae of Z. cucurbitae were used for experiment and the development of eggs, larvae and pupae was examined daily. With the exception of the lowest temperature (12.0 °C), Z. cucurbitae developed successfully from the egg stage to the adult stage at all the assessed temperatures. The lower developmental thresholds and thermal constants of each life stage were determined using linear regression. The lower and higher temperature thresholds were estimated using the Lobry–Rosso–Flandrois (LRF) and Sharpe–Schoolfield–Ikemoto (SSI) models. The lower developmental threshold and thermal constant from egg to adult emergence were 10.7 °C and 218.7 degree-days, respectively. The intrinsic optimum temperatures of the egg, larval, pupal and egg to pupal stages were 30.3, 24.4, 24.5, and 25.7 °C, respectively. Using the SSI model, we determined a temperature range of 23.1 °C (13.3–36.4 °C) for the total immature stage of Z. cucurbitae from lower and higher temperature threshold. The cumulative 50% adult emergence estimated using the SSI model was approximately 1 day later than that observed from Momordica charantia L. , which was used for validating the distribution of adult Z. cucurbitae emergence. We elucidated the thermal performance of Z. cucurbitae using linear and non-linear models, and these models will contribute to the development of an effective management program for Z. cucurbitae .