Thermal effects on the development of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) and model validation in Taiwan

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a major polyphagous insect pest with a worldwide distribution. The effects of temperature on stage-specific development in B. dorsalis were investigated at eight constant temperatures (13.0 A degrees C, 14.4 A degrees C, 16.2 A degrees C, 19.5 A degrees C, 23.8 A degrees C, 27.7 A degrees C, 31.8 A degrees C and 34.8 A degrees C). B. dorsalis developed successfully from the egg stage to the adult stage at all the tested temperatures, except at the lowest temperatures (13.0 A degrees C and 14.4 A degrees C). Stage-specific lower developmental thresholds and thermal constants were determined using linear regression. The lower and higher temperature threshold (TL and TH, respectively) were estimated using the Sharpe-Schoolfield-Ikemoto model. The lower developmental threshold and thermal constant from egg to adult emergence were 9.8 A degrees C and 325.5 degree-days, respectively. The intrinsic optimum temperatures of the egg, larval, pupal and egg to pupal stage were 20.7 A degrees C, 21.8 A degrees C, 21.1 A degrees C, and 22.4 A degrees C, respectively. The temperature range of the B. dorsalis total immature stage from TL to TH was 20.4 A degrees C (13.8 A degrees C - 34.2 A degrees C). The stage-specific developmental completion of B. dorsalis was determined using a two-parameter Weibull function. The daily adult emergence frequency of B. dorsalis was estimated in relation to adult age and temperature using non-linear developmental rate functions and the Weibull function. The date of cumulative 50% adult emergence estimated using non-linear functions was approximately one day earlier than the experimentally observed date. Thermal performance was compared among B. dorsalis populations from different locations.