Effect of temperature on development and survival of immature stages of Bactrocera invadens (Diptera: Tephritidae)

The development and survival of immature stages of Bactrocera invadens Drew, Tsuruta and White (Dipt.: Tephritidae), a new invasive fruit fly pest in Africa, was studied in the laboratory at five constant temperatures of 15 degrees C, 20 degrees C, 25 degrees C, 30 degrees C and 35 degrees C and photoperiod of L12:D12. The developmental time of eggs was 5.71 days at 15 degrees C, decreasing to 1.24 days at 35 degrees C. Larval development periods decreased from 35.95 days at 15 degrees C to 6.64 days at 35 degrees C. Pupal development at 15 degrees C took 34.08 days while no adults emerged at 35 degrees C, this being the most lethal temperature. The longest total development period occurred at 15 degrees C (75.74 days) and was shortest at 30 degrees C (17.76 days). The linear model provided a reliable fit of development rates vs. temperature for the immature stages. Lower developmental thresholds that were estimated from linear regression equations for the egg, larva and pupal stages were 8.8, 9.4 and 8.7, respectively. Total degree-day (DD) accumulation was estimated at 376 DD for development from egg to adult emergence. The highest adult survival given as the mean of emergence from a cohort of 50 eggs occurred at 20-30 degrees C. At the egg stage, survivorship was highest at 20-30 degrees C and at the larva and pupa stages, it was at 25 degrees C. The practical implication of the findings is discussed in relation to mass rearing of B. invadens and understanding its biology and ecology.