Phenology of Fopius arisanus

Fopius arisanus (Sonan), a koinobiont solitary egg-pupal endoparasitoid of numerous tephritid fruit fly specie, was recently introduced into Africa for the control of the Oriental fruit fly, Bactrocera dorsalis (Hendel). In this study, life-table data of F. arisanus were generated under laboratory conditions at six constant temperatures (15, 20, 25, 30, 28 and 35 °C; 75% RH, L12:D12 photoperiod) on Bactrocera dorsalis. Several non-linear functions were fitted to model species development, mortality, longevity and oviposition using the Insect Life Cycle Modeling software. The established phenology models were stochastically simulated at fluctuating temperatures to estimate the life table parameters. F. arisanus completed development from egg to adult at all the temperatures tested except at 35 °C. Mean developmental time from egg to adult was inversely proportional to the temperature. The minimum temperature threshold (Tmin) from egg to adult was 8.15 °C, while the maximum temperature threshold (Tmax) was estimated at 34.2 °C. The optimal temperature for immature stages survival was predicted for 20 to 30 °C. The optimum fecundity estimated was 251 eggs/female at 22 °C. Following the stochastic simulations, the Humid Forest with Bimodal Rainfall of Cameroon presented suitable thermal conditions for potential population growth of F. arisanus. The present study shows the importance of temperature on the demographic parameters of F. arisanus. Effect of the difference in thermal requirements between B. dorsalis and F. arisanus on biological control under climate change scenarios is discussed.