Reproductive potential and population increase of Drosophila suzukii at constant temperatures

The invasive species Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) represents a serious problem in Europe and America for the production of a wide variety of small fruits. Originally endemic to Southeast Asia, it is able to attack healthy ripening fruit where females lay eggs with its serrated ovipositor. The main factor determining population increase of this fly is temperature. Different studies have focused on the effect of this factor on reproduction of American and Asian populations. However, no comprehensive study has been conducted to date on European populations. The effect of eight constant temperatures (13, 16, 19, 22, 25, 27, 29 and 30 degrees C) on reproduction, adult survival and life table parameters of a Spanish population was modelled. The highest fecundity (341.3 eggs/female) and daily fecundity (11.6 eggs/female/day) were obtained at 22 degrees C. Egg laying decreased below and above this temperature until the lowest values were obtained at extreme temperatures. Conversely, decreasing values of oviposition period and adult longevity were registered for increasing temperatures. A non-linear Briere model predicted at 9.8 and 30.6 degrees C the lower and upper thresholds for population increase, determining a wider range than that previously reported for this species. The predicted optimum temperature for population increase was 25.3 degrees C. The intrinsic rates of population increase obtained are among the highest described for this fly. These results could be an additional tool to be included into demographic models to predict population dynamics of this pest.