Thermal Development, Mortality, and Fertility of an Apulian Strain of Drosophila suzukii at Different Temperatures

This study explored the thermal response of <i>Drosophila suzukii</i>, an injurious insect pest present in many countries worldwide, at different controlled conditions. This species is responsible for several economic losses in soft fruit cultivations, develops on ripening fruits, and has the capability to quickly adapt to new territories and climates, closing multiple generations per year. Given its high invasive potential and the increasing need for low-impact control strategies, an in-depth exploration of the biology of this species and of the stage thermal response is fundamental. Specimens of an Italian strain from Apulia were reared in growth chambers at different constant temperatures (6, 9, 13, 18, 20, 24, 25, 26, 27, 28, 29, 31, 32 and 33 °C). The life cycle of each specimen was individually tracked from the egg to the death of the adults, considering the larval stages distinction as well. Besides development and mortality, egg production over temperature has been recorded. The dataset was first analysed according to life tables studies; then, we also estimated the biological parameters of the most common equations describing development, mortality, and fertility involved in physiologically-based model applications. The results confirmed and extended the information on the thermal response already present in the literature, but with reference to a population adapted to warmer climates. The species successfully developed from egg to adult at 13-29 °C, while between 6-9 and 29-33 °C the development was limited to L2/L3 stages. Optimal temperatures are around 26-28 °C, depending on the life stage. This study provides one of the complete overviews of the thermal response of <i>D. suzukii</i>, which is available in the current literature, and opens the door to more accurate modelling frameworks.