Drosophila suzukii (Diptera: Drosophilidae) Population Dynamics and Infestation in a Raspberry Orchard of Loukkos Area, Morocco.

Raspberries (Rosales: Rosaceae) are considered to be one of most important crops in northwestern Morocco. However, this sector is seriously affected by the attack of Drosophila suzukii, which impairs the production and the export. Furthermore, the eco-ethology and population dynamics of D. suzukii under Moroccan conditions are still poorly understood. In Larache region, we monitored the population dynamics of D. suzukii adults using 4 traps baited with mashed ripe banana mixed with yeast, and reported the infestation levels during spring of 2022, 2023, and 2024 on raspberry cultivar Rubus idaeus var. Yazmin. Our results indicate that a maximum of 14, 20, and 28 D. suzukii adults per trap were caught weekly at the end of April 2022, in the middle of March 2023, and in the middle of April 2024, respectively. Furthermore, three peaks of D. suzukii adult flies were observed each year, whereas a total of six generations were predicted according to the accumulated degree-days. The male sex ratio of trapped D. suzukii was 1:0.32, 1:0.38, and 1:0.42 in 2022, 2023, and 2024, respectively. Raspberry fruit infestation reached a maximum of 76%, 75%, and 64% at the beginning of May 2022, middle of April 2023, and end of April 2024, respectively. Under the climate change scenario, knowledge of the eco-ethology of this insect and its population dynamics is essential for developing an IPM control strategy in Morocco, and further studies are ongoing to establish a biological and reasoned chemical approach based on degree-days.