Biotechnological Control Strategies for Managing Drosophila suzukii

Abstract

Drosophila suzukii (D. suzukii) is an invasive pest native to East Asia that has established itself across much of the world. Unlike most Drosophila species, which prefer decaying organic material for reproduction, D. suzukii targets fresh and ripening fruits, causing significant agricultural damage. Larval feeding and subsequent secondary infections can result in complete crop loss. Current control strategies rely heavily on chemical insecticides, which pose environmental risks and affect non-target organisms. This underscores the urgent need for safer and more sustainable alternatives. This dissertation investigates three biotechnological control strategies against D. suzukii. The first approach enhances the Sterile Insect Technique (SIT), a method that reduces pest populations through the release of sterilized males. Three key advancements are presented: (1) development of a non-destructive sexing method based on pupal weight differences, (2) identification of optimal X-ray sterilization conditions (90 kV/40 Gy), and (3) implementation of a temperature-based sterilization technique utilizing the natural thermosensitivity of D. suzukii males. The second strategy focuses on characterizing La Jolla virus (LJV), a candidate for virus-based biocontrol. The study examines natural transmission routes, including airborne, venereal, oral, and fecal, and investigates the virus’s pathology. LJV infection was shown to affect feeding behavior, nutrient absorption, fecundity, and egg-to-adult viability, offering insight into its potential as a biological control agent. The third approach explores RNA interference (RNAi) as a control tool in two contexts: enhancing SIT by generating sterile male-only populations through gene silencing, and deploying RNAi as a biopesticide by targeting essential genes. However, under the tested conditions, RNAi did not yield significant effects in either application. Collectively, the findings provide valuable contributions to the development of targeted, environmentally friendly control methods for D. suzukii, highlighting both promising advances and existing limitations in the field of biological pest management.