Project in brief

The invasive species Drosophila suzukii (Matsumura) has become particularly significant in recent years in European soft fruit crops, especially in Italy, where it causes severe damage to fruit production. Using its characteristic ovipositor, it is able to lay eggs in ripening fruits, reducing their marketability. Currently, the management of the species is based mainly on the use of insecticides and biological control, through parasitoids. However, it is not clear how these two control methods interact with each other in terms of Integrated Pest Management (IPM) of the species.

This project focuses on studying the consequences of the development of insecticide-resistance to pyrethroids and spinosyns in D. suzukii.  The study will evaluate the potential impact of this phenomenon on the efficacy of biological control, with particular attention to the performance of the larval parasitoid Ganaspis kimorum. Since insecticide-resistant populations are not yet present in Europe, two resistant lines will be selected by exposing a D. suzukii susceptible population to insecticides in a controlled laboratory conditions. To evaluate and quantify possible fitness costs associated with the development of insecticide-resistance, these populations will be characterized by measuring life-history traits. Then, the resistant and susceptible lines will be exposed to the parasitoid to evaluate its efficacy as a biocontrol agent. Finally, the results will be validated by exposing a naturally occurring insecticide-resistant population of D. suzukii from California to G. kimorum. These experiments will clarify how the evolution of insecticide resistance could modify the ecological dynamics of D. suzukii and the success of biological control programs. The outcomes will provide useful guidelines for effectively integrating chemical and biological control methods for the management of D. suzukii. This will contribute to developing integrated and sustainable pest management strategies. Furthermore, the results will contribute to obtaining a generalizable model that could be applied to other host-parasitoid systems.

Project Objectives

• Obtain an insecticide-resistant population of D. suzukii, respectively, to pyrethroids and spinosyns, from a susceptible population.
• Evaluate fitness costs associated with the development of insecticide-resistance to selected insecticides.
• Analyze and compare the performance of the larval parasitoid G. kimorum on insecticide-resistant or susceptible host populations.
• Validate the results obtained by offering to the parasitoid G.kimorum a naturally occurring insecticide-resistant population of D. suzukii from California. 

Impact

The project offers the opportunity to characterize insecticide-resistant populations of D. suzukii and to estimate the efficacy of G. kimorum in controlling the species under the selective pressure of insecticides in agroecosystems. These results will inform the development and implementation of IPM strategies for this pest. If a negative effect of the development of insecticide-resistance in the host on the performance of the parasitoid is observed, the study would provide a basis for further research aimed at defining guidelines for the classes and methods of application of insecticides. This is particularly relevant to preserve the effectiveness of sustainable management approaches, such as biological control programs. 

Funding

Biotechnology and Biological Control Agency (BBCA)

Team

• Prof. Gianfranco Anfora
• Dr. Francesca Marini
• dott.ssa Barbati Giorgia
• Dr. Marco Valerio Rossi Stacconi