A High‐Resolution Method Using Individual Females to Assess the Competitiveness of Sterile Drosophila suzukii Males Under Semi‐Controlled Conditions

The sterile insect technique (SIT) is a species‐specific method used to manage insect pest populations. It relies on the repeated releases of sterile insects, their mating with wild females and the following reduction of egg viability. The SIT efficacy depends on the sexual performance of the released insects, which varies with insects' intrinsic properties as well as production and irradiation conditions. Identifying and addressing insect quality issues is therefore paramount. In this study, we focused on the development and validation of a novel method for assessing the sexual competitiveness of sterile mass‐reared males of the fruit pest Drosophila suzukii Matsumura, 1931 (Diptera). This method is based on sterile males competing with fertile males in mesh cages containing fertile females under semi‐controlled conditions. After 24 h, females were isolated individually and the viability of their progeny assessed. We illustrate the use of this procedure by comparing the competitiveness of different D. suzukii populations, from the laboratory, from the field and after refreshing the genetic diversity of a laboratory strain. Our assay further showed that sterile mass‐reared males from two different colonies were equally sexually competitive as wild type males under semi‐controlled conditions. These results were also supported by a mating test. The procedure presented here may contribute to the development of D. suzukii SIT by facilitating the assessment of insect quality.