Natural selection, rather than sexual selection, plays a dominant role in the formation of body coloration in <i>Drosophila suzukii</i>

Abstract Drosophila suzukii is a globally distributed pest, and its body colour exhibits notable plasticity. Given the important roles of natural and sexual selection in the formation of insect traits, we deduced that both natural and sexual selection play key roles in the development of body coloration in D. suzukii. We measured the dorsal abdominal melanization, chill coma recovery time, and mating success in D. suzukii, examining the roles of natural and sexual selection in shaping body colour traits. The results showed that the melanization rate of D. suzukii reared at 15°C (male, 0.707 ± 0.012; female, 0.618 ± 0.019) was significantly higher than that of individuals reared at 25°C (male, 0.559 ± 0.011; female, 0.314 ± 0.010); the chill coma recovery time of D. suzukii reared at 15°C was significantly shorter than that of individuals reared at 25°C. Our study elucidates quantitatively the relative contributions of natural and sexual selection to the formation of the plastic body colour phenotype in D. suzukii. Natural and sexual selection accounted for 89.02% and 10.92% of the total selection differential, respectively. Thus, natural selection predominates in shaping body coloration in D. suzukii.