Effect of Wolbachia Infection and Adult Food on the Sexual Signaling of Males of the Mediterranean Fruit Fly Ceratitis capitata

Simple Summary The Mediterranean fruit fly (medfly) can infest many plant species and survive in different climatic conditions, thus leading to its invasion in new geographical regions and causing great economic losses in fruit production. Insecticides have been the major approach for the suppression of medfly populations for decades. However, concerns regarding insecticide impact on the environment led to the development of environmentally friendly techniques that rely on field releases of sterile males that produce no viable offspring when mated with wild females. One method of male sterilization is their infection with bacteria such as Wolbachia that induce sterility in infected males when crossed with uninfected wild females. The released sterile males should be competitive with wild males for mating with wild females. Therefore, it is important to evaluate the effect of Wolbachia on traits that determine male mating success, such as sexual pheromone signaling, and assess potential ways to improve mating success (i.e., enrichment of male diet with protein). In this study, we demonstrate that Wolbachia infection decreases sexual signaling frequency, but protein-enriched diets cannot counteract this negative effect. Our results contribute to the assessment of Wolbachia infection as an additional tool for population suppression of insect pests. Sexual signaling is a fundamental component of sexual behavior of Ceratitis capitata that highly determines males' mating success. Nutritional status and age are dominant factors known to affect males' signaling performance and define the female decision to accept a male as a sexual partner. Wolbachia pipientis, a widespread endosymbiotic bacterium of insects and other arthropods, exerts several biological effects on its hosts. However, the effects of Wolbachia infection on the sexual behavior of medfly and the interaction between Wolbachia infection and adult food remain unexplored. This study was conducted to determine the effects of Wolbachia on sexual signaling of protein-fed and protein-deprived males. Our findings demonstrate that: (a) Wolbachia infection reduced male sexual signaling rates in both food regimes; (b) the negative effect of Wolbachia infection was more pronounced on protein-fed than protein-deprived males, and it was higher at younger ages, indicating that the bacterium regulates male sexual maturity; (c) Wolbachia infection alters the daily pattern of sexual signaling; and (d) protein deprivation bears significant descent on sexual signaling frequency of the uninfected males, whereas no difference was observed for the Wolbachia-infected males. The impact of our findings on the implementation of Incompatible Insect Technique (IIT) or the combined SIT/IIT towards controlling insect pests is discussed.