Drosophila suzukii (Matsumura) is a species native to Western Asia that is able to pierce intact fruit during egg laying, causing it to be considered a fruit crop pest in many countries. Drosophila suzukii have a rapid expansion worldwide; occurrences were recorded in North America and Europe in 2008, and South America in 2013. Due to this rapid expansion, we modeled the potential distribution of this species using the Maximum Entropy Modeling (MaxEnt) algorithm and the Genetic Algorithm for Ruleset Production (GARP) using 407 sites with known occurrences worldwide and 11 predictor variables. After 1000 replicates, the value of the average area under the curve (AUC) of the model predictions with 1000 replicates was 0.97 for MaxEnt and 0.87 for GARP, indicating that both models had optimal performances. The environmental variables that most influenced the prediction of the MaxEnt model were the annual mean temperature, the maximum temperature of the warmest month, the mean temperature of the coldest quarter and the annual precipitation. The models indicated high environmental suitability, mainly in temperate and subtropical areas in the continents of Asia, Europe and North and South America, where the species has already been recorded. The potential for further invasions of the African and Australian continents is predicted due to the environmental suitability of these areas for this species.
Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae) is a widely distributed pest of soft-skinned and stone fruits that is controlled mainly with pesticides. An alternative to the chemical control is the sterile insect technique (SIT), an ecologically friendly method of pest management that could be used against D. suzukii. The objective of the present study was to evaluate the effects of gamma radiation on reproductive sterility, ovarian morphometry, and quality parameters of D. suzukii. Full female sterility was achieved at 75 Gy, while an adequate level of male sterility (99.67%) was obtained at 200 Gy. The ovarian size showed an exponential decay in function of irradiation dose increase. There was no significant influence of irradiation dose on the quality parameters evaluated. Our data suggest that gamma radiation can be recommended to be used in an SIT program for D. suzukii.
Female remating is a widespread behaviour, reported in several insect species. This behaviour can affect the efficiency of sterile insect technique (SIT); however, little is known about the postcopulatory behaviour of some pest species considered as candidates to be controlled by this technique, such as Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae). In this study, we investigated the effects of male and female sterilization on mating and remating behaviour of D. suzukii. First, we tested the occurrence of multiple mating in different combinations between sterile and fertile males and females. Then, we tested the effects of male and female sterility on female propensity to mate and remate. We found an overall low remating rate by D. suzukii females. Male sterility did not influence mating and remating likelihood; however, copula duration of sterile males was shorter compared to fertile males. On the other hand, sterile females were less likely to mate. Our findings encourage further research regarding the use of SIT to control D. suzukii.
Spotted-wing Drosophila, Drosophila suzukii (Matsumura, 1931), is an economic pest of thin-skinned fruit crops. Its control has commonly been carried out through chemical methods. However, given the need to develop safer and environmentally friendly management alternatives, the pupal endoparasitoid Trichopria anastrephae Lima stands out as a potential biological control agent. However, the lack of information on the mass rearing of this parasitoid limits its use. Thus, the objective of our study was to provide information that is useful for rearing T. anastrephae using D. suzukii as a host. The effects of pupal age, exposure time, and pupal density on the parasitism rate were examined, as was the effect of honey provision for extending adult parasitoid longevity. Exposing 15 12-h-old pupae per female for 24 h resulted in higher parasitism rates and a greater number of emerged parasitoids. Males and females of T. anastrephae fed with pure honey (100%) or honey diluted to 50% in water lived longer compared to those fed 10% honey, no food, or only water.
The pupal parasitoid Trichopria anastrephae Lima (Hymenoptera: Diapriidae) shows potential to control Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), and understanding the behavior of this parasitoid in challenging environments is important to obtain a higher efficiency in mass rearing and in biological control programs. This study aimed to verify the effects of extrinsic intraspecific competition and the absence of host on the parasitism of T. anastrephae in D. suzukii pupae. Therefore, to evaluate the parasitism of T. anastrephae under intraspecific competition, groups of 20 pupae (24 h old) of D. suzukii were offered for different densities of parasitoids (1, 3, 5, or 10 couples) during a 7-day period. Whereas to evaluate the effects of host deprivation on parasitism of T. anastrephae, we tested different treatments: T1-no deprivation, T2-complete deprivation, T3-deprivation every other day, T4-deprivation for 3 days, and T5-deprivation for 7 days. The increase of density of parasitoids resulted in an increase of oviposition scars on pupae and a longer biological cycle, suggesting the occurrence of superparasitism. Increased density also resulted in a higher percentage of attacked pupae, but did not affect parasitoids emergence nor sex ratio. Host deprivation affected number of parasitized pupae, number and sex ratio of offspring, and the longevity of females. Based on our findings, competition among females do not impair offspring viability, and host deprivation for a period up to 7 days do not influence parasitism capacity, indicating that it can be used as a pre-release strategy.
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