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Drosophila suzukii is a highly polyphagous pest species that can also attack grape. To prevent economic damage in vineyards, it is important to detect D. suzukii infestation early in order to protect grapes efficiently. Here, we firstly examined if peripheral zones adjacent to natural habitats and central zones within a vineyard differ in infestation levels, and, secondly, where within a grape cluster most eggs are laid. Among the eight infested vineyards studied, seven had higher D. suzukii infestation levels in peripheral zones adjacent to hedgerows, forests or gardens. Females laid 2.0‐fold more eggs on berries in the interior of grape clusters than on berries on the exterior of the cluster. Based on the finding that berries in the interior of grape clusters are more vulnerable, we developed a novel sampling method to estimate D. suzukii infestation level in vineyards more effectively. The so‐called 'whole cluster method' consists of a representative but random collection of five grape clusters per plot and a visual inspection of five berries each from the inner and outer part of a cluster totalling 50 checked berries per plot. We then compared our newly developed method to two established sampling methods to estimate D. suzukii infestations (i.e. 'single berry method' and 'cluster fragment method'), which rarely collect and inspect berries from the interior of clusters. In 87 comparisons conducted in 35 different plots, the 'whole cluster method' was the most sensitive sampling method as the calculated mean infestation rate was highest and it identified eggs earlier and in more samples than the other two methods. We therefore believe that the 'whole cluster method' is currently the most effective method to assess D. suzukii infestations in commercial vineyards. [ABSTRACT FROM AUTHOR]

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a widely distributed pest species of soft‐skinned fruits. Recent studies suggest the use of sterile insect technique (SIT) as a control method for this species; however, many factors can impact effectiveness of a SIT programme, including the environmental conditions. Environmental condition is critical at the time of the release and in the days afterwards, since it may impact sterile insects' survival and ability to mate. Thus, we verified the influence of temperature and relative humidity on mating and survival of fertile and sterile D. suzukii, when insects were food provided or deprived. Highest mating rates occurred when sterile or fertile flies provided with food were exposed to 25ºC or 81%–100% relative humidity, while temperatures of 10 and 35ºC and humidity below 60% impaired mating. Overall, mating rate among food‐deprived flies was low in all temperatures and humidity levels tested, but fertile insects were more prone to mate when compared to sterile flies. Survival was negatively influenced by high temperatures, low relative humidity and food deprivation. The information present in this study is useful to be considered for release of sterile D. suzukii. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of pest insect populations in relation to the presence of non‐crop habitats and infestation levels of adjacent crops is essential to develop sustainable pest management strategies. The invasive pest species Drosophila suzukii (Diptera: Drosophilidae) is able to utilize a broad range of host plants. In viticulture, scientific risk assessment for D. suzukii has only recently started and studies assessing the effects of field margins containing wild host plants on D. suzukii population dynamics and on infestation risks in adjacent vineyards are lacking. Thus, in a one‐year field study, the role of different field margins on fly abundance and crop infestation in adjacent vineyards of Vitis vinifera, variety "Pinot Noir," were investigated. Different monitoring methods were conducted to assess fly distribution, sex ratio and grape infestation in 14 vineyards adjacent to field margins containing either blackberry (BB) Rubus spp. or non‐host (NH) plants. Our results show that blackberries strongly enhanced D. suzukii abundance within field margin vegetation all year long, whereas fly abundance in vineyards adjacent to BB margins was just enhanced in some seasonal periods. Moreover, the influence of BB margins was limited by distance. However, high fly numbers in BB field margins did result in zero egg infestation of "Pinot Noir" berries. These results may have important implications for winegrowers to make efficient management decisions: regardless of high abundance of adult D. suzukii, only grape berry monitoring can assess the actual infestation risk and the potential need to take management action. [ABSTRACT FROM AUTHOR]

Abstract: In just a few years, the Asian fly Drosophila suzukii has invaded several continents and has become a very serious pest of many fruit crops worldwide. Current control methods rely on chemical insecticides or expensive and labour‐intensive cultural practices. Classical biological control through the introduction of Asian parasitoids that have co‐evolved with the pest may provide a sustainable solution on condition that they are sufficiently specific to avoid non‐target effects on local biodiversity. Here, we present the first study on the development of three larval parasitoids from China and Japan, the Braconidae Asobara japonica and the Figitidae Leptopilina japonica and Ganaspis sp., on D. suzukii. The Asian parasitoids were compared with Leptopilina heterotoma, a common parasitoid of several Drosophilidae worldwide. The three Asian species were successfully reared on D. suzukii larvae in both, blueberry and artificial diet, in contrast to L. heterotoma whose eggs and larvae were encapsulated by the host larvae. All parasitoids were able to oviposit one day after emergence. Asobara japonica laid as many eggs in larvae feeding in blueberry as in artificial diet, whereas L. heterotoma oviposited more in larvae on the artificial diet and the Asian Figitidae oviposited more in larvae feeding on blueberry. Ganaspis sp. laid very few eggs in larvae in the artificial diet, suggesting that it may be specialized in Drosophila species living in fresh fruits. These data will be used for the development of a host range testing to assess the suitability of Asian parasitoids as biological control agents in invaded regions. [ABSTRACT FROM AUTHOR]

Drosophila suzukii Matsumara (Diptera: Drosophilidae) is an invasive vinegar fly that infests ripe and ripening soft skinned fruits. In the south-eastern United States, blackberry ( Rubus spp.) crops are heavily impacted by D. suzukii, and current management tactics rely on the use of broad-spectrum insecticides targeted to adult populations. An improved understanding of D. suzukii biology and ecology are necessary to create sustainable management options. Knowledge of how D. suzukii interacts with resources will enable targeted management actions in the future. In this present study, we monitored larval infestation throughout the blackberry canopy and found that infestation was highest in the inner portion of the canopy and lower in more exposed locations. We also documented higher humidity within the cane canopy relative to the edge of the field. A difference in abiotic conditions may create within-crop microhabitats that D. suzukii is able to exploit. Future research will explore how to take advantage of these microhabitats in pest management programs. [ABSTRACT FROM AUTHOR]

Bioassays tested insecticidal activity of Erythritol from the nutritive sweetener, Truvia, and an insect growth regulator, Lufenuron, against life stages (eggs, larvae, pupae, adults) of Drosophila melanogaster (Meigen) and Drosophila suzukii (Matsumura), the spotted wing Drosophila ( SWD). These compounds were chosen for their demonstrated acute toxicity to adult and larval Drosophila and potential use on organic fruit farms. D. melanogaster fed on standard Drosophila diet media moistened with water containing known concentrations of Erythritol. Likewise, SWD consumed standard diet media as well as thawed host fruit (blackberries and blueberries) treated with solutions of Erythritol, Lufenuron or both. During the first bioassay, Erythritol at lower concentrations between 0 and 500 m m (~61 000 ppm) in water and mixed with instant diet media increased adult survival from ~80% to 97% for D. melanogaster and SWD. However, from aqueous concentrations ranging from 1750 (~414 000 ppm) to 2000 m m (~244 000 ppm), Erythritol killed 100% of adult Drosophila in culture vials. One hundred per cent mortality for SWD and D. melanogaster occurred at ≥0.5 m (~61 000 ppm) Erythritol added to diet media or topically applied to host fruit. In a second bioassay, 0.013-1.000 ppm of aqueous Lufenuron, a chitin synthase inhibitor, when added to dry diet media prevented 90-99% of SWD from reaching the pupal stage. In another assay, ~67% of SWD eggs or neonates (early first instars) died inside blackberries pre-treated with (dipped in) a soapy solution of 10 ppm Lufenuron. Pre-treating blackberry fruit with an Erythritol-Lufenuron mixture reduced SWD brood survival by 99%. Likewise, during our last fruit-based bioassay, 98% of eggs and neonates died inside blueberries similarly pre-treated. During the last experiment, Lufenuron in diet media also rendered adult females sterile. Sterility, however, dissipated over 7 days once females began feeding on a Lufenuron-free diet media. [ABSTRACT FROM AUTHOR]