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Drosophila suzukii is widely studied because of its status as a global pest of berries and soft fruits. Environmental conditions and access to food resources impact the physiology and fitness of D. suzukii; these factors could also affect dispersal. Flight mills are a convenient tool for measuring and comparing the flight performance of insects. In this study, two experiments examined the effects of diet and humidity on D. suzukii flight performance using custom-built flight mills, and a third experiment compared the energy reserves of D. suzukii flown or not flown on flight mills. Over all flight assays, the median flight distance and duration were 27.16 m and 2.37 min, respectively, and the mean flight velocity was 0.18 m/s. The maximum flight distance and duration by an individual were 1.75 km and 2.35 h, respectively. Drosophila suzukii provisioned with blossoms, fruits, or standard laboratory diets flew farther distances and longer durations than starved flies. While starvation was associated with reduced flight performance, there were no observed differences between diet types. It remains unclear whether D. suzukii consistently use lipids, glycogen, sugar, or another energy source for flight because tethered individuals may not have flown enough to deplete energy reserves. Humidity did not affect flight performance of D. suzukii within a ~ 2 h test period. These data indicate that most D. suzukii are likely to remain within limited area (e.g., within a field) but that some individuals can disperse long distances (field to field spread).

Drosophila suzukii (Matsumura) is an economic pest of small fruits and cherries that attacks intact ripening fruits. Host susceptibility may be influenced by characteristics such as flesh firmness, penetration force of the skin, total soluble solids (TSS, also known as °Brix), and pH. Improved knowledge of factors affecting fruit susceptibility is needed for developing thresholds and risk prediction models for IPM. A combination of laboratory and field studies was conducted to develop prediction and potential management tools. First, a direct bioassay was used to calculate the probability of oviposition in a given fruit based on various characteristics as determined across laboratory and field trials in Oregon and North Carolina, US. When multiple characteristics were evaluated simultaneously, oviposition probability consistently increased as penetration force decreased and pH increased. Oviposition probability sometimes increased as TSS increased. Second, raspberries and blueberries in unsprayed fields had substantially lower infestation in ripening fruit compared to ripe fruit. There was no or minimal infestation in green fruit. Third, given that skin penetration force influences oviposition, practices used to improve fruit quality were examined in laboratory no-choice cages for potential reduction of oviposition. Blueberry fruit sprayed with calcium silicate in the field had greater penetration force and firmness and reduced number of eggs laid by D. suzukii compared to untreated fruit. Other calcium-based treatments increased Ca content and firmness of fruit relative to untreated fruit. Timing of insecticide spray for D. suzukii might be delayed until fruit become susceptible.

Many predatory arthropods are nocturnal, yet the potential contribution of nocturnal predators to biological control is often overlooked. The soybean aphid, Aphis glycines Matsumura, has emerged as a significant pest of soybean in the North Central US. Soybean aphid biological control research has focused on diurnal predators. Here, we used video cameras to continuously monitor soybean plants infested with soybean aphids, compare the diurnal and nocturnal predator communities on those plants, and assess predator activity during different times of day. Different predator communities were observed being active on soybean during day and night. Coccinellids and anthocorids dominated the diurnal predator community, while Opiliones and Araneae dominated the nocturnal predator community. Nocturnal and diurnal predators were recorded being active for similar rates per hour. Future research is needed to clarify the significance of arachnid predators and other nocturnal generalists to soybean aphid biocontrol.