Larval Drosophila encounter and feed on a diverse microbial community within fruit. In particular, free-living yeast microbes provide a source of dietary protein critical for development. However, successional changes to the fruit microbial community may alter host quality through impacts on relative protein content or yeast community composition. For many species of Drosophila, fitness benefits from yeast feeding vary between individual yeast species, indicating differences in yeast nutritional quality. To better understand these associations, we evaluated how five species of yeast impacted feeding preference and development in larval Drosophila suzukii. Larvae exhibited a strong attraction to the yeast Hanseniaspora uvarum in pairwise yeast feeding assays. However, larvae also performed most poorly on diets containing H. uvarum, a mismatch in preference and performance that suggests differences in yeast nutritional quality are not the primary factor driving larval feeding behavior. Together, these results demonstrate that yeast plays a critical role in D. suzukii’s ecology and that larvae may have developed specific yeast associations. Further inquiry, including systematic comparisons of Drosophila larval yeast associations more broadly, will be necessary to understand patterns of microbial resource use in larvae of D. suzukii and other frugivorous species.

No abstract

No abstract

Spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), a vinegar fly of Asian origin, has emerged as a devastating pest of small and stone fruits throughout the United States. Tolerance for larvae is extremely low in fresh market fruit, and management is primarily achieved through repeated applications of broad-spectrum insecticides. These applications are neither economically nor environmentally sustainable, and can limit markets due to insecticide residue restrictions, cause outbreaks of secondary pests, and select for insecticide resistance. Sustainable integrated pest management programs include cultural control tactics and various nonchemical approaches for reducing pest populations that may be useful for managing D. suzukii. This review describes the current state of knowledge and implementation for different cultural controls including preventative tactics such as crop selection and exclusion as well as strategies to reduce habitat favorability (pruning; mulching; irrigation), alter resource availability (harvest frequency; sanitation), and lower suitability of fruit postharvest (cooling; irradiation). Because climate, horticultural practices, crop, and market underlie the efficacy, feasibility, and affordability of cultural control tactics, the potential of these tactics for D. suzukii management is discussed across different production systems.

1. While many studies have investigated non-target impacts of neonicotinoid seed treatments (NSTs), they usually take place within a single crop and focus on specific pest or beneficial arthropod taxa.2. We compared the impacts of three seed treatments to an untreated control: imidacloprid + fungicide products, thiamethoxam + fungicide products and fungicide products alone in a 3-year crop rotation of full-season soybean, winter wheat, doublecropped soybean and maize. Specifically, we quantified neonicotinoid residues in the soil and in weedy winter annual flower buds and examined treatment impacts on soil and foliar arthropod communities as well as on plant growth and yield.3. Unquantifiably low amounts of insecticide were found in winter annual flowers of one species in one site year, which did not correspond with our treatments.Although low levels of insecticide residues were present in the soil, residues were not persistent. Residues were highest in the final year of the study, suggesting some accumulation.4. We observed variable impacts of NSTs on the arthropod community; principle response curve and redundancy analyses exhibited occasional treatment effects, with treatments impacting the abundance of various taxa, including predators and parasitoids. Overall, foliar taxa were more impacted than soil taxa, and the fungicides occasionally affected communities and individual taxa. 5. Pest pressure was low throughout the study, and although pest numbers were reduced by the insecticides, corresponding increases in yield were not observed.6. Synthesis and applications. Pesticide seed treatments can impact arthropod taxa, including important natural enemies even when environmental persistence and active ingredient concentrations are low. The foliar community in winter wheat showed that in some cases, these impacts can last for several months after planting. Given the low pest pressure and lack of yield improvement in full-season soybean, double-cropped soybean, winter wheat and maize, we did not observe benefits that could justify the risks associated with neonicotinoid seed treatment (NST) use. Our results suggest that NSTs are not warranted in Maryland grain production, outside of specific instances of high pest pressure. | 937Journal of Applied Ecology DUBEY Et al.