Diurnal and Seasonal Activity Patterns of Drosophilid Species (Diptera: Drosophilidae) Present in Blackberry Agroecosystems With a Focus on Spotted-Wing Drosophila

Drosophilid species with different life histories have been shown to exhibit similar behavioral patterns related to locating and utilizing resources such as hosts, mates, and food sources. Drosophila suzukii (Matsumura) is an invasive species that differs from other frugivorous drosophilids in that females lay eggs in ripe and ripening fruits instead of overripe or rotten fruits. We hypothesized that there may be diurnal and/or seasonal patterns associated with the movement of drosophilid species into and out of crop fields and their attraction to fermentation-odor-based monitoring traps, and that D. suzukii would conform to similar patterns. To test these hypotheses, we deployed passive, 2-headed Malaise traps between crop fields and wooded edges to simultaneously catch flies moving into and out of crop fields. We also deployed monitoring traps with a fermentation-based bait between crop fields and wooded edges and within crop rows. Traps were deployed weekly in June–August in 2014 and 2015 at two commercial blackberry farm in Cleveland County, NC, and were checked hourly for 24 h, except during darkness. Both D. suzukii and other drosophilid species moved between crop fields and wooded edges and were attracted to monitoring traps primarily during the morning and evening hours. Whereas other drosophilids were captured in traps throughout the season, few D. suzukii were caught in traps until early to mid-July in both years and increased as the season progressed. Understanding D. suzukii movement and activity patterns is essential for the development of effective management strategies

Diurnal and Seasonal Activity Patterns of Drosophilid Species (Diptera: Drosophilidae) Present in Blackberry Agroecosystems With a Focus on Spotted-Wing Drosophila

Drosophilid species with different life histories have been shown to exhibit similar behavioral patterns related to locating and utilizing resources such as hosts, mates, and food sources. Drosophila suzukii (Matsumura) is an invasive species that differs from other frugivorous drosophilids in that females lay eggs in ripe and ripening fruits instead of overripe or rotten fruits. We hypothesized that there may be diurnal and/or seasonal patterns associated with the movement of drosophilid species into and out of crop fields and their attraction to fermentation-odor-based monitoring traps, and that D. suzukii would conform to similar patterns. To test these hypotheses, we deployed passive, 2-headed Malaise traps between crop fields and wooded edges to simultaneously catch flies moving into and out of crop fields. We also deployed monitoring traps with a fermentation-based bait between crop fields and wooded edges and within crop rows. Traps were deployed weekly in June–August in 2014 and 2015 at two commercial blackberry farm in Cleveland County, NC, and were checked hourly for 24 h, except during darkness. Both D. suzukii and other drosophilid species moved between crop fields and wooded edges and were attracted to monitoring traps primarily during the morning and evening hours. Whereas other drosophilids were captured in traps throughout the season, few D. suzukii were caught in traps until early to mid-July in both years and increased as the season progressed. Understanding D. suzukii movement and activity patterns is essential for the development of effective management strategies

Influence of edible fruit coatings on \u3ci\u3eDrosophila suzukii\u3c/i\u3e (Matsumura) (Diptera: Drosophilidae) oviposition and development

Drosophila suzukii (Matsumura) is a highly invasive vinegar fly recently detected in the United States that severely threatens the viability of soft skinned fruit production. Insecticides mitigate some of this damage, but alternative methods to manage D. suzukii infestation are needed. We tested three edible coatings to determine if they could prevent or reduce oviposition by D. suzukii females or affect immature survivorship and development in two important host crops, blueberry and raspberry. None of the coatings prevented oviposition, but some reduced the number of eggs laid. Two carnauba wax-based coatings, PrimaFresh 45 and Raynox, dramatically reduced survivorship of immature D. suzukii in raspberries, but not in blueberries. Our results suggest that obtaining thorough, even coverage in the field will be essential if edible coatings are to be used as a management strategy for D. suzukii

Effects of an Unregistered Insecticide on Adult Spotted Wing Drosophila Mortality and Field Infestation Rates, 2015

The effectiveness of an unregistered material at reducing Drosophila suzukii (SWD) infestation rates in blackberry field plots and its toxicity to adult SWD in laboratory bioassays was tested during the 2015 growing season. Field trials were conducted at the Sandhills Research Station near Jackson Springs, NC, in a 0.11-acre planting consisting of two rows of ‘Ouachita’ blackberries. Six treatments, including an untreated check (UTC), were applied to 5-plant plots and were arranged in an RCB design with four replicates per treatment, blocked by row, with two blocks per row. Delegate was the standard material. Some of the treatments were combined with an adjuvant, Syntact, at a concentration recommended by the manufacturer (Table 1). Applications were made twice, on 11 and 30 Jun. Treatments were applied to both sides of each row to fully cover plants using a CO2- pressurized backpack sprayer fitted with three flat fan nozzles at 45 psi pressure and 50 gal/acre spray volume. The desired application frequency for these materials is 7 days; however, additional applications could not be made due to unseasonably hot weather. Ten to 20 ripe berries, depending on availability, were collected from the middle three plants in each plot pre-treatment and 7 days after treatment (DAT) to measure infestation in the field. Fruit were held in plastic containers vented with fine mesh on the bottom to allow fruit to drain at 20°C, 65% RH, and 12:12 (L:D) h conditions. After 7 days, larvae and pupae were counted to determine infestation rates per berry

\u3ci\u3eDrosophila suzukii\u3c/i\u3e infestation in ripe and ripening caneberries

Drosophila suzukii (Matsumura) is a highly invasive vinegar fly that was first detected in the continental United States in 2008. Females use their saw-like ovipositor to lay eggs in soft-skinned fruits and severely threaten the viability of raspberry, blackberry, blueberry, cherry, and strawberry production. In a recent study, females in no-choice laboratory bioassays laid eggs in ripening blueberries and blackberries. However, most of the eggs failed to develop, perhaps because the ripening process was interrupted in the prematurely-harvested fruit. We hypothesized that eggs laid in ripening fruit in a field may be able to complete development as the fruit continues to ripen. To test this hypothesis, we used fine mesh cages to prevent later egg laying by D. suzukii in fruit at several ripeness stages: green-pink, pink, and ripe raspberries and in green-pink, red, purple, and ripe blackberries. We collected the fruit once they were ripe, and reared out and counted all D. suzukii present. This experiment was conducted at two locations during 2013 and 2014, one with very high fly populations and one with low populations. Very few flies emerged from blackberry clusters that were bagged at the green-pink stage, and in general, more flies emerged from clusters bagged at later stages of ripening (purple and red blackberries and pink raspberries) than from green-pink fruit. Knowing what ripeness stages are susceptible to D. suzukii infestation will help growers to better pinpoint when to begin applying management tools

Breeding biology and incremental benefits of outcrossing for the restoration wildflower, \u3ci\u3eHedysarum boreale\u3c/i\u3e Nutt. (Fabaceae)

Northern sweetvetch (Hedysarum boreale Nutt.) is an herbaceous perennial legume of the Rocky Mountains, USA, whose seed is desired for rehabilitating degraded plant communities. Through experimental pollinations, the necessity of pollinators was shown by the failure of autogamy, despite stigmas first becoming receptive in the bud in close proximity to the dehiscing anthers. Nonetheless, the species proved to be self-fertile, initiating as many fruits through selfing as outcrossing. Incremental benefits of outcrossing only later manifested in superior fruit development, seed maturation and seed germination. Farming of H. boreale can yield abundant viable seed if adequately visited by pollinating bees

Reproductive Status of \u3ci\u3eDrosophila suzukii\u3c/i\u3e (Diptera: Drosophilidae) Females Influences Attraction to Fermentation-Based Baits and Ripe Fruits

Drosophila suzukii (Matsumura) is an invasive species that is a devastating pest of soft-skinned fruit crops. Although much effort has been directed toward developing traps and attractants to monitor for D. suzukii, current monitoring tools do not reliably predict fruit infestation. The objective of this study was to determine if D. suzukii females at different developmental stages are differentially attracted to monitoring traps with fermentation-based baits and ripe fruits. Females were collected on the surface of traps, within traps, and on ripe fruits during three experiments at field locations in North Carolina, USA, and were dissected to determine their reproductive status. In general, females collected on ripe fruits were more likely to have mature eggs present in their ovaries and had higher numbers of mature eggs than females collected on the surface of or within monitoring traps. The results of this study have implications for D. suzukii monitoring and the development of effective baits for use in integrated pest management programs

“Hummingbird” floral traits interact synergistically to discourage visitation by bumble bee foragers

Pollination syndromes are suites of floral traits presumed to reflect adaptations to attract and utilize a “primary” type of animal pollinator. However, syndrome traits may also function to deter “secondary” flower visitors that reduce plant fitness through their foraging activities. Here we use the hummingbird-pollinated plant species Mimulus cardinalis as a model to investigate the potential deterrent effects of classic bird syndrome traits on bumble bee foragers. To establish that M. cardinalis flowers elicit an avoidance response in bees, we assessed the choice behavior of individual foragers on a mixed experimental array of M. cardinalis and its bee-pollinated sister species M. lewisii. As expected, bees showed a strong preference against M. cardinalis flowers (only 22% of total bee visits were to M. cardinalis), but surprisingly also showed a high degree of individual specialization (95.2% of total plant transitions were between conspecifics). To determine M. cardinalis floral traits that discourage bee visitation, we then assessed foraging responses of individuals to M. cardinalis-like and M. lewisii-like floral models differing in color, orientation, reward, and combinations thereof. Across experiments, M. cardinalis-like trait combinations consistently produced a higher degree of flower avoidance behavior and individual specialization than expected based on bee responses to each trait in isolation. We then conducted a series of flower discrimination experiments to assess the ability of bees to utilize traits and trait combinations associated with each species. Relative to M. lewisii-like alternatives, M. cardinalis-like traits alone had a minimal effect on bee foraging proficiency but together increased the time bees spent searching for rewarding flowers from 1.49 to 2.65 s per visit. Collectively, our results show that M. cardinalis flowers impose foraging costs on bumble bees sufficient to discourage visitation and remarkably, generate such costs through synergistic color-orientation and color-reward trait interactions. Floral syndromes therefore represent complex adaptations to multiple pollinator groups, rather than simply the primary pollinator

Evaluation of Foliar Insecticide Application Timing for the Control of Western Bean Cutworm in Field Corn, 2018

The objective of this field trial was to determine if application timing affects the efficacy of single applications of foliar insecticides at preventing feeding damage by the western bean cutworm (WBC), an important pest of corn and dry beans in the North American Corn Belt. This study was located at the University of Nebraska- Lincoln’s Henry J. Stumpf International Wheat Center in Perkins County, NE (40.856851°N, −101.701335°W). The experimental design used was an RCB design with a total of 10 treatments (three insecticides applied at three application timings, plus an untreated check) and four replications; the treatment design was an incomplete 4 × 3 factorial in which the UTC occurred during the ideal application timing only. Seeds of DKC62-95 (Monsanto Company, St. Louis, MO), a non-Bt hybrid with RR2 herbicide tolerance, were planted on 5 May 2018 using a commercial 8-row planter at 32,000 seeds/acre at approximately 1.40–1.75 inches deep in 30-inch rows. Individual plots measured 20 ft (8 rows) wide x 35 ft long. Standard agronomic practices for the region were followed for irrigation, fertilization, and weed management inputs. No insecticide applications were made other than the experimental treatments

Ovipositional preference, fidelity, and fitness of \u3ci\u3eDrosophila suzukii\u3c/i\u3e in a co-occurring crop and non-crop host system

Drosophila suzukii (Matsumura) is a devastating pest of soft-skinned fruits including blackberries and raspberries. Management of this pest is focused on preventing infestation in crops, but non-crop hosts may play an important role in enabling D. suzukii to persist in the absence of cultivated hosts. Drosophila suzukii may also infest fruits of both crop and non-crop hosts concurrently. Our goals were to determine whether (1) D. suzukii prefers to oviposit in cultivated blackberry, Rubus L. subgenus rubus Watson, or American pokeweed, Phytolacca americana, a non-crop host commonly found along field edges, (2) D. suzukii prefers to oviposit into the same host from which it emerged, and (3) performance differs between D. suzukii progeny that develop in blackberries or pokeweed berries. Although the pest was able to infest both hosts at the same rate, we found that D. suzukii females emerging from pokeweed preferred to oviposit into blackberries, while females emerging from blackberry had no preference. Progeny that developed in blackberries were more fit than progeny that developed in pokeweed berries based on several measures. In field locations, cultivated blackberries and pokeweed berries only overlapped in availability for a short period of time, and infestation rates were variable between blackberries and pokeweed berries collected during that period. Nonetheless, these results suggest that noncrop hosts may facilitate the invasion of D. suzukii and perpetuate infestation of cultivated hosts under certain circumstances