Search

Drosophila suzukii (Matsumura) is a global pest attacking various berry crops. D. suzukii lays eggs in damaged and in intact wine grape berries of the most soft-skinned varieties. Here, we describe the relative host utilization of different wine grape cultivars grown in Northern Italy and Oregon. Assessments of host berry utilization were performed in both field and laboratory settings. Results were correlated to physiological changes occurring during grape berry development starting at veraison and concluding during harvest. We found that oviposition increased with an increase in sugar content and a decrease of acidity levels. Oviposition increased with a decrease of penetration force. Penetration force, as a measure of skin hardness, is a critical component of host selection among the D. suzukii-exposed cultivars. We demonstrated that incised berries are more favorable for D. suzukii oviposition and as a nutrient substrate. Increased presence on wine grapes, as indicated by egg laying and increased longevity, was observed for flies that were exposed to incised berries as opposed to fully intact berries. D. suzukii flies can be found feeding on damaged wine grapes during the harvest period, especially when the skins of berries are negatively impacted due to cracking, disease, hail injury, and bird damage. Such an increase of feeding and oviposition may increase the likelihood of spoilage bacteria vectoring due to D. suzukii. [ABSTRACT FROM AUTHOR]

Grape mealybug, Pseudococcus maritimus (Ehrhorn) (Hemiptera: Pseudococcidae), is a pest of grape vines, Vitis vinifera (Vitales: Vitaceae) and a known vector of several strains of grapevine leafroll-associated virus. Seasonal increase and decline of Ps. maritimus populations on wine grapes is described in each of three important grape growing regions in Oregon using pheromone-baited traps and visual monitoring. Delta traps and genomic verification of collected sessile stages found that only Ps. maritimus is present in Oregon vineyards. Seasonal pheromone-baited trapping and visual surveys during 2010 and 2011 identified two population peaks for adult male flight and sessile developmental stages on vines in Southern Oregon and the Columbia Basin. Willamette Valley vineyards identified one peak male flight period using pheromone-baited traps but no sessile individuals were found in visual surveys. Seasonal developmental stages are described for Southern Oregon and the Columbia Basin. First instar stages generally were observed one month before peak male flight and were less abundant during peak flight. Adult females and late instar stages were found on vines at the peak of male flight. Pheromone monitoring identified the presence of mealybug populations in viticultural areas, even when intensive visual surveys were unable to do so. [ABSTRACT FROM AUTHOR]

Developmental parameters of protogyne Calepitrimerus vitis (Nalepa) (Acari: Erlophyidae) were determined at 12, 15, 17, 22, 25, 28, 31, and 34°C to better understand seasonal activity, population growth, and ultimately more effectively manage pest mites in wine grapes. Net reproductive rate (R0) was greater than zero at all temperatures with the maximum R0 (9.72) at 25°C. The lowest estimated R0 (0.001) occurred at 34°C. There was a gradual decrease in mean generation time (T) as temperatures increased from 17 to 31°C. The shortest and longest generation time was recorded at 31°C (T = 5.5 d) and 17°C (T = 17.5 d). Rates of natural increase were lowest at 17°C (0.035) and increased with increasing temperatures, respectively. The peak rate of natural increase value (0.141) was at 25°C. Estimations for minimum and maximum developmental thresholds were 10.51 and 39,19°C, respectively, while the optimum developmental temperature was 26.9°C. The thermal constant for egg to adult development was estimated at 87.7DD. The highest fecundity was observed at 25°C. These parameters indicated that mites begin feeding at the onset of shoot growth when tissue is most susceptible in spring. Historical weather data showed that vines are in this susceptible growth stage for longer periods in the cool Willamette Valley compared with warmer Umpqua and Applegate/ Rogue Valley regions. Estimation of degree-days indicated when deutogyne mites move to overwintering refuge sites. Degree-day accumulations indicated up to 14 generations per growing season. [ABSTRACT FROM AUTHOR]