Steve Castagnoli

Red ‘Anjou’ pear has a higher photoprotective capacity than green ‘Anjou’

Photoprotective function of anthocyanins along with xanthophyll cycle and antioxidant system in fruit peel was investigated in red Anjou vs green Anjou pear (Pyrus communis) during fruit development and in response to short-term exposure to high light. The sun-exposed peel of red Anjou had higher maximum quantum yield of photosystem II (F(V)/F(M)) than that of green Anjou and both the sun-exposed peel and the shaded peel of red Anjou had smaller decreases in F(V)/F(M) after 2-h high light (photon flux density of 1500 mumol m(-2) s(-1)) treatment than those of green Anjou. At the middle and late developmental stages, the xanthophyll cycle pool size on a chlorophyll basis, the activity of superoxide dismutase, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) and the level of reduced ascorbate and total ascorbate pool in the sun-exposed peel were either the same or lower in red Anjou than in green Anjou, whereas the xanthophyll cycle pool size on a chlorophyll basis and the activity of APX, catalase, MDAR, DHAR and GR in the shaded peel were higher in red Anjou than in green Anjou. It is concluded that red Anjou has a higher photoprotective capacity in both the sun-exposed peel and the shaded peel than green Anjou. While the higher anthocyanin concentration along with the larger xanthophyll cycle pool size and the higher activity of some antioxidant enzymes may collectively contribute to the higher photoprotective capacity in the shaded peel of red Anjou, the higher photoprotective capacity in the sun-exposed peel of red Anjou is mainly attributed to its higher anthocyanin concentration.

Spatial Analysis of Seasonal Dynamics and Overwintering of Drosophila suzukii (Diptera: Drosophilidae) in the Okanagan-Columbia Basin, 2010–2014

Abstract Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was monitored from 2010 to 2014 in 314–828 sites located in interior fruit-growing regions of OR and WA, United States, and BC, Canada, using traps baited with apple cider vinegar or sugar-water-yeast. Seasonal population dynamics and sex ratios were summarized for berry, cherry, stone fruit, grape, non-crop host plants, non-host sites, and for conventional IPM, certified organic, backyard, and feral sites, by region and year. Overwintering was detected in all regions and years, despite winter temperatures below -17°C. A spatial analysis was conducted using a Geographic Information System (GIS), daily weather data, geomorphometric measures of terrain, distance to water, and other variables, at each site. Overwintering success at a site, measured as Julian week of first capture of D. suzukii, was significantly related (R 2 = 0.49) in cherry habitats to year, agronomic treatment, and number of winter days with temperatures >-5°C. In berry, cherry, stone fruit and grape habitats, 2011–2014, it was significantly related (R 2 = 0.42) to year, agronomic treatment, the logarithm of peak population of D. suzukii in the prior autumn, latitude, elevation, and topographic wetness index. The results show that D. suzukii has adapted to exploit a succession of irrigated crops and feral habitats in mixed landscapes of a semi-arid region with cold winters and hot dry summers, and are shaping strategies for pest management and for biological control.