Showing papers by "Raphael A. Stern published in 2012"

Adding bumblebees (Bombus terrestris L., Hymenoptera: Apidae) to pear orchards increases seed number per fruit, fruit set, fruit size and yield

Abstract: SummaryThe European pear (Pyrus communis) cultivars ‘Spadona’ and ‘Coscia’ exhibit full self-incompatibility, and therefore fruit production depends entirely on cross-pollination, which is carried out mainly by honeybees (HB), the ultimate pollinators of pear. To increase the efficiency of HB pollination, colony numbers are doubled or introduced sequentially; nevertheless, yields remain relatively low and fruit are small due to the low number of seeds per fruit. In the present research, we studied the effect of adding bumblebees (BB) to the HB colonies. Adding BB hives to pear orchards 10 d before bloom, at a density of ten hives ha–1, improved the percentage fruit-set, fruit size, and also sometimes, fruit yield. These positive results were due to a large increase in seed numbers per fruit, especially in ‘Spadona’ which had only one-to-three seeds per fruit when pollinated only by HB, compared to four-to-six seeds after pollination with HB + BB. There was a strong positive correlation between the number ...