Pollination Application Of Honey Bees In Pear Orchard

Pear is a high-value commercial fruit in China and exhibits fully self-incompatibility,depends entirely on cross-pollination to set fruits.Pear pollination requires determining the foraging behavior of honeybees and the factors that influence their pollination efficiency.In this thesis,we conducted three separate but related experiments in major pear-growing areas,Shanxi Province,China in the 2015-2017 during pear flowering seasons.In the first trial,comparative analysis of pear flower foraging behavior of Apis cerana and Apis mellifera was performed under the natural conditions.Some interesting findings were obtained that A.mellifera shows variable preferences: vigorously foraging on pear flower on the first day of observation,but shifted to non-target floral resources on other experimental days.Conversely,A.cerana start foraging earlier and for wider peak time without shifting the preference to other competitive flowers.These findings suggested that A.cerana is better adapted to pear pollen collection as the species evolved with native pear trees in Asia,regardless of the current colony reduction to use the species for pear pollination compared to the expanding use of A.mellifera.In the second trial,to use the advantage of A.mellifera,we investigated whether colony manipulations affects honey bees pear foraging behavior.We particularly assessed the pollen collection efficiency of foragers through pollen trapping and simulative sugar syrup feeding.Our results show that colonies and individual pollen foragers could vary their pollen foraging strategies following colony manipulations.The assumption is that pollen depletion by pollen trapping(PT)and simulative feeding of sugar syrup(SS)in the colonies enhances the pollen collection activity of honeybees to fulfill the pollen shortage in the colony.Colony manipulation using PT and SS are useful techniques.Moreover,the combination of pollen trapping and sugar syrup feeding(PTSS)was the most effective techniques to increase pollen collection.The technique is important to enhance pollen collection of less preferred pear flowers and further useful when pollination of short flowering period is required.In the last trial,the volatiles compositions in anthers and nectar of pear were investigated using SPME coupled with gas chromatography-mass spectrometry(GC/MS).The results demonstrate that volatile scents in anthers and nectar show differences in the absolute numbers and relative abundance and varied among pear cultivars.The three pear cultivars(Suli,Yali,and Hongxiangsu)emit similar type of volatiles with different relative abundances whereas;cultivar Bali comparatively emits distinctive and larger numbers of volatiles,which may elicit the differential visitation of honey bees.This study was associated in more natural conditions by comparing the honey bees foraging preferences on different pear cultivars planted in the same orchard.Honey bees significantly prefer for cultivar Bali indicating that their foraging intensity may linked with distinctive volatiles emitted in pear.In conclusion,A.cerana outperforms A.mellifera with regard to pear pollen collection and pollination.Considering the expansion of A.mellifera colonies in China,we provide new insights of colony manipulation that alter the honey bee behavior at both individual and colony levels jointly increase the pear pollen collection,which possibly enhances the pollination.Pear volatile scents are equally important to characterize and identify the commercial pear cultivar intensively pollinated by commercial honey bees.