A multi-year collection inventory of bees and pollinating flies found in North Georgia apple orchards: comparing an early apple bloom with a late apple bloom

Colony Collapse Disorder in the European Honeybee (Apis mellifera) has generated interest in identifying endemic insect pollinators, which could replace or supplement the dwindling honeybee. In this study, four North Georgia apple orchards were sampled from March through October in both 2010 and 2011 to determine pollinator species presence and densities. Domesticated apple trees (Malus domestica) have an earlier flowering period than many other commercial agricultural crops in Georgia, with serious implications to which species are available for pollination. The 2010 and 2011 apple blooms were quite different. The 2011 apple bloom occurred very early (mid-March), while the 2010 apple bloom (early April) followed traditional patterns. As a result, significantly fewer bees and pollinating flies were available in the 2011 apple bloom, potentially reducing apple crop abundance. Typically in March, prior to the bloom, native pollinator species are present at low initial numbers, marginally increasing until the first blossoms open in early April. Upon flowering, both the diversity and abundances of native pollinator species explode, especially in Apoidea. Even though the apple bloom varied significantly during the two years, similar patterns of pollinator diversity were observed. Overall, Colletids, Andrenids and Apids proved to be the most prevalent of all native bee taxa from before and during the bloom, while many Halictids and Syrphids species steadily increased over the same period, maximizing well after the last apple blossoms had dropped. Calyptrate flies were consistently diverse and abundant throughout the study; the apple bloom had no effect on their numbers.