Life history phenology differences between southern and northern populations of the apple maggot fly, Rhagoletis pomonella

摘要

The textbook version of sympatric host race formation in Rhagoletis pomonella (Walsh) (Diptera: Tephritidae) features an ancestral hawthorn-infesting race and a derived apple race differing in life-history timing and response to host fruit odor. However, previous research has focused largely on northeastern North America. To investigate life-history timing in poorly studied southeastern North American populations with very diverse hosts, we performed common garden experiments on emergence time on six southern R. pomonella populations and four other R. pomonella species-group populations. Findings were: (1) the diverse adult emergence times of southern populations resulted largely from genetic differences; (2) some southern populations had bimodal emergence curves; (3) correlations of allozyme markers and emergence times were uncommon in southern populations; and (4) mean emergence times from common garden rearings and dates of field collection of the populations were strongly correlated.