ECOLOGY AND POPULATION BIOLOGY Geographic and Ecological Overlap of Parasitoid Wasps Associated With the Rhagoletis pomonella (Diptera: Tephritidae) Species Complex

Oneof the fundamentalquestions inevolutionaryecology seeks tounderstandhownew biodiversity is created and structured into communities. The apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), a model for rapid ecological speciation via host plant shifting for phytophagous insects, and its parasitoid community can offer insight into answering this and other related questions. Speciation of Rhagoletis also seems to be driving sequential speciation in a host speciÞc parasitoid wasp Diachasma alloeum (Muesebeck) (Hymenoptera: Braconidae). However, biological and geographic information regardingD. alloeum and other parasitoids attacking ßies in the genus Rhagoletis is sorely lacking, a problem that complicates the study of their evolution. Here, we present a synthesis of the geographic ranges and extended host associations of Rhagoletis-attacking parasitoids and testwhether parasitoids can overlap in host use. In particular, we askwhether 1)wasps thatco-occur in sympatryattackdifferent life stagesof theßy, 2) locallyco-occurringwasps share some ßy species in common but not others, 3) wasps differ in local abundance on those ßy hosts they share in common, and 4) wasps vary on a regional scale in their geographic distributions. We use both collections and published records to answer the above-mentioned questions. A strong understanding of the Rhagoletis-attacking parasitoid distributions will facilitate future study of sequential radiation in this system.