Habitat-specific flight period in the cherry fruit fly Rhagoletis cingulata (Loew) (Diptera: Tephritidae)

Flight periods of the cherry fruit fly, Rhagoletis cingulata (Loew), were compared in the major sweet and tart cherry-growing regions of Michigan, among neglected orchards, managed orchards, and natural areas containing the ancestral host, black cherry. Traps were deployed from early June to late September 2005 and 2006. Captures indicated that cherry fruit fly has an early flight (June-July) in neglected orchards, a mid-season flight peaking immediately after harvest (June-August) in managed orchards, and an extended flight covering most of the season (June-September) in natural areas. We found that the period of fruit infestation mirrored the flight period in neglected and managed orchards. In natural areas, we found infestation late in the season only. The relative emergence periods for adults reared from pupae collected from the three habitats and maintained under the same conditions coincided with adult flight periods for each habitat. We also studied factors related to fruit availability that may have a role in shaping the flight periods. Fruit abundance decreased rapidly early in the season in neglected orchards, whereas in managed orchards, fruit left after harvest remained on the trees until late August. Measurements of fruit size and skin firmness revealed that fly activity in neglected and managed orchards began immediately after fruit increased in size and skin firmness decreased, whereas in natural areas, the flight began before fruit matured. In managed orchards, fruit harvest and insecticide sprays likely maintain the late flight period of resident fly populations by preventing the use of fruit earlier in the season. However, a significant proportion of these resident flies may still emerge before harvest and increase the risk of costly fruit infestation.