Occurrence of late-emerging populations of the blueberry maggot fly (Diptera : Tephritidae)

Monitoring of adult flight patterns of the blueberry maggot fly, Rhagoletis mendax Curran, in New Jersey, indicated that the adults are active over a much longer period than previously reported. Captures on Pherocon AM traps over two seasons in wild sites and commercial fields of highbush blueberry, Vaccinium corymbosum L. (Ericaceae), showed that adult flies are present f or most of the period from early July to early November. Trap captures in w ild sites peaked during July-August, whereas in some commercial fields, pea k captures were recorded in September. Emergence patterns were determined b y collecting pupae from a wild site and a commercial field at the rime of p eak fruit infestation. The following year, the wild-site and commercial-fie ld populations showed distinct emergence periods that were in broad agreeme nt with trap captures at these locations. Comparison of an allozyme locus, using individuals collected in commercial blueberry fields, both on Pheroco n AM traps and from infested Fruit, confirmed that these populations were R . mendax and not any of the sibling species with a. similar flight period. These data show that there are considerable phenological differences betwee n some R, mendax populations. Given this plasticity, current debates on evo lutionary mechanisms in flies of the genus Rhagoletis Loew should consider that the Flight period of R. mendax is probably neither a major limiting fa ctor in the use of hosts with different fruiting schedules nor an effective premating isolation mechanism with respect to other sibling species.