Tephritid flies in the genus Rhagoletis are pests of many
commercially grown fruits in North America, infesting apples,
blueberries, cherries and walnuts. The apple maggot (R.
pomonella (Walsh)) and blueberry maggot (R. mendax Curran)
belong to a complex of closely related species (the pomonella
species group) that are morphologically similar, yet distinguishable
using multiple genetic and host use characteristics. Species
identification of field-trapped individuals is not trivial, and
population-level and phylogenetic relationships of pomonella
group species are complex. The objectives of this study were to
determine if we could use amplified fragment length polymorphism
(AFLP) markers to distinguish between the apple maggot and the
closely related snowberry fly (R. zephyria Snow), and to
detect structure within blueberry maggot populations. Apple maggot
has recently been detected in central and northwestern Washington
State, raising concern that it is expanding its range into these
areas, where R. zephyria is a native species. Current
identification methods rely on continuously varying morphological
characteristics, and it is sometimes difficult to determine if
trap-caught adults are apple maggots or snowberry flies. Using AFLPs,
the apple maggot and the snowberry fly can readily be distinguished
from one another. A screen of 35 AFLP primer combinations yielded two
combinations that produced bands unique to R. pomonella or
R. zephyria. Neighbor-joining analysis showed that, in
general, R. pomonella, R. zephyria and R. mendax
each clustered coherently, with R. pomonella and R.
mendax as sibling species. Blueberry maggot has been at the
center of recent quarantine issues between the US and Canada. To
determine if an observed blueberry maggot infestation arose via pest
introduction or from an endemic resident population, we used 3 AFLP
primer pairs to score genotypes of >50 individuals representing 8
R. mendax populations. We have yet to discover any discernible
population structure within R. mendax based on these data.
Species 1: Diptera Tephritidae Rhagoletis pomonella (apple maggot)
Species 2: Diptera Tephritidae Rhagoletis zephyria (snowberry fly)
Species 3: Diptera Tephritidae Rhagoletis mendax (blueberry maggot)
Keywords: species identification, amplified fragment length polymorphism (AFLP)
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA