Jim Smith
Research - Ongoing Research Projects in Rhagoletis

3. Development of DNA fingerprinting technology for identification and genetic characterization of apple maggot and blueberry maggot

Outcomes

a. Grant Support from MSU GREEEN

• Progress Report (6 month)
• Progress Report (12 month)

b. Poster Presentation at the Annual Meeting of the Entomological Society of America, San Diego CA, Dec. 8-12, 2001

Title: Use of amplified fragment length polymorphism markers to determine relationships of populations and closely related species in the genus Rhagoletis (Diptera: Tephritidae)

Authors: Jim Smith, Vesna Gavrilovic, Dan Ducat, Angela Roles, and Jessica Wolf.

Abstract

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.