|St. Jean, Gilbert|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2013
Publication Date: 6/30/2013
Citation: St. Jean, G., Egan, S.P., Yee, W.L., Feder, J.L. 2013. Genetic identification of an unknown Rhagoletis fruit fly infesting Chinese crabapple (Malus spectabilis): implications for apple pest management. Journal of Economic Entomology. 3:1511-1515. Interpretive Summary: The apple maggot fly is an important quarantine pest of apples in the Pacific Northwest of the U.S. Different fruit flies can infest fruit also used by apple maggot, making the larvae difficult to identify and hindering control efforts. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA and the University of Notre Dame in Notre Dame, IN determined if molecular methods could be used to identify larvae reared from crabapple, a host of apple maggot. Based on five microsatellite loci, the identity of the crabapple-infesting larvae was determined to be western cherry fruit fly and not apple maggot. This result is important because it suggests rapid, accurate, and inexpensive DNA-based detection tools could be used to identify unknown fruit fly larvae from fruit.
Technical Abstract: The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is a serious introduced quarantine pest in the apple-growing regions of central Washington and Oregon. In August 2011, seven fly larvae of unknown origin were discovered infesting fruit of an exotic Chinese crabapple, Malus spectabilis (Aiton) Borkhausen, in Kennewick, Benton County, Washington. If confirmed, Chinese crabapple would have represented a new host for R. pomonella in Washington and would have triggered quarantine measures in a surrounding three-county region of the state. Here, we establish based on five microsatellite loci the identity of the crabapple-infesting larvae as the western cherry fruit fly, R. indifferens Curran, and not R. pomonella. Morphological analysis of six flies reared to adulthood confirmed the genetic identification. The results avoided enacting costly quarantine measures and demonstrated the utility of integrating rapid genetic identification methods with field surveys of economic pests. We discuss current ongoing efforts to develop rapid, accurate, and inexpensive on site DNA-based detection tools for R. pomonella that would have general applicability for biocontrol of pest insects.