Differential water deprivation tolerances of adult Rhagoletis indifferens and Rhagoletis pomonella (Diptera: Tephritidae) as a possible factor affecting their distributional abundances in Washington State, U.S.A.

Authors: Yee, Wee; Rose, Alexander; MILNES, JOSHUA - Washington Department Of Agriculture; FEDER, JEFFREY - University Of Notre Dame

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2024
Publication Date: 10/16/2024
Citation: Yee, W.L., Rose, A.C., Milnes, J.M., Feder, J.L. 2024. Differential water deprivation tolerances of adult Rhagoletis indifferens and Rhagoletis pomonella (Diptera: Tephritidae) as a possible factor affecting their distributional abundances in Washington State, U.S.A.. Environmental Entomology. nvae096. https://doi.org/10.1093/ee/nvae096.
DOI: https://doi.org/10.1093/ee/nvae096

Interpretive Summary: Cherry fruit fly and apple maggot fly are quarantine pests of cherry and apple, respectively, in WA state. Cherry fruit fly is abundant in commercial fruit growing areas in central WA while apple maggot is rare there, but reasons for this are not well understood. Personnel at USDA-ARS in Wapato, WA, Washington State Department of Agriculture in Yakima, WA and the University of Notre Dame in IN determined the effects of depriving cherry fruit flies and apple maggot flies of water on their longevity. It was found that cherry fruit flies survived longer without water than apple maggot flies. This result is important in that it suggests the dry conditions in central WA play a role in suppressing apple maggot populations, such that apple maggot flies there may never develop large populations near commercial apple orchards.

Technical Abstract: Insects that evolved in mesic regions may have difficulty establishing in xeric regions. Rhagoletis pomonella (Walsh) (Diptera: Tephritidae) was introduced into drier western North America from mesic eastern North America while Rhagoletis indifferens Curran is native to western North America. Here, we predicted that R. indifferens survives water deprivation longer than R. pomonella, as R. indifferens is more abundant than R. pomonella in dry central Washington (WA) State, U.S.A. Sweet and bitter cherry-origin R. indifferens and apple- and hawthorn-origin R. pomonella from xeric central or mesic western WA were provided water throughout or were water-deprived at 2–4 and 14–18 d old and held at 20ºC or 30/31ºC and daily survival recorded. At 20°C and even 30°C, western WA apple-origin R. pomonella provided water survived longer than sweet-cherry origin R. indifferens. When water deprived, however, 2–4 d old R. indifferens, although smaller, survived significantly longer than western WA apple-origin R. pomonella of the same age. This was also generally true for 14–18 d old flies, although differences were not always significant. Central WA large-thorn hawthorn-origin R. pomonella survived water deprivation significantly longer than western WA apple-origin R. pomonella, although shorter than R. indifferens. Water-deprived flies of both species survived longer at 20ºC than 30/31ºC. Results suggest that low water availability rather than high temperature contributes to lower R. pomonella than R. indifferens abundances in central WA, with R. pomonella populations in that region differing from western WA R. pomonella with respect to tolerance of xeric climates.