Impact of prolonged absence of low temperature on adult eclosion patterns of western cherry fruit fly (Diptera: Tephritidae)

Authors: Neven, Lisa; Yee, Wee

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2017
Publication Date: 5/15/2017
Citation: Neven, L.G., Yee, W.L. 2017. Impact of prolonged absence of low temperature on adult eclosion patterns of western cherry fruit fly (Diptera: Tephritidae). Environmental Entomology. 46(3):708-713. https://doi.org/10.1093/ee/nvx064.
DOI: https://doi.org/10.1093/ee/nvx064

Interpretive Summary: The western cherry fruit fly is a quarantine pest of sweet cherries in the Pacific Northwest of the U.S. that is adapted to cold winters. The ability of this pest to establish and spread to markets with warm countries is affected by its ability to survive in warm temperatures. Personnel at the USDA-ARS laboratory in Wapato, WA conducted a 3-year study to examine the effects of prolonged no chilling on fly emergence. It was found that a lack of chilling of diapausing pupae reduced the number of flies that emerged and delayed emergence times but did not prevent fly emergence. Results are important in that they can be used to develop revised models to predict fly emergence in warm climates.

Technical Abstract: The western cherry fruit fly, Rhagoletis indifferens (Curran) (Diptera: Tephritidae), is a serious pest of cherries (Prunus spp.) in the Pacific Northwest of the U.S.A. Previous research suggests that R. indifferens is unlikely to establish in commercial cherry production areas in California and in tropical export markets as chilling temperatures in those regions appear insufficient to support diapause completion. However, it is unclear how prolonged duration of non-chill periods affects diapause completion in R. indifferens. Here, we examined the impact of no-chill exposure for 40 wks on diapause completion in R. indifferens. Fly eclosion from non-chilled pupae exhibited a bimodal distribution. The first major peak, comprising 3.2% of the total fly emergence, occurred at 1-10 wks. The second major peak, comprising the remaining 96.8%, occurred at a mode of approximately 30 wks. Based on responses to non-chill and chill temperatures, there were three distinct pupal diapause groups: the first eclosion group was likely non-diapausing pupae; the second eclosion group was likely diapausing pupae; a third group that remained viable but did not produce adults after 40 wks may represent multiple year diapausers. We suggest that eclosion of R. indifferens after prolonged exposure to non-chill temperatures needs to be incorporated into models used to predict fly establishment in warm climates.