Low temperature duration and adult rearing regimes affect eclosion of Rhagoletis indifferens (Tephritidae: Diptera)

Authors: Neven, Lisa; Wakie, Tewodros; Yee, Wee

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2020
Publication Date: 4/25/2020
Citation: Neven, L.G., Wakie, T., Yee, W.L. 2020. Low temperature duration and adult rearing regimes affect eclosion of Rhagoletis indifferens (Tephritidae: Diptera). Environmental Entomology. 49(3):660-666. https://doi.org/10.1093/ee/nvaa044.
DOI: https://doi.org/10.1093/ee/nvaa044

Interpretive Summary: The western cherry fruit fly is a quarantine pest of sweet cherries in the Pacific Northwest of the U.S. that overwinters as diapausing pupae. Exposing pupae to different low temperature durations and rearing conditions affect the emergence of the flies. Scientists at the USDA-ARS in Wapato, WA determined the effects of holding apple maggot pupae at at low temperature for up to 30 weeks, followed by different post-chill rearing conditions, while monitoring fly emergence over subsequent 40 weeks. Pupae chilled for less than 10 weeks took significantly longer to emerge as flies. However, when pupae were chilled for 15-30 weeks, emergence was more synchronous and occurred within 5-7 weeks after being moved to post-chill climate treatments. More flies emerged from pupae who were held for >15 weeks of chilling. The pattern of fly emergence in respect to the duration of low temperature exposure may be indicative of univoltine insect species with obligate diapause that may span over 2 seasons. This information can be used to modify trapping timing for this pest in respect to ongoing climate change patterns

Technical Abstract: The western cherry fruit fly, Rhagoletis indifferens Curran, is a quarantine pest of sweet cherries in the Pacific Northwest of the U.S. that overwinters as diapausing pupae. Eclosion responses of R. indifferens puparia to different low temperature durations and post-diapause conditions affect the pest status of the fly. Here, we determined the effects of holding R. indifferens puparia at 3°C for 0, 1, 2, 5, 10, 15, and 20 weeks on adult eclosion times and rates at two simulated temperate and two simulated tropical climate treatments over 40 weeks. When puparia were chilled 0, 1, or 2 weeks, adult eclosion across the four climate treatments displayed a bimodal distribution with low eclosion at 3 weeks and high eclosion at 23-35 weeks. When puparia were chilled = 10 weeks, there was a weaker bimodal distribution. However, when puparia were chilled 15-30 weeks, eclosion was more synchronous and occurred at 5-7 weeks across the four post-chill climate treatments. Eclosion was greater at a post-diapause temperature of 26°C than 23°C. Timing to 50 percent eclosion was faster at longer photoperiod (16:8 L:D) than shorter (12:12 L:D). The bimodality of eclosion in respect to the duration of low temperature exposure may be indicative of univoltine insect species with obligate diapause that may span over two seasons