Distinct Adult Eclosion Traits of Sibling Species Rhagoletis pomonella and Rhagoletis zephyria (Diptera: Tephritidae) Under Laboratory Conditions

Authors: Yee, Wee; GOUGHNOUR, ROBERT - Washington State University; FEDER, JEFFREY - University Of Notre Dame

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2020
Publication Date: 11/28/2020
Citation: Yee, W.L., Goughnour, R.B., Feder, J.L. 2020. Distinct Adult Eclosion Traits of Sibling Species Rhagoletis pomonella and Rhagoletis zephyria (Diptera: Tephritidae) Under Laboratory Conditions. Environmental Entomology. 50(1):173-182. https://doi.org/10.1093/ee/nvaa148.
DOI: https://doi.org/10.1093/ee/nvaa148

Interpretive Summary: The apple maggot fly and snowberry fly are genetically closely related flies that attack apple and snowberry fruit, respectively. In part because of their use of different host plants, their responses to various environmental factors may have diverged. Personnel at the USDA-ARS laboratory in Wapato, WA, Washington State University in Vancouver, WA, and the University of Notre Dame, Indiana, compared the timing of adult fly emergence after their pupae were chilled or not. After chilling, emergence distributions of apple maggot flies were more dispersed than of snowberry flies. When pupae were not chilled, many more apple maggot than snowberry flies emerged. Results are important in that they suggest greater genetic variation in apple maggot than snowberry flies, helping us understand how differences in basic biology could be affected by use of different host plants

Technical Abstract: Closely related phytophagous insects that have become reproductively isolated may have divergent responses to environmental factors. Rhagoletis pomonella (Walsh) and Rhagoletis zephyria Snow (Diptera: Tephritidae) are sibling, sympatric fly species found in western North America that attack and mate on plants of Rosaceae (~60 taxa) and Caprifoliaceae (three taxa), respectively, resulting in partial reproductive isolation. Rhagoletis zephyria evolved from R. pomonella and is native to western North America whereas R. pomonella was introduced there. Given that key features of the flies’ ecology and evolution differ, we predicted that adult eclosion patterns of the two flies from Washington State, U.S.A. are also distinct. When puparia were chilled, eclosion of apple- and black hawthorn-origin R. pomonella was significantly more dispersed, with less pronounced peaks, than of snowberry-origin R. zephyria within sympatric and non-sympatric site comparisons. Percentages of chilled puparia that produced adults were >67% for both species. However, when puparia were not chilled, from 13.5 to 21.9% of apple-origin R. pomonella versus only 1.2% to 1.9% of R. zephyria eclosed. The distinct differences in eclosion traits of R. pomonella and R. zephyria could be due to greater genetic variation in R. pomonella, associated with its use of a wider range of host plants displaying greater phenological variation in seasonal windows of fruit availability for oviposition and larval development than the snowberry hosts of R. zephyria