Prolonged pupal dormancy is associated with significant fitness cost for adults of Rhagoletis cerasi (Diptera: Tephritidae)

In temperate areas, dormancy (diapause and/or quiescence) enables herbivorous insect species to persist and thrive by synchronizing growth and reproduction with the seasonal phenology of their host plants. Within-population variability in dormancy increases survival chances under unpredictable environmental changes. However, prolonged dormancy may be costly, incurring trade-offs in important adult fitness traits such as life span and reproduction. We used the European cherry fruit fly, Rhagoletis cerasi, a stenophagous, univoltine species that overwinters in the pupal stage for usually one or more years to test the hypotheses that prolonged dormancy of pupae has trade-offs with body size, survival and reproduction of the resulting adults. We used two geographically isolated populations of R. cerasi to compare the demographic traits of adults obtained from pupae subjected to one or two cycles of warm-cold periods (annual and prolonged dormancy respectively). Regardless of population, adults from pupae that experienced prolonged dormancy were larger than counterparts emerging within 1 year. Prolonged dormancy did not affect adult longevity but both lifetime fecundity and oviposition were significantly decreased. Extension of the life cycle of some individuals in R. cerasi populations in association with prolonged dormancy is likely a bet-hedging strategy.

Age specific fecundity rates of R. cerasi females obtained from pupae undergoing either annual (A) or prolonged dormancy (B). Green = 0 eggs/day; yellow = 1-5 eggs/day; red = 5 eggs/day. Populations from Macedonia (left column) and Peloponnesus (right column) have been tested.Highlights▸ Prolonged pupae dormancy positively affects adult size in Rhagoletis cerasi. ▸ Prolonged pupae dormancy did not affect adult survival rates. ▸ Prolonged dormancy reduces female fecundity to 1/3 that of females emerging after a one-year cycle. ▸ Extension of life cycle in association with prolonged dormancy is likely a bet-hedging strategy.