Sublethal effects of subzero temperatures on the light brown apple moth, Epiphyas postvittana: fitness costs in response to partial freezing

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2 Scopus citations


Population responses to environmental extremes often dictate the bounds to species’ distributions. However, population dynamics at, or near, those range limits may also be affected by sublethal effects. We exposed late instars and pupae of an invasive leafroller, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), to cold temperatures and measured the effects of exposure on subsequent survivorship, development, and reproduction. Cold temperature was applied as acute exposure to –10 °C (a low, but not immediately lethal temperature for this species) or the onset of freezing (the peak of the supercooling point exotherm). Survival was defined as the ability to successfully eclose as an adult. We measured immature development times, pupal mass, and adult longevity as proxies of fitness in survivors. Additionally, surviving insects were mated with individuals that had not been exposed to cold to measure fertility. There was no difference between the proportion of larvae or pupae that survived acute exposure to –10 °C and those exposed to the control temperature. Approximately 17% of larvae and 8% of pupae survived brief periods with internal ice formation and continued development to become reproductively viable adults. Importantly, surviving the onset of freezing came with significant fitness costs but not to exposure to –10 °C; most insects that survived partial freezing had lower fertility and shorter adult lifespans than either the –10 °C or control group. These results are discussed within the context of forecasting invasive insect distributions.

Original languageEnglish (US)
Pages (from-to)311-321
Number of pages11
JournalInsect Science
Issue number2
StatePublished - Apr 2019

Bibliographical note

Funding Information:
This research was supported by the National Science Foundation-Integrative Graduate Education and Research Traineeship on Introduced Species and Genotypes program at the University of Minnesota (DGE-0653827) and the US Department of Agriculture-Forest Service. We thank Dr. N. Caruthers (USDA-APHIS) for providing insect egg masses and the MAES-MDA Biosafety Level 2 staff for quarantine facility support. We also thank L. Mosca, A. Sloane, and K. Friedrich for assisting with colony maintenance and data collection. Dr. L. Bürgi and three anonymous reviewers provided helpful comments on an earlier draft.

Publisher Copyright:
© 2017 Institute of Zoology, Chinese Academy of Sciences


  • fertility
  • invasive species
  • partial freeze tolerance
  • supercooling point


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