Longevity and oviposition of winter-emerging Chironomidae (Insecta: Diptera) at varying low temperatures

Abstract

Chironomidae (Diptera) are among the few insects with representatives that emerge during temperate winters; past work shows winter-emerging species are long-lived. We extend previous studies, examining the influence that varying air temperatures have on longevity and oviposition rates, and whether oviposition status impacts longevity. Adult chironomids (n = 339) were collected during winter of 2020 near a spring-fed stream in Camden State Park (Minnesota, USA). Insects were separated into 2 °C, 6 °C, and ambient outdoor (AO) temperature treatment groups to determine differential longevity and oviposition rates. Behaviours were monitored daily until death. The 2 °C group lived significantly longer than both 6 °C and AO groups, with mean longevities of 19.8, 14.9, and 13.9 days, respectively. Additionally, females held at 6 °C appear to have higher oviposition rates compared to 2 °C and AO groups. Results suggest low temperatures may delay or inhibit oviposition, suggesting a potential tradeoff of oviposition rate in favour of longevity.

Keywords:

• Chironomidae
• Diamesa
• winter emergence
• snow activity
• longevity
• cold hardiness
• winter dynamics

Acknowledgements

We thank the Biology Program at Southwest Minnesota State University for providing space and supplies to carry out this project. The associated field work was conducted with permission granted by a Parks and Trails Division Research Permit from the Minnesota Department of Natural Resources (permit number 202010). Thanks also to Dr Bruce Vondracek for reviewing an earlier version of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.