Trade-offs between Winter Survival and Reproduction in Female Insects

Introduction to the Symposium: An Integrative Look at Whole-organism Trade-offs from the Female-centered Perspective of Biology

Trade-offs during reproduction have long been a central focus within biology and much of the foundational work within life history evolution has focused on females, as the fitness of females is more easily quantified for use in theoretical models. However, in many regards, the field of organismal biology has deviated from this early focus on females, particularly as it relates to the nuances and dynamic nature of female reproduction. Regardless, at the organismal level, reproduction is thought to trade-off with other simultaneously occurring processes. Recent papers have sought to outline the issues with our current understanding of whole-organism trade-offs, though the field as a whole has not come to a consensus on what trade-offs mean to a reproducing female. To rectify this important gap in how trade-offs are discussed in organismal biology as well as confusion about what constitutes a trade-off, our overarching goal of this symposium was to discuss trade-offs from an integrative perspective that places female reproduction at the center. By answering what trade-offs are and what they mean to reproducing females, what has been neglected in the context of whole-organism physiology, and how maternal effects fit within this framework, our group of speakers and their associated papers will crystalize nuances of measuring and determining presence (if any) of trade-offs in reproducing females in a range of taxa and subfields.

Light pollution disrupts seasonal reproductive phenotypes and reduces lifespan in the West Nile vector, Culex pipiens

Females of the Northern House mosquito, Culex pipiens, are important disease vectors as they transmit pathogens including West Nile virus. These females survive the winter by entering diapause, a state of dormancy, characterized by the accumulation of lipids, cessation of blood-feeding, and reproductive arrest. Diapause is cued by photoperiod, so as days become short in late summer and early fall, female Cx. pipiens prepare to overwinter and disease transmission decreases. We previously demonstrated that Artificial light at night (ALAN) causes female Cx. pipiens to avert diapause and continue to blood-feed when reared under short-day conditions. Additionally, light pollution alters seasonal differences in mosquito activity and nutrient reserves. However, it is unclear how exposure to ALAN affects blood-feeding and fecundity in long-day reared females, as well as the survival of Cx. pipiens exposed under both short and long-day conditions. In this study, we hypothesized that females exposed to ALAN in long-day conditions would have a lower proclivity to blood-feed, reduced fecundity, and reduced survival. Results from our lab-based experiments demonstrate that females exposed to ALAN in long-day conditions were less likely to blood-feed but were more fecund than long-day reared females that were not exposed to ALAN, and that ALAN exposure did not affect lifespan of long-day reared females. Additionally, we hypothesized ALAN exposure under short-day conditions would reduce survival, and our data supports this hypothesis. Overall, our results demonstrate that ALAN is an important urban stressor that has the potential to affect reproduction and lifespan in mosquitoes, and therefore has the potential to create evolutionary tradeoffs.