Comparative life-history responses of lacewings to changes in temperature

Abstract

Insects play a crucial role in all ecosystems, and are increasingly exposed to higher in temperature extremes under climate change, which can have substantial effects on their abundances. However, the effects of temperature on changes in abundances or population fitness are filtered through differential responses of life-history components, such as survival, reproduction, and development, to their environment. Such differential responses, or trade-offs, have been widely studied in birds and mammals, but comparative studies on insects are largely lacking, limiting our understanding of key mechanisms that may buffer or exacerbate climate-change effects across insect species. Here, we performed a systematic literature review of the ecological studies of lacewings (Neuroptera), predatory insects that play a crucial role in ecosystem pest regulation, to investigate the impact of temperature on life-cycle dynamics across species. We found quantitative information, linking stage-specific survival, development, and reproduction to temperature variation, for 64 species from 39 locations. We then used multivariate generalized mixed models to assess how much temperature accounts for the covariation in the latter life-history processes. We found that developmental times consistently decreased with temperature for all species. Survival and reproduction however showed a weaker and nonlinear response to temperature, with highest survival and reproduction at optimal temperatures of 24-27 ºC. After accounting for temperature and species-specific effects on life-history processes, the latter covaried consistently across two main axes of variation related to development and reproductive output, suggesting the presence of intrinsic life-history tradeoffs. Such tradeoffs appear to differ to the ones observed in previous life-history analyses on vertebrates because, unlike in vertebrates, higher survival to adult stages is positively associated with faster developmental times. Our work highlights the importance of comparative studies of life-history responses of insects for climate-change and comparative demographic research and points to important knowledge gaps, such as a better assessment of adult survival and dormancy.