Heatwaves cause relative fitness decline in aquatic insects by altering life history and host–pathogen relationships

• DOI: 10.1002/ecs2.70241
• Publication Date: 2025-04-11T02:05:56Z
• Authors: Sarah A. Taig; Galen Holt; Georgia K. Dwyer; Rebecca E. Lester
• Keywords: Life History Theory

Abstract Extreme climatic events are linked to an increase in emergent diseases. Such increases depend on the relationships between environmental conditions and host–parasite dynamics. Caddisflies host oomycete Saprolegnia , which has increased prevalence freshwater systems causes mortality caddisflies, most prominently Ulmerochorema rubiconum . We tested how short (12 h) or longer (21 days) heatwaves (22.5°C water temperature) alter U. hatching infection eggs compared no heatwave (i.e., ongoing low temperatures at 12.5°C). Short yielded similarly elevated probability heatwaves. A shortened egg period significantly a As resulted durations than heatwaves, they could pose greater risk caddisfly populations Population modeling demonstrates this hatching‐infection trade‐off determines effect of population growth rates. Predicted frequency magnitude likelihood that would experience favorable for infection, potentially disrupting ecosystem functioning. Similar asymmetric impacts climate ecological likely common may yield important outcomes. The responses hosts pathogens change must be studied unison, rather individual components isolation.