Extreme heat alters the performance of hosts and pathogen

The frequency and intensity of extreme heat in the environment have increased last decade. Extreme heating events (EHE) wide-ranging impacts on biological systems from molecular to community level. However, EHE been poorly studied pathogen–host systems. Here, we explore how affects interaction among insect hosts, Osmia cornifrons lignaria , a protozoan pathogen, Crithidia mellificae . We compared changes upper limit for locomotion hosts (Ct max ), thermal boldness (voluntary exposure Temperature Zones – ETZ) between healthy infected host exposed EHE, effect Ct pathogen growth rate. Our results showed that 1-day significantly reduced by an average 4 °C 7 hosts. Further, also hosts’ voluntary (or transit across) (hot or cold) temperature zones (ETZ). show reduces both tolerance fitness, shed light implications host–pathogen dynamics under warmer world.