Pervasive Effects of on Host Temperature Preference.

Heritable symbionts can modify a range of ecologically important host traits, including behavior. About half of all insect species are infected with maternally transmitted , a bacterial endosymbiont known to alter host reproduction, nutrient acquisition, and virus susceptibility. Here, we broadly test the hypothesis that modifies host behavior by assessing the effects of eight different strains on the temperature preference of six subgroup species. Four of the seven host genotypes infected with A-group strains (Ri in , Ha in , Sh in , and Tei in ) prefer significantly cooler temperatures relative to uninfected genotypes. Contrastingly, when infected with divergent B-group Mau, prefers a warmer temperature. For most strains, changes to host temperature preference do not alter titer. However, males infected with Sh and Tei tend to experience an increase in titer when shifted to a cooler temperature for 24 h, suggesting that -induced changes to host behavior may promote bacterial replication. Our results indicate that modifications to host temperature preference are likely widespread, which has important implications for insect thermoregulation and physiology. Understanding the fitness consequences of these effects is crucial for predicting evolutionary outcomes of host-symbiont interactions, including how spreads to become common. Microbes infect a diversity of species, influencing the performance and fitness of their hosts. Maternally transmitted bacteria infect most insects and other arthropods, making these bacteria some of the most common endosymbionts in nature. Despite their global prevalence, it remains mostly unknown how influence host physiology and behavior to proliferate. We demonstrate pervasive effects of on temperature preference. Most hosts infected with A-group prefer cooler temperatures, whereas the one host species infected with divergent B-group prefers warmer temperatures, relative to uninfected genotypes. Changes to host temperature preference generally do not alter abundance in host tissues, but for some A-group strains, adult males have increased titer when shifted to a cooler temperature. This suggests that -induced changes to host behavior may promote bacterial replication. Our results help elucidate the impact of endosymbionts on their hosts amid the global pandemic.