PT - JOURNAL ARTICLE AU - J. Charlesworth AU - L. A. Weinert AU - E. V. Araujo-Jnr. AU - J. J. Welch TI - <em>Wolbachia, Cardinium</em> and climate: an analysis of global data AID - 10.1101/490284 DP - 2018 Jan 01 TA - bioRxiv PG - 490284 4099 - http://biorxiv.org/content/early/2018/12/08/490284.short 4100 - http://biorxiv.org/content/early/2018/12/08/490284.full AB - Bacterial secondary symbionts are very common in terrestrial arthropods, but infection levels vary widely among populations. Experiments and within-species comparisons both suggest that environmental temperature might be important in explaining this variation. To investigate the importance of temperature, at broad geographical and taxonomic scales, we extended a global database of terrestrial arthropods screened for Wolbachia and Cardinium. Our final data set contained data from 114,297 arthropods (&gt;2,500 species) screened for Wolbachia and 17,011 arthropods (&gt;800 species) screened for Cardinium, including population samples from 137 different countries, and with mean temperatures varying from - 6.5 to 29.2°C. In insects and relatives, Cardinium infection showed a clear and consistent tendency to increase with temperature. For Wolbachia, a tendency to increase with temperature in temperate climates, is counteracted by reduced prevalence in the tropics, resulting in a weak negative trend overall. We discuss the implications of these results for natural and introduced symbionts, in regions affected by climate change.