Comparative analysis ofWolbachiamaternal transmission and localization in host ovaries

Abstract

Many insects and other animals carry microbial endosymbionts that influence their reproduction and fitness. These relationships only persist if endosymbionts are reliably transmitted from one host generation to the next.Wolbachiaare maternally transmitted endosymbionts found in most insect species, but transmission rates can vary across environments. Maternal transmission ofwMelWolbachiadepends on temperature in naturalDrosophila melanogasterhosts and in transinfectedAedes aegypti, wherewMel is used to block pathogens that cause human disease. InD. melanogaster,wMel transmission declines in the cold asWolbachiabecome less abundant in host ovaries and at the posterior pole plasm (the site of germline formation) in mature oocytes. Here, we assess how temperature affects maternal transmission and underlying patterns ofWolbachialocalization across 10Wolbachiastrains diverged up to 50 million years—including strains closely related towMel—and their naturalDrosophilahosts. ManyWolbachiamaintain high transmission rates across temperatures, despite highly variable (and sometimes low) levels ofWolbachiain the ovaries and at the developing germline in late-stage oocytes. Identifying strains like closely relatedwMel-likeWolbachiawith stable transmission across variable environmental conditions may improve the efficacy ofWolbachia-based biocontrol efforts as they expand into globally diverse environments.