Robbing insects of sex? Testing for a correlation between Wolbachia and asexual reproduction in Adelgidae (Sternorrhyncha: Aphidoidea)

Sexual reproduction confers many advantages over asexual reproduction, such as genetic recombination to enhance genetic diversity, and removal of deleterious mutations. However, despite these advantages, many species across Insecta exhibit asexual reproduction. The mechanisms of asexuality are varied among insects, but one cause is through the influence of facultative, bacterial, endosymbionts. A great example of this is Wolbachia, notorious for inducing male killing, cytoplasmic incompatibility, and inducing parthenogenesis in insects. Wolbachia are ubiquitous among insects, where they may confer fitness advantages and/or be self-serving. While primarily researched in Holometabola, Wolbachia are found in other groups also, such as Sternorrhyncha. Adelgidae are sternorrhynchans that feed on conifers. Like many other sap feeders, adelgids are known to harbor obligate endosymbionts, which provide nutritional supplementation. However, facultative symbionts have yet to be reported from this group. Notably, asexuality is common in adelgids, despite the negative effect it may have on long-term lineage fitness. We have recently detected Wolbachia in an asexual species of adelgid. We therefore hypothesized that Wolbachia may contribute to the loss of sexual generations in some adelgid species and populations. As a first step in testing this concept, we determined which adelgid species and populations harbor Wolbachia, then performed a correlational analysis to establish whether or not a relationship exists between the presence of Wolbachia and asexual reproduction of adelgids.