Wolbachia strains for disease control: ecological and evolutionary considerations

Abstract

Wolbachia are endosymbionts found in many insects with the potential to suppress vectorborne diseases, particularly through interfering with pathogen transmission. Wolbachia strains are highly variable in their effects on hosts, raising the issue of which attributes should be selected to ensure that the best strains are developed for disease control. This depends on their ability to suppress viral transmission, invade host populations, persist without loss of viral suppression and not interfere with other control strategies. The potential to achieve these objectives is likely to involve evolutionary constraints; viral suppression may be limited by the ability of infections to spread due to deleterious host fitness effects. However, there are exceptions to these patterns in both natural infections and in novel associations generated following interspecific transfer, suggesting that pathogen blockage, deleterious fitness effects and changes to reproductive biology might be at least partly decoupled to achieve ideal infection attributes. The stability of introduced Wolbachia and its effects on viral transmission remain unclear, but rapid evolutionary changes seem unlikely. Although deliberate transfers of Wolbachia across species remain particularly challenging, the availability of strains with desirable attributes should be expanded, taking advantage of the diversity available across thousands of strains in natural populations.

Mosquito vector‐associated microbiota: Metabarcoding bacteria and eukaryotic symbionts across habitat types in Thailand endemic for dengue and other arthropod‐borne diseases

“…In the former case, dengue virus is blocked in experimentally transfected Ae. aegypti with wMel and wMelPop strains of Wolbachia (Hoffmann, Ross, & Rai, 2015): These mosquitoes are being released to suppress dengue transmission (Frentiu et al., 2014). In the latter case, experimentally transfected Ae.…”

Incidence of Wolbachia in aquatic insects

“…As a result, introducing an infection within one species, especially an invasive species, may not pose a serious risk (Dobson, Bordenstein, & Rose, 2016). However, different strains of Wolbachia will pose different risks to the hosts (Hoffmann, Ross, & Rašić, 2015; Ritchie, Townsend, Paton, Callahan, & Hoffmann, 2015). Releasing a virulent strain into the environment that can interfere with reproduction with the intended consequence of reducing abundance of one insect species may carry unintended consequences for nontarget taxa.…”

Unique clade of alphaproteobacterial endosymbionts induces complete cytoplasmic incompatibility in the coconut beetle

“…To assess the potential of this endosymbiont as a biological control agent, we intend to investigate the effects of such elimination on total egg production and longevity, as well as the effects of transinfection with these endosymbionts on fecundity. Finally, Wolbachia infection may suppress the transmission of pathogens to humans by mosquitoes, including dengue, malaria, and zika, along with plant diseases transmitted by planthoppers (33). Further investigation may reveal that the endosymbiont of B. longissima has such effects on pathogen transmission as well.…”