Wolbachia: master manipulators of invertebrate biology

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112

Vector‐borne diseases are a major health burden, yet factors affecting their spread are only partially understood. For example, microbial symbionts can impact mosquito reproduction, survival, and vectorial capacity, and hence affect disease transmission. Nonetheless, current knowledge of mosquito‐associated microbial communities is limited. To characterize the bacterial and eukaryotic microbial communities of multiple vector species collected from different habitat types in disease endemic areas, we employed next‐generation 454 pyrosequencing of 16S and 18S rRNA amplicon libraries, also known as metabarcoding. We investigated pooled whole adult mosquitoes of three medically important vectors, Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus, collected from different habitats across central Thailand where we previously characterized mosquito diversity. Our results indicate that diversity within the mosquito microbiota is low, with the majority of microbes assigned to one or a few taxa. Two of the most common eukaryotic and bacterial genera recovered (Ascogregarina and Wolbachia, respectively) are known mosquito endosymbionts with potentially parasitic and long evolutionary relationships with their hosts. Patterns of microbial composition and diversity appeared to differ by both vector species and habitat for a given species, although high variability between samples suggests a strong stochastic element to microbiota assembly. In general, our findings suggest that multiple factors, such as habitat condition and mosquito species identity, may influence overall microbial community composition, and thus provide a basis for further investigations into the interactions between vectors, their microbial communities, and human‐impacted landscapes that may ultimately affect vector‐borne disease risk.

Section: Discussionmentioning

confidence: 99%

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

Thongsripong

Chandler

Green

et al. 2017

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112

“…Although Wolbachia is known to influence reproductive processes in a number of arthropods (Werren et al. 2008), it is unclear what effect, if any, this symbiont may have on A. glycines . Wolbachia was undetectable in several individuals of clonal line 2, but offspring production was equivalent among clonal lines under stress.…”

Section: Discussionmentioning

confidence: 99%

Stress‐induced changes in abundance differ among obligate and facultative endosymbionts of the soybean aphid

Enders

Miller

2016

Bacterial endosymbionts can drive evolutionary novelty by conferring adaptive benefits under adverse environmental conditions. Among aphid species there is growing evidence that symbionts influence tolerance to various forms of stress. However, the extent to which stress inflicted on the aphid host has cascading effects on symbiont community dynamics remains poorly understood. Here we simultaneously quantified the effect of host‐plant induced and xenobiotic stress on soybean aphid (Aphis glycines) fitness and relative abundance of its three bacterial symbionts. Exposure to soybean defensive stress (Rag1 gene) and a neurotoxic insecticide (thiamethoxam) substantially reduced aphid composite fitness (survival × reproduction) by 74 ± 10% and 92 ± 2%, respectively, which in turn induced distinctive changes in the endosymbiont microbiota. When challenged by host‐plant defenses a 1.4‐fold reduction in abundance of the obligate symbiont Buchnera was observed across four aphid clonal lines. Among facultative symbionts of Rag1‐stressed aphids, Wolbachia abundance increased twofold and Arsenophonus decreased 1.5‐fold. A similar pattern was observed under xenobiotic stress, with Buchnera and Arsenophonus titers decreasing (1.3‐fold) and Wolbachia increasing (1.5‐fold). Furthermore, variation in aphid virulence to Rag1 was positively correlated with changes in Arsenophonus titers, but not Wolbachia or Buchnera. A single Arsenophonus multi‐locus genotype was found among aphid clonal lines, indicating strain diversity is not primarily responsible for correlated host‐symbiont stress levels. Overall, our results demonstrate the nature of aphid symbioses can significantly affect the outcome of interactions under stress and suggests general changes in the microbiome can occur across multiple stress types.

“…Wolbachia is a genus of bacteria found within the tissues of several groups of arthropods (Pietri, DeBruhl, & Sullivan, 2016; Werren, Baldo, & Clark, 2008). They typically infect the reproductive tissues of insects where they can manipulate reproduction of their hosts to enhance the vertical transmission of Wolbachia from mother to offspring (Werren et al., 2008).…”

Section: Introductionmentioning

confidence: 99%

“…They typically infect the reproductive tissues of insects where they can manipulate reproduction of their hosts to enhance the vertical transmission of Wolbachia from mother to offspring (Werren et al., 2008). Recent estimates for Wolbachia placed infection rates among arthropod species at 40%, 52%, and 66% (Hilgenboecker, Hammerstein, Schlattmann, Telschow, & Werren, 2008; Weinert, Araujo‐Jnr, Ahmed, & Welch, 2015; Zug & Hammerstein, 2012).…”

Section: Introductionmentioning

confidence: 99%

Incidence of Wolbachia in aquatic insects

Sazama

Bosch

Shouldis

et al. 2017

Wolbachia is a genus of intracellular bacteria typically found within the reproductive systems of insects that manipulates those systems of their hosts. While current estimates of Wolbachia incidence suggest that it infects approximately half of all arthropod species, these estimates are based almost entirely on terrestrial insects. No systematic survey of Wolbachia in aquatic insects has been performed. To estimate Wolbachia incidence among aquatic insect species, we combined field‐collected samples from the Missouri River (251 samples from 58 species) with a global database from previously published surveys. The final database contained 5,598 samples of 2,687 total species (228 aquatic and 2,459 terrestrial). We estimate that 52% (95% CrIs: 44%–60%) of aquatic insect species carry Wolbachia, compared to 60% (58%–63%) of terrestrial insects. Among aquatic insects, infected orders included Odonata, Coleoptera, Trichoptera, Ephemeroptera, Diptera, Hemiptera, and Plecoptera. Incidence was highest within aquatic Diptera and Hemiptera (69%), Odonata (50%), and Coleoptera (53%), and was lowest within Ephemeroptera (13%). These results indicate that Wolbachia is common among aquatic insects, but incidence varies widely across orders and is especially uncertain in those orders with low sample sizes such as Ephemeroptera, Plecoptera, and Trichoptera.