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Male Feminization of the Common Pillbug Armadillidium vulgare by Wolbachia bacteria

Ramanan et al. | Jun 30, 2024

Male Feminization of the Common Pillbug <i>Armadillidium vulgare</i> by <i>Wolbachia</i> bacteria
Image credit: Ramanan et al. 2024

Wolbachia pipientis (Wolbachia) is a maternally inherited endosymbiotic bacterium that infects over 50% of arthropods, including pillbugs, and acts as a reproductive parasite in the host. In the common terrestrial pillbug Armadillidium vulgare (A. vulgare), Wolbachia alters the sex ratio of offspring through a phenomenon called feminization, where genetic males develop into reproductive females. Previous studies have focused on the presence or absence of Wolbachia as a sex ratio distorter in laboratory cultured and natural populations mainly from sites in Europe and Japan. Our three-year study is the first to evaluate the effects of the Wolbachia sex ratio distorter in cultured A. vulgare offspring in North America. We asked whether Wolbachia bacteria feminize A. vulgare isopod male offspring from infected mothers and if this effect can be detected in F1 offspring by comparing the male/female offspring ratios. If so, the F1 offspring ratio should show a higher number of females than males compared to the offspring of uninfected mothers. Over three years, pillbug offspring were cultured from pregnant A. vulgare females and developed into adults. We determined the Wolbachia status of mothers and counted the ratios of male and female F1 progeny to determine feminization effects. In each year sampled, significantly more female offspring were born to Wolbachia-infected mothers than those from uninfected mothers. These ratio differences suggest that the Wolbachia infection status of mothers directly impacts the A. vulgare population through the production of reproductive feminized males, which in turn provides an advantage for further Wolbachia transmission.

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The presence of Wolbachia in Brood X cicadas

Hasan et al. | Oct 15, 2022

The presence of <em>Wolbachia</em> in Brood X cicadas

Here, seeking to understand a possible cause of the declining popluations of Brood X cicadas in Ohio and Indiana, the authors investigated the presence of Wolbachia, an inherited bacterial symbiont that lives in the reproductive cells of approximately 60% of insect species in these cicadas. Following their screening of one-hundred 17-year periodical cicadas, they only identified the presence of Wolbachia infection in less than 2%, suggesting that while Wolbachia can infect cicadas it appears uncommon in the Brood X cicadas they surveyed.

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