Abstract Bacterial endosymbionts manipulate reproduction in arthropods to increase their prevalence in the host population. One such manipulation is cytoplasmic incompatibility (CI), wherein the bacteria sabotage sperm in infected males to reduce the hatch rate when mated with uninfected females, but zygotes are ‘rescued’ when that male mates with an infected female. In the spiderMermessus fradeorum(Linyphiidae),Rickettsiellasymbionts cause variable levels of CI. We hypothesised that temperature affects the strength of CI and its rescue inM. fradeorum, potentially mediated by bacterial titre. We rearedRickettsiella‐infected spiders in two temperature conditions (26°C vs. 20°C) and tested CI induction in males and rescue in females. In incompatible crosses between infected males and uninfected females, the hatch rate from warm males was doubled (mean ± standard error = 0.687 ± 0.052) relative to cool males (0.348 ± 0.046), indicating that CI induction is weaker in warm males. In rescue crosses between infected females and infected males, female rearing temperature had a marginal effect on CI rescue, but the hatch rate remained high for both warm (0.960 ± 0.023) and cool females (0.994 ± 0.004). Bacterial titre, as measured by quantitative polymerase chain reaction, was lower in warm than cool spiders, particularly in females, suggesting that bacterial titre may play a role in causing the temperature‐mediated changes in CI.
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The saboteur’s tools: Common mechanistic themes across manipulative symbioses.
Insects and other arthropods often harbour intracellular bacterial associates. These bacterial symbionts cannot survive outside their host and rely on vertical transmission from infected mothers to their progeny. Thus, symbiont success is tied directly to reproductive success of female hosts. As a result of this intimate relationship, these heritable symbionts have evolved numerous strategies to increase the likelihood of their own transmission, some of which involve the direct manipulation of host reproduction to increase production or fitness of female progeny. These manipulations often come at the expense of male hosts or uninfected individuals, and include strategies such as inducing crossing incompatibilities that increase infected female fitness relative to uninfected females (cytoplasmic incompatibility), killing or feminizing male hosts, and inducing asexual production of female progeny (parthenogenesis). In the past decade, there has been substantial interest in the applied use of these manipulative bacteria in control of pest species, including suppressing disease carried by mosquito vectors of human pathogens. This, along with developments in molecular tools and techniques, has spurred major advances in understanding the mechanisms by which symbiont lineages manipulate their insect hosts, culminating with the identification of the bacterial genes responsible for key manipulations. Here, we review the major research advances in the mechanisms of symbiont-induced reproductive manipulation and compare the mechanisms of a number of common reproductive manipulators.
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- Award ID(s):
- 2002934
- PAR ID:
- 10230192
- Editor(s):
- Oliver, K.M.; Russell, J.A.
- Date Published:
- Journal Name:
- Advances in insect physiology
- Volume:
- 58
- ISSN:
- 2213-6800
- Page Range / eLocation ID:
- 317-353
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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