Host Defence: Getting By with a Little Help from Our Friends

Hurst, Gregory D. D.; Hutchence, Kate J.

doi:10.1016/j.cub.2010.07.038

Cited by 20 publications

(22 citation statements)

References 17 publications

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“…The range of phenotypic effects that viral endosymbionts have on their hosts is poorly understood. For example, to what extent do viral endosymbionts act as mutualists by providing benefits to the host as has been found with bacterial endosymbionts [7]? Viruses have been shown to be capable of such phenotypes [10]; for example, polydnaviruses preventing the larvae of parasitoid wasps from being encapsulated in their host.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, the pure maternal transmission seen in bacterial endosymbionts does not by itself allow an endosymbiont to spread, as if the infection is at all costly to its host it will lead to a parasite's decline and extinction [51,52]. This has led bacterial endosymbionts to evolve elaborate strategies to enhance their transmission to future generations that range from providing benefits to the host to manipulation of host reproduction-such as causing cytoplasmic incompatibilities between infected and uninfected individuals or distorting the sex ratio towards females [2,5,7].…”

Section: Population Dynamics and The Cost Of Infectionmentioning

confidence: 99%

“…For example, symbionts can protect insects against natural enemies [7], allow them to feed on particular plants [2], distort the sex ratio to such an extent that sexual behaviour changes [8] and potentially promote speciation by inducing reproductive incompatibilities [9]. In other taxa viral endosymbionts can have important consequences for their hosts.…”

Section: Introductionmentioning

confidence: 99%

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Vertically transmitted viral endosymbionts of insects: do sigma viruses walk alone?

Longdon

Jiggins

2012

Proc. R. Soc. B.

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Insects are host to a wide range of vertically transmitted bacterial endosymbionts, but we know relatively little about their viral counterparts. Here, we discuss the vertically transmitted viral endosymbionts of insects, firstly examining the diversity of this group, and then focusing on the well-studied sigma viruses that infect dipterans. Despite limited sampling, evidence suggests that vertically transmitted viruses may be common in insects. Unlike bacteria, viruses can be transmitted through sperm and eggs, a trait that allows them to rapidly spread through host populations even when infection is costly to the host. Work on Drosophila melanogaster has shown that sigma viruses and their hosts are engaged in a coevolutionary arms race, in which the spread of resistance genes in the host population is followed by the spread of viral genotypes that can overcome host resistance. In the long-term, associations between sigma viruses and their hosts are unstable, and the viruses persist by occasionally switching to new host species. It therefore seems likely that viral endosymbionts have major impacts on the evolution and ecology of insects.

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Section: Discussionmentioning

confidence: 99%

Section: Population Dynamics and The Cost Of Infectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vertically transmitted viral endosymbionts of insects: do sigma viruses walk alone?

Longdon

Jiggins

2012

Proc. R. Soc. B.

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“…Unlike obligate symbionts, they are not essential for successful growth and reproduction and they persist either by manipulating host reproduction for their own benefit [2] or because they confer some fitness advantage on their host. Symbionts have been shown to help their hosts resist abiotic challenges and attack by natural enemies [3][4][5]. The importance of facultative symbionts has become increasingly apparent in the last two decades yet we still know relatively little about how they affect their hosts' interactions in complex food webs.…”

Section: Introductionmentioning

confidence: 99%

Evidence for specificity in symbiont-conferred protection against parasitoids

2015

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Many insects harbour facultative symbiotic bacteria, some of which have been shown to provide resistance against natural enemies. One of the best-known protective symbionts is Hamiltonella defensa, which in pea aphid (Acyrthosiphon pisum) confers resistance against attack by parasitoid wasps in the genus Aphidius (Braconidae). We asked (i) whether this symbiont also confers protection against a phylogenetically distant group of parasitoids (Aphelinidae) and (ii) whether there are consistent differences in the effects of bacteria found in pea aphid biotypes adapted to different host plants. We found that some H. defensa strains do provide protection against an aphelinid parasitoid Aphelinus abdominalis. Hamiltonella defensa from the Lotus biotype provided high resistance to A. abdominalis and moderate to low resistance to Aphidius ervi, while the reverse was seen from Medicago biotype isolates. Aphids from Ononis showed no evidence of symbiont-mediated protection against either wasp species and were relatively vulnerable to both. Our results may reflect the different selection pressures exerted by the parasitoid community on aphids feeding on different host plants, and could help explain the maintenance of genetic diversity in bacterial symbionts.

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“…Several recent studies have reported facultative symbionts that confer protection to their host against parasites and pathogens (Hurst and Hutchence, 2010). Several bacterial symbionts of aphids confer protection against parasitoid wasps (Oliver et al, 2003(Oliver et al, , 2005Vorburger et al, 2009) and fungi (Scarborough et al, 2005;Lukasik et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Male killing Spiroplasma protects Drosophila melanogaster against two parasitoid wasps

et al. 2013

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Maternally transmitted associations between endosymbiotic bacteria and insects are diverse and widespread in nature. Owing to imperfect vertical transmission, many heritable microbes have evolved compensational mechanisms to enhance their persistence in host lineages, such as manipulating host reproduction and conferring fitness benefits to host. Symbiont-mediated defense against natural enemies of hosts is increasingly recognized as an important mechanism by which endosymbionts enhance host fitness. Members of the genus Spiroplasma associated with distantly related Drosophila hosts are known to engage in either reproductive parasitism (i.e., male killing) or defense against natural enemies (the parasitic wasp Leptopilina heterotoma and a nematode). A male-killing strain of Spiroplasma (strain Melanogaster Sex Ratio Organism (MSRO)) co-occurs with Wolbachia (strain wMel) in certain wild populations of the model organism Drosophila melanogaster. We examined the effects of Spiroplasma MSRO and Wolbachia wMel on Drosophila survival against parasitism by two common wasps, Leptopilina heterotoma and Leptopilina boulardi, that differ in their host ranges and host evasion strategies. The results indicate that Spiroplasma MSRO prevents successful development of both wasps, and confers a small, albeit significant, increase in larva-toadult survival of flies subjected to wasp attacks. We modeled the conditions under which defense can contribute to Spiroplasma persistence. Wolbachia also confers a weak, but significant, survival advantage to flies attacked by L. heterotoma. The host protective effects exhibited by Spiroplasma and Wolbachia are additive and may provide the conditions for such cotransmitted symbionts to become mutualists. Occurrence of Spiroplasma-mediated protection against distinct parasitoids in divergent Drosophila hosts suggests a general protection mechanism.

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Host Defence: Getting By with a Little Help from Our Friends

Cited by 20 publications

References 17 publications

Vertically transmitted viral endosymbionts of insects: do sigma viruses walk alone?

Vertically transmitted viral endosymbionts of insects: do sigma viruses walk alone?

Evidence for specificity in symbiont-conferred protection against parasitoids

Male killing Spiroplasma protects Drosophila melanogaster against two parasitoid wasps

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