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Spiroplasma bacteria enhance survival of Drosophila hydei attacked by the parasitic wasp Leptopilina heterotoma.

Xie J, Vilchez I, Mateos M - PLoS ONE (2010)

Bottom Line: Survival was significantly greater for Spiroplasma-infected flies, and the effect of Spiroplasma infection was most evident during the host's pupal stage.The number of wasp eggs per fly larva did not differ significantly between Spiroplasma-free and Spiroplasma-infected fly larvae, suggesting that differential fly survival is due to a post-oviposition mechanism.Our results suggest that Spiroplasma confers protection to D. hydei against wasp parasitism.

View Article: PubMed Central - PubMed

Affiliation: Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, USA.

ABSTRACT

Background: Maternally-transmitted associations between endosymbiotic bacteria and insects are ubiquitous. While many of these associations are obligate and mutually beneficial, many are facultative, and the mechanism(s) by which these microbes persist in their host lineages remain elusive. Inherited microbes with imperfect transmission are expected to be lost from their host lineages if no other mechanisms increase their persistence (i.e., host reproductive manipulation and/or fitness benefits to host). Indeed numerous facultative heritable endosymbionts are reproductive manipulators. Nevertheless, many do not manipulate reproduction, so they are expected to confer fitness benefits to their hosts, as has been shown in several studies that report defense against natural enemies, tolerance to environmental stress, and increased fecundity.

Methodology/principal findings: We examined whether larval to adult survival of Drosophila hydei against attack by a common parasitoid wasp (Leptopilina heterotoma), differed between uninfected flies and flies that were artificially infected with Spiroplasma, a heritable endosymbiont of Drosophila hydei that does not appear to manipulate host reproduction. Survival was significantly greater for Spiroplasma-infected flies, and the effect of Spiroplasma infection was most evident during the host's pupal stage. We examined whether or not increased survival of Spiroplasma-infected flies was due to reduced oviposition by the wasp (i.e., pre-oviposition mechanism). The number of wasp eggs per fly larva did not differ significantly between Spiroplasma-free and Spiroplasma-infected fly larvae, suggesting that differential fly survival is due to a post-oviposition mechanism.

Conclusions/significance: Our results suggest that Spiroplasma confers protection to D. hydei against wasp parasitism. This is to our knowledge the first report of a potential defensive mutualism in the genus Spiroplasma. Whether it explains the persistence and high abundance of this strain in natural populations of D. hydei, as well as the widespread distribution of heritable Spiroplasma in Drosophila and other arthropods, remains to be investigated.

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Related in: MedlinePlus

Wasp oviposition frequency in Spiroplasma-free and Spiroplasma-infected Drosophila hydei larvae.Proportion of fly larvae that had at least one wasp egg. Numbers above columns  =  exact proportion. Numbers in columns  =  number of fly larvae examined.
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pone-0012149-g003: Wasp oviposition frequency in Spiroplasma-free and Spiroplasma-infected Drosophila hydei larvae.Proportion of fly larvae that had at least one wasp egg. Numbers above columns  =  exact proportion. Numbers in columns  =  number of fly larvae examined.

Mentions: Our fly and wasp survival measures suggest that Spiroplasma infection confers protection to D. hydei against wasp-induced mortality, and that this effect is not detectable before the fly pupal stage. Nevertheless, we tested whether this protective effect could be also mediated by a pre-oviposition mechanism, in which Spiroplasma-infected larvae suffer significantly fewer ovipositions than their Spiroplasma-free counterparts. The number of wasp eggs found per fly larva did not differ significantly between Spiroplasma-free and Spiroplasma-infected treatments, for either the GzLMM with Poisson distribution (F(1,112)  = 0.89; P = 0.3476) or the GzLMM with a binary distribution (i.e., one or more wasp eggs grouped into a single category: F(1,112)  = 0.40, P = 0.5248; see Fig. 3). No significant effects of fly strain or vial were detected. These results suggest that Spiroplasma infection does not protect fly larvae from wasp oviposition attacks.


Spiroplasma bacteria enhance survival of Drosophila hydei attacked by the parasitic wasp Leptopilina heterotoma.

Xie J, Vilchez I, Mateos M - PLoS ONE (2010)

Wasp oviposition frequency in Spiroplasma-free and Spiroplasma-infected Drosophila hydei larvae.Proportion of fly larvae that had at least one wasp egg. Numbers above columns  =  exact proportion. Numbers in columns  =  number of fly larvae examined.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2921349&req=5

pone-0012149-g003: Wasp oviposition frequency in Spiroplasma-free and Spiroplasma-infected Drosophila hydei larvae.Proportion of fly larvae that had at least one wasp egg. Numbers above columns  =  exact proportion. Numbers in columns  =  number of fly larvae examined.
Mentions: Our fly and wasp survival measures suggest that Spiroplasma infection confers protection to D. hydei against wasp-induced mortality, and that this effect is not detectable before the fly pupal stage. Nevertheless, we tested whether this protective effect could be also mediated by a pre-oviposition mechanism, in which Spiroplasma-infected larvae suffer significantly fewer ovipositions than their Spiroplasma-free counterparts. The number of wasp eggs found per fly larva did not differ significantly between Spiroplasma-free and Spiroplasma-infected treatments, for either the GzLMM with Poisson distribution (F(1,112)  = 0.89; P = 0.3476) or the GzLMM with a binary distribution (i.e., one or more wasp eggs grouped into a single category: F(1,112)  = 0.40, P = 0.5248; see Fig. 3). No significant effects of fly strain or vial were detected. These results suggest that Spiroplasma infection does not protect fly larvae from wasp oviposition attacks.

Bottom Line: Survival was significantly greater for Spiroplasma-infected flies, and the effect of Spiroplasma infection was most evident during the host's pupal stage.The number of wasp eggs per fly larva did not differ significantly between Spiroplasma-free and Spiroplasma-infected fly larvae, suggesting that differential fly survival is due to a post-oviposition mechanism.Our results suggest that Spiroplasma confers protection to D. hydei against wasp parasitism.

View Article: PubMed Central - PubMed

Affiliation: Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, USA.

ABSTRACT

Background: Maternally-transmitted associations between endosymbiotic bacteria and insects are ubiquitous. While many of these associations are obligate and mutually beneficial, many are facultative, and the mechanism(s) by which these microbes persist in their host lineages remain elusive. Inherited microbes with imperfect transmission are expected to be lost from their host lineages if no other mechanisms increase their persistence (i.e., host reproductive manipulation and/or fitness benefits to host). Indeed numerous facultative heritable endosymbionts are reproductive manipulators. Nevertheless, many do not manipulate reproduction, so they are expected to confer fitness benefits to their hosts, as has been shown in several studies that report defense against natural enemies, tolerance to environmental stress, and increased fecundity.

Methodology/principal findings: We examined whether larval to adult survival of Drosophila hydei against attack by a common parasitoid wasp (Leptopilina heterotoma), differed between uninfected flies and flies that were artificially infected with Spiroplasma, a heritable endosymbiont of Drosophila hydei that does not appear to manipulate host reproduction. Survival was significantly greater for Spiroplasma-infected flies, and the effect of Spiroplasma infection was most evident during the host's pupal stage. We examined whether or not increased survival of Spiroplasma-infected flies was due to reduced oviposition by the wasp (i.e., pre-oviposition mechanism). The number of wasp eggs per fly larva did not differ significantly between Spiroplasma-free and Spiroplasma-infected fly larvae, suggesting that differential fly survival is due to a post-oviposition mechanism.

Conclusions/significance: Our results suggest that Spiroplasma confers protection to D. hydei against wasp parasitism. This is to our knowledge the first report of a potential defensive mutualism in the genus Spiroplasma. Whether it explains the persistence and high abundance of this strain in natural populations of D. hydei, as well as the widespread distribution of heritable Spiroplasma in Drosophila and other arthropods, remains to be investigated.

Show MeSH
Related in: MedlinePlus