Positive association between the diversity of symbionts and parasitoids of aphids in field populations

Hafer-Hahmann, Nina; Vorburger, Christoph

doi:10.1002/ecs2.3355

Cited by 7 publications

(8 citation statements)

References 79 publications

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“…As a consequence, secondary symbionts tend to occur at intermediate frequencies in nature (reviewed by Guo et al., 2017 ; McLean et al., 2016 ; Oliver et al., 2014 ; Zytynska & Weisser, 2016 ). Correlations between parasitoids and the symbiont communities of their aphid hosts observed in natural populations suggest that these frequencies may be partially driven by interactions between symbionts and parasitoids (Hafer‐Hahmann & Vorburger, 2021 ; Smith et al., 2015 ). However, more experimental approaches are required to establish the causal factors underlying these associations.…”

Section: Introductionmentioning

confidence: 99%

Bottom‐up effect of host protective symbionts on parasitoid diversity: Limited evidence from two field experiments

Narayan

Vorburger

Hafer-Hahmann

2022

Journal of Animal Ecology

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Protective symbionts can provide effective and specific protection to their hosts. This protection can differ between different symbiont strains with each strain providing protection against certain components of the parasite and pathogen community their host faces. Protective symbionts are especially well known from aphids where, among other functions, they provide protection against different parasitoid wasps. However, most of the evidence for this protection comes from laboratory experiments. Our aim was to understand how consistent protection is across different symbiont strains under natural field conditions and whether symbiont diversity enhanced the species diversity of colonizing parasitoids, as could be expected from the specificity of their protection. We used experimental colonies of the black bean aphid Aphis fabae to investigate symbiont‐conferred protection under natural field conditions over two seasons. Colonies differed only in their symbiont composition, carrying either no symbionts, a single strain of the protective symbiont Hamiltonella defensa, or a mixture of three H. defensa strains. These aphid colonies were exposed to natural parasitoid communities in the field. Subsequently, we determined the parasitoids hatched from each aphid colony. The evidence for a protective effect of H. defensa was limited and inconsistent between years, and aphid colonies harbouring multiple symbiont strains did not support a more diverse parasitoid community. Instead, parasitoid diversity tended to be highest in the absence of H. defensa. Symbiont‐conferred protection, although a strong and repeatable effect under laboratory conditions may not always cause the predicted bottom‐up effects under natural conditions in the field.

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Section: Introductionmentioning

confidence: 99%

Bottom‐up effect of host protective symbionts on parasitoid diversity: Limited evidence from two field experiments

Narayan

Vorburger

Hafer-Hahmann

2022

Journal of Animal Ecology

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“…In a diverse plant community, with higher natural enemy diversity (including various parasitoid wasp species, entomopathogenic fungi and generalist predators), then there may be no single optimal symbiont combination. In this case, variable costs and benefits of co-hosting multiple symbionts could lead to aphids hosting various combinations of the available symbionts (higher diversity) (Hafer-Hahmann & Vorburger 2021). The idea is that with a greater variety of natural enemies each aphid hosts a different symbiont combination but is not protected against all attackers.…”

Section: Introductionmentioning

confidence: 99%

Floral presence and flower identity alter cereal aphid endosymbiont communities on adjacent crops

Zytynska

Sturm

Hawes

et al. 2023

Preprint

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1. Floral plantings adjacent to crops fields can recruit populations of natural enemies by providing flower nectar and non-crop prey to increase natural pest regulation. Observed variation in success rates might be due to changes in the unseen community of protective endosymbionts hosted by many herbivorous insects, which can confer resistance to various specialist natural enemies, e.g. parasitoid wasps. Reduced insect control may occur if highly protective symbiont combinations increase in frequency via selection effects, and this is expected to be stronger in lower diversity systems. 2. We used a large-scale field trial to analyse the bacterial endosymbiont communities hosted by cereal aphids (Sitobion avenae) collected along transects into strip plots of barley plants managed by either conventional or integrated (including floral field margins and reduced inputs) methods. In addition, we conducted an outdoor pot experiment to analyse endosymbionts in S. avenae aphids collected on barley plants that were either grown alone or alongside one of three flowering plants, across three time points. 3. In the field, aphids hosted up to four symbionts. The abundance of aphids and parasitoid wasps was reduced towards the middle of all fields while aphid symbiont species richness and diversity decreased into the field in conventional, but not integrated, field-strips. The proportion of aphids hosting different symbiont combinations varied across cropping systems, with distances into the fields, and were correlated with parasitoid wasp abundances. 4. In the pot experiment, aphids hosted up to six symbionts. Flower presence increased natural enemy abundance and diversity, and decreased aphid abundance. The proportion of aphids hosting different symbiont combinations varied across the flower treatment and time, and were correlated with varying abundances of the different specialist parasitoid wasp species recruited by different flowers. 5. Synthesis and applications. Floral plantings and flower identity can have community-wide impacts on the combinations of bacterial endosymbionts hosted by herbivorous insects. Our work highlights the potential of within-season selection for symbiont-mediated pest resistance to natural enemies with biological control impacts. This could be mitigated through increased recruitment of diverse natural enemies by incorporating functional diversity of floral resources into the environment.

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“…Here, we conducted a field study on four congeneric aphid species (Aphis fabae fabae, Aphis hederae, Aphis ruborum, and Aphis urticata), all occurring in the same ruderal habitats (albeit on different host plants), and all potentially harboring the same secondary symbionts. Furthermore, all four aphid species are attacked by the same dominant parasitoid wasp species, Lysiphlebus fabarum (Starý, 2006;Hafer-Hahmann and Vorburger, 2021), although the genetic structure of this species shows significant host-associated genetic differentiation indicative of some degree of host specialization or host fidelity (Sandrock et al, 2011). We measured the natural infection rate for six of the most common symbionts, and we investigated the strain diversity in one of those symbionts, H. defensa, which provides strong protection against L. fabarum (e.g., Schmid et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Gated Communities: Inter- and Intraspecific Diversity of Endosymbionts Across Four Sympatric Aphid Species

2022

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Aphids have evolved tight relationships with heritable endosymbionts, i.e., bacteria hosted within their tissues. Besides the primary endosymbiont Buchnera aphidicola, aphids host many facultative secondary endosymbionts with functions they may or may not benefit from. The different phenologies, lifestyles, and natural enemies of aphid species are predicted to favor the selection for distinct endosymbiont assemblages, as well as the emergence of intra-specific genetic diversity in the symbiotic bacteria. In this study, we (1) investigated the diversity of endosymbionts associated with four species from the genus Aphis in the field, and (2) we characterized the genetic diversity of Hamiltonella defensa, an endosymbiont that protects aphids against parasitoid wasps. We observed strong differences in the composition of endosymbiont communities among the four aphid species. H. defensa was clearly the dominant symbiont, although its abundance in each species varied from 25 to 96%. Using a multilocus sequence-typing approach, we found limited strain diversity in H. defensa. Each aphid species harbored two major strains, and none appeared shared between species. Symbiont phylogenies can thus help to understand the (seemingly limited) mobility of endosymbionts in aphid communities and the selection forces driving strain diversification.

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Positive association between the diversity of symbionts and parasitoids of aphids in field populations

Cited by 7 publications

References 79 publications

Bottom‐up effect of host protective symbionts on parasitoid diversity: Limited evidence from two field experiments

Bottom‐up effect of host protective symbionts on parasitoid diversity: Limited evidence from two field experiments

Floral presence and flower identity alter cereal aphid endosymbiont communities on adjacent crops

Gated Communities: Inter- and Intraspecific Diversity of Endosymbionts Across Four Sympatric Aphid Species

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