Cowpea aphid (<i>Aphis craccivora</i>) associated with different host plants has different facultative endosymbionts

Brady, Cristina M.; White, Jennifer A.

doi:10.1111/een.12020

Cited by 96 publications

(104 citation statements)

References 25 publications

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“…craccivora is infected with the heritable facultative symbiont H. defensa, which confers protection against some species of parasitic wasps (37,38). Despite clear benefits to infection in the presence of wasps, however, this symbiont is found only at intermediate frequencies in natural populations (44,45). In this study, we identified clear costs to infection and maternal transmission failures associated with this protective symbiont, which likely constrain H. defensa spread in natural populations.…”

Section: Discussionmentioning

confidence: 75%

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Factors Limiting the Spread of the Protective Symbiont Hamiltonella defensa in Aphis craccivora Aphids

Dykstra

Weldon

Martinez

et al. 2014

Appl Environ Microbiol

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Many insects are associated with heritable symbionts that mediate ecological interactions, including host protection against natural enemies. The cowpea aphid, Aphis craccivora, is a polyphagous pest that harbors Hamiltonella defensa, which defends against parasitic wasps. Despite this protective benefit, this symbiont occurs only at intermediate frequencies in field populations. To identify factors constraining H. defensa invasion in Ap. craccivora, we estimated symbiont transmission rates, performed fitness assays, and measured infection dynamics in population cages to evaluate effects of infection. Similar to results with the pea aphid, Acyrthosiphon pisum, we found no consistent costs to infection using component fitness assays, but we did identify clear costs to infection in population cages when no enemies were present. Maternal transmission rates of H. defensa in Ap. craccivora were high (ca. 99%) but not perfect. Transmission failures and infection costs likely limit the spread of protective H. defensa in Ap. craccivora. We also characterized several parameters of H. defensa infection potentially relevant to the protective phenotype. We confirmed the presence of H. defensa in aphid hemolymph, where it potentially interacts with endoparasites, and performed real-time quantitative PCR (qPCR) to estimate symbiont and phage abundance during aphid development. We also examined strain variation of H. defensa and its bacteriophage at multiple loci, and despite our lines being collected in different regions of North America, they were infected with a nearly identical strains of H. defensa and APSE4 phage. The limited strain diversity observed for these defensive elements may result in relatively static protection profile for this defensive symbiosis.

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Section: Discussionmentioning

confidence: 75%

“…craccivora as factors constraining the spread of this symbiont in natural populations, given that this symbiont confers protection against parasitoids (37) yet remains at intermediate frequencies (0 to 85%) in natural populations (44,45). In addition, we sought to characterize certain attributes of H. defensa infecting Ap.…”

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confidence: 99%

Factors Limiting the Spread of the Protective Symbiont Hamiltonella defensa in Aphis craccivora Aphids

Dykstra

Weldon

Martinez

et al. 2014

Appl Environ Microbiol

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“…Also, the conditions that favor the maintenance of certain symbionts in the field may be absent in the lab, such as removal of natural enemies in the case of defensive symbionts [55]. Clearly, one of the main differences in the rearing conditions that the mealybugs encountered in this study is host plant, which is a common determinant of symbiont communities in herbivorous insects [4]. For example, in Acyrthosiphon pisum (Hemiptera: Aphididae) pea aphids, infection with specific bacterial endosymbionts is repeatedly associated with successful colonization of specific host plants [30].…”

Section: Discussionmentioning

confidence: 99%

Microbial Associates of the Vine Mealybug Planococcus ficus (Hemiptera: Pseudococcidae) under Different Rearing Conditions

et al. 2014

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Sap-feeding insects harbor diverse microbial endosymbionts that play important roles in host ecology and evolution, including contributing to host pest status. The vine mealybug, Planococcus ficus, is a serious pest of grapevines, vectoring a number of pathogenic grape viruses. Previous studies have shown that virus transmission is abolished when mealybugs are raised in the laboratory on potato. To examine the possible role of microbial symbionts in virus transmission, the archaeal, bacterial, and fungal microbiota of field and laboratory P. ficus were characterized using molecular and classical microbiological methods. Lab and field colonies of P. ficus harbored different microbiota. While both were dominated by the bacterial obligate nutritional symbionts Moranella and Tremblaya, field samples also harbored a third bacterium that was allied with cluster L, a lineage of bacterial symbionts previously identified in aphids. Archaea were not found in any of the samples. Fungal communities in field-collected mealybugs were dominated by Metschnikowia and Cladosporium species, while those from laboratory-reared mealybugs were dominated by Alternaria and Cladosporium species. In conclusion, this study has identified a diverse set of microbes, most of which appear to be facultatively associated with P. ficus, depending on environmental conditions. The role of various members of the mealybug microbiome, as well as how the host plant affects microbial community structure, remains to be determined.

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“…We screened the aphid clones for common aphid endosymbionts using (i) symbiont‐specific diagnostic PCR for all known A. craccivora symbionts and (ii) denaturing gradient gel electrophoresis (DGGE) following amplification of a variable region of 16S rRNA to detect any unexpected symbionts. Diagnostic PCR was conducted using previously published primers and protocols (Brady & White ; Brady et al . ) following a 10% w/v Chelex DNA extraction (Wulff et al .…”

Section: Methodsmentioning

confidence: 99%

“…Here, we investigate the role of facultative symbionts in the dietary breath in Aphis craccivora Koch (cowpea aphid). We previously reported a strong correlation between particular facultative symbionts and food plant use in A. craccivora (Brady & White ; Brady et al . ), a polyphagous aphid with a cosmopolitan distribution (Blackman & Eastop ).…”

Section: Introductionmentioning

confidence: 99%

Facultative endosymbionts mediate dietary breadth in a polyphagous herbivore

et al. 2015

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Summary Intraspecific variation in dietary breadth can influence important ecological and evolutionary processes, yet the mechanisms generating this variation are usually unknown. Maternally transmitted bacterial symbionts frequently infect insect herbivores, and many have been shown to mediate key ecological interactions. For polyphagous herbivores, infection with particular symbionts is often strongly correlated with feeding on particular plant species, suggesting that facultative symbionts might directly determine herbivore food plant specificity. However, previous tests of this hypothesis have returned inconsistent results, providing little empirical support for a causal relationship between facultative symbiont infection and dietary breadth. Here, we investigate whether heritable facultative symbionts mediate dietary breadth in the polyphagous aphid, Aphis craccivora. We first determined that asexual clones of the aphid differ dramatically in performance across two leguminous food plants, locust and alfalfa, and could be considered biotypes with distinct ecological characteristics. The heritable symbiont Arsenophonus is strongly associated with locust‐origin aphids. We created experimental lines that share aphid genotypes but differed with respect to Arsenophonus infection status, and compared performance across three food plant species. Naturally Arsenophonus‐infected clones performed 2–4× better on locust and up to 75% worse on two alternate plant species than uninfected controls, clearly demonstrating that Arsenophonus promotes specialization on locust. In both laboratory and field experiments, uninfected locust‐ and alfalfa‐origin clones exhibited similar and modest performance on locust, indicating that the ‘locust‐associated biotype’ would not exist without Arsenophonus. We also hypothesized that moving Arsenophonus, via transinfection, to an alfalfa‐origin lineage would improve performance on locust and serve to expand dietary breadth. Indeed, transinfection doubled aphid performance on locust and halved aphid performance on alfalfa. However, because this aphid lineage naturally performs better on alfalfa, the transinfected symbiont functionally equalized aphid performance between locust and alfalfa, making the alfalfa biotype more generalized. Thus, the same symbiont can either reduce or expand dietary breadth, depending on host genotype. Our results unequivocally demonstrate that symbiont gain or loss can instantaneously and substantially change the topology of food plant use in a polyphagous insect, modifying diet in ways that potentially influence the insect's ecological niche, evolutionary trajectory and pest status.

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Cowpea aphid (Aphis craccivora) associated with different host plants has different facultative endosymbionts

Cited by 96 publications

References 25 publications

Factors Limiting the Spread of the Protective Symbiont Hamiltonella defensa in Aphis craccivora Aphids

Factors Limiting the Spread of the Protective Symbiont Hamiltonella defensa in Aphis craccivora Aphids

Microbial Associates of the Vine Mealybug Planococcus ficus (Hemiptera: Pseudococcidae) under Different Rearing Conditions

Facultative endosymbionts mediate dietary breadth in a polyphagous herbivore

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