Bacterial phylogeny predicts volatile organic compound composition and olfactory response of an aphid parasitoid

Goelen, Tim; Sobhy, Islam S.; Vanderaa, Christophe; Wäckers, Félix; Rediers, Hans; Wenseleers, Tom; Jacquemyn, Hans; Lievens, Bart

doi:10.1111/oik.07301

Cited by 20 publications

(21 citation statements)

References 69 publications

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“…Entrained volatiles were eluted in 750 μL diethyl ether and were stored in 1.1 mL glass microvials at −20 °C until further use. In line with previous work, 27,28 GC‐FID (flame ionization detector) analysis yielded highly similar mVOC profiles across the biological replicates for each treatment. Therefore, all remaining experiments (coupled gas chromatography‐electroantennography, GC–EAG, and behavioural assays, see later) were performed with only one of the three replicates.…”

Section: Methodssupporting

confidence: 87%

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Identification and application of bacterial volatiles to attract a generalist aphid parasitoid: from laboratory to greenhouse assays

Goelen¹,

Vuts

Sobhy

et al. 2020

Pest Management Science

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BACKGROUND Recent studies have shown that microorganisms emit volatile compounds that affect insect behaviour. However, it remains largely unclear whether microbes can be exploited as a source of attractants to improve biological control of insect pests. In this study, we used a combination of coupled gas chromatography‐electroantennography (GC–EAG) and Y‐tube olfactometer bioassays to identify attractive compounds in the volatile extracts of three bacterial strains that are associated with the habitat of the generalist aphid parasitoid Aphidius colemani, and to create mixtures of synthetic compounds to find attractive blends for A. colemani. Subsequently, the most attractive blend was evaluated in two‐choice cage experiments under greenhouse conditions. RESULTS GC–EAG analysis revealed 20 compounds that were linked to behaviourally attractive bacterial strains. A mixture of two EAG‐active compounds, styrene and benzaldehyde applied at a respective dose of 1 μg and 10 ng, was more attractive than the single compounds or the culture medium of the bacteria in Y‐tube olfactometer bioassays. Application of this synthetic mixture under greenhouse conditions resulted in significant attraction of the parasitoids, and outperformed application of the bacterial culture medium. CONCLUSION Compounds isolated from bacterial blends were capable of attracting parasitoids both in laboratory and greenhouse assays, indicating that microbial cultures are an effective source of insect attractants. This opens new opportunities to attract and retain natural enemies of pest species and to enhance biological pest control.

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Section: Methodssupporting

confidence: 87%

“…Three bacterial isolates that produce volatile blends that are attractive to A. colemani 27,28 were used in this study (Supporting Information, Table S1). Strains were isolated from different sources from the habitat of Aphidius parasitoids.…”

Section: Methodsmentioning

confidence: 99%

Identification and application of bacterial volatiles to attract a generalist aphid parasitoid: from laboratory to greenhouse assays

Goelen¹,

Vuts

Sobhy

et al. 2020

Pest Management Science

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“…viridescens microbiomes were examined for anti- Bd function by matching reads to sequences from approximately 7000 cultures tested against Bd [ 40 ]. Importantly, we acknowledge that the function of microbial secondary metabolites can differ among Bd isolates [ 85 ], and 16S rRNA sequences do not faithfully indicate secondary metabolite production, though function may be a phylogenetically conserved trait [ 86 ]. Thus, ascribing function of microbial communities comes with uncertainty, but may be useful for between-group comparisons [ 87 ].…”

Section: Methodsmentioning

confidence: 99%

Winter is coming–Temperature affects immune defenses and susceptibility to Batrachochytrium salamandrivorans

et al. 2021

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Environmental temperature is a key factor driving various biological processes, including immune defenses and host-pathogen interactions. Here, we evaluated the effects of environmental temperature on the pathogenicity of the emerging fungal pathogen, Batrachochytrium salamandrivorans (Bsal), using controlled laboratory experiments, and measured components of host immune defense to identify regulating mechanisms. We found that adult and juvenile Notophthalmus viridescens died faster due to Bsal chytridiomycosis at 14°C than at 6 and 22°C. Pathogen replication rates, total available proteins on the skin, and microbiome composition likely drove these relationships. Temperature-dependent skin microbiome composition in our laboratory experiments matched seasonal trends in wild N. viridescens, adding validity to these results. We also found that hydrophobic peptide production after two months post-exposure to Bsal was reduced in infected animals compared to controls, perhaps due to peptide release earlier in infection or impaired granular gland function in diseased animals. Using our temperature-dependent susceptibility results, we performed a geographic analysis that revealed N. viridescens populations in the northeastern United States and southeastern Canada are at greatest risk for Bsal invasion, which shifted risk north compared to previous assessments. Our results indicate that environmental temperature will play a key role in the epidemiology of Bsal and provide evidence that temperature manipulations may be a viable disease management strategy.

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“…To determine predicted anti‐ Bd function, sequences were compared to the Antifungal Isolates Database (Woodhams et al., 2015) using the vsearch cluster‐features‐closed‐reference script (Rognes et al., 2016) to identify sequences with 99% match to bacterial isolates previously shown to inhibit Bd growth in culture by at least 80% compared to controls. This estimation of microbial community function comes with uncertainty, but may be useful for between‐group comparisons (Langille et al., 2013), and we note that the function of microbial secondary metabolites can differ among Bd isolates (Antwis & Harrison, 2018), and that 16S rRNA sequences may not faithfully indicate secondary metabolite production, although function can be a phylogenetically conserved trait (Goelen et al., 2020).…”

Section: Methodsmentioning

confidence: 99%

Preparatory immunity: Seasonality of mucosal skin defences and Batrachochytrium infections in Southern leopard frogs

Sage

LaBumbard

Reinert

et al. 2020

Journal of Animal Ecology

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Accurately predicting the impacts of climate change on wildlife health requires a deeper understanding of seasonal rhythms in host–pathogen interactions. The amphibian pathogen, Batrachochytrium dendrobatidis (Bd), exhibits seasonality in incidence; however, the role that biological rhythms in host defences play in defining this pattern remains largely unknown. The aim of this study was to examine whether host immune and microbiome defences against Bd correspond with infection risk and seasonal fluctuations in temperature and humidity. Over the course of a year, five populations of Southern leopard frogs (Rana [Lithobates] sphenocephala) in Tennessee, United States, were surveyed for host immunity, microbiome and pathogen dynamics. Frogs were swabbed for pathogen load and skin bacterial diversity and stimulated to release stored antimicrobial peptides (AMPs). Secretions were analysed to estimate total hydrophobic peptide concentrations, presence of known AMPs and effectiveness of Bd growth inhibition in vitro. The diversity and proportion of bacterial reads with a 99% match to sequences of isolates known to inhibit Bd growth in vitro were used as an estimate of predicted anti‐Bd function of the skin microbiome. Batrachochytrium dendrobatidis dynamics followed the expected seasonal fluctuations—peaks in cooler months—which coincided with when host mucosal defences were most potent against Bd. Specifically, the concentration and expression of stored AMPs cycled synchronously with Bd dynamics. Although microbiome changes followed more linear trends over time, the proportion of bacteria that can function to inhibit Bd growth was greatest when risk of Bd infection was highest. We interpret the increase in peptide storage in the fall and the shift to a more anti‐Bd microbiome over winter as a preparatory response for subsequent infection risk during the colder periods when AMP synthesis and bacterial growth is slow and pathogen pressure from this cool‐adapted fungus is high. Given that a decrease in stored AMP concentrations as temperatures warm in spring likely means greater secretion rates, the subsequent decrease in prevalence suggests seasonality of Bd in this host may be in part regulated by annual immune rhythms, and dominated by the effects of temperature.

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Bacterial phylogeny predicts volatile organic compound composition and olfactory response of an aphid parasitoid

Cited by 20 publications

References 69 publications

Identification and application of bacterial volatiles to attract a generalist aphid parasitoid: from laboratory to greenhouse assays

Identification and application of bacterial volatiles to attract a generalist aphid parasitoid: from laboratory to greenhouse assays

Winter is coming–Temperature affects immune defenses and susceptibility to Batrachochytrium salamandrivorans

Preparatory immunity: Seasonality of mucosal skin defences and Batrachochytrium infections in Southern leopard frogs

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