Multifunctional weaponry: The chemical defenses of earwigs

Gasch, Tina; Schott, M.; Wehrenfennig, Christoph; Düring, Rolf‐Alexander; Vilcinskas, Andreas

doi:10.1016/j.jinsphys.2013.09.006

Cited by 34 publications

(36 citation statements)

References 58 publications

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“…However, the amounts of these substances found in nest material are much lower than those that showed antifungal activity in vitro [69], [70]. Analogous results were obtained for antimicrobial benzoquinones emitted by earwigs [24]. Furthermore, chemical compounds isolated from glands of lower and higher termites have fungistatic activity not only by direct contact but also when conidia are incubated with their vapor [71], [72].…”

Section: Discussionmentioning

confidence: 91%

“…The remedial measures include complex immune systems [14], [15], behavioral adaptations [16], [17], [18], defensive symbiosis [9], [19], [20], [21], and the deployment of chemical compounds with antimicrobial effects [1], [2], [7], [22], [23], [24]. In the latter case, the composition and specific spatio-temporal pattern of deployment of antimicrobial secretions are likely to be crucial to the success of the antimicrobial strategy [1], [23], [25], [26].…”

Section: Introductionmentioning

confidence: 99%

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Multifaceted Defense against Antagonistic Microbes in Developing Offspring of the Parasitoid Wasp Ampulex compressa (Hymenoptera, Ampulicidae)

2014

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Effective antimicrobial strategies are essential adaptations of insects to protect themselves, their offspring, and their foods from microbial pathogens and decomposers. Larvae of the emerald cockroach wasp, Ampulex compressa, sanitize their cockroach hosts, Periplaneta americana, with a cocktail of nine antimicrobials comprising mainly (R)-(-)-mellein and micromolide. The blend of these antimicrobials has broad-spectrum antimicrobial activity. Here we explore the spatio-temporal pattern of deployment of antimicrobials during the development from egg to adult as well as their physico-chemical properties to assess how these aspects may contribute to the success of the antimicrobial strategy. Using gas chromatography/mass spectrometry (GC/MS) we show that larvae start sanitizing their food as soon as they have entered their host to feed on its tissue. Subsequently, they impregnate the cockroach carcass with antimicrobials to create a hygienic substrate for cocoon spinning inside the host. Finally, the antimicrobials are incorporated into the cocoon. The antimicrobial profiles on cockroach and wasp cocoon differed markedly. While micromolide persisted on the cockroaches until emergence of the wasps, solid-phase microextraction sampling and GC/MS analysis revealed that (R)-(-)-mellein vaporized from the cockroaches and accumulated in the enclosed nest. In microbial challenge assays (R)-(-)-mellein in the headspace of parasitized cockroaches inhibited growth of entomopathogenic and opportunistic microbes (Serratia marcescens, Aspergillus sydowii, Metarhizium brunneum). We conclude that, in addition to food sanitation, A. compressa larvae enclose themselves in two defensive walls by impregnating the cocoon and the cockroach cuticle with antimicrobials. On top of that, they use vaporous (R)-(-)-mellein to sanitize the nest by fumigation. This multifaceted antimicrobial defense strategy involving the spatially and temporally coordinated deployment of several antimicrobials in solution and vapor form has apparently evolved to reliably protect the larvae themselves and their food against a broad range of antagonistic microbes.

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Section: Discussionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Multifaceted Defense against Antagonistic Microbes in Developing Offspring of the Parasitoid Wasp Ampulex compressa (Hymenoptera, Ampulicidae)

2014

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“…External immune secretions present an important barrier to fungal infection (Hamilton et al ., ; Gasch et al ., ; Tragust et al ., ; Boos et al ., ), particularly in the interaction between T. castaneum and B. bassiana (Pedrini et al ., ). We show that antimicrobial secretions impose strong selection on parasites, where genotypes able to overcome the external immune barrier to infection are strongly favoured.…”

Section: Discussionmentioning

confidence: 99%

“…External immunity has evolved in numerous invertebrates as an additional defence against parasites (Yezerski et al, 2007;Hamilton et al, 2011;Gasch et al, 2013;Kay et al, 2014). An external immune system provides a defensive barrier at a relatively low cost by killing parasites before infection occurs and potentially protecting kin in close vicinity (Cotter and Kilner, 2010).…”

Section: Introductionmentioning

confidence: 99%

Highly potent host external immunity acts as a strong selective force enhancing rapid parasite virulence evolution

Rafaluk

Yang

Mitschke

et al. 2017

Environmental Microbiology

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Virulence is often under selection during host-parasite coevolution. In order to increase fitness, parasites are predicted to circumvent and overcome host immunity. A particular challenge for pathogens are external immune systems, chemical defence systems comprised of potent antimicrobial compounds released by prospective hosts into the environment. We carried out an evolution experiment, allowing for coevolution to occur, with the entomopathogenic fungus, Beauveria bassiana, and the red flour beetle, Tribolium castaneum, which has a well-documented external immune system with strong inhibitory effects against B. bassiana. After just seven transfers of experimental evolution we saw a significant increase in parasite induced host mortality, a proxy for virulence, in all B. bassiana lines. This apparent virulence increase was mainly the result of the B. bassiana lines evolving resistance to the beetles' external immune defences, not due to increased production of toxins or other harmful substances. Transcriptomic analyses of evolved B. bassiana implicated the up-regulation of oxidative stress resistance genes in the observed resistance to external immunity. It was concluded that external immunity acts as a powerful selective force for virulence evolution, with an increase in virulence being achieved apparently entirely by overcoming these defences, most likely due to elevated oxidative stress resistance.

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“…In F. auricularia , frass is unlikely to be used against predators, as adult defense mostly relies on the use of the forceps and on the spray of chemical repellents (Eisner ; Gasch et al. ). Similarly, frass alone has been shown to have no direct effect on conspecific attraction in F. auricularia (Hehar et al.…”

Section: Discussionmentioning

confidence: 99%

Influences of Relatedness, Food Deprivation, and Sex on Adult Behaviors in the Group‐living InsectForficula auricularia

et al. 2014

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The evolution of group living is generally associated with the emergence of social behaviors that ensure fitness benefits to group members. However, the expression of these behaviors may depend on group composition, which can vary over time with respect to sex, starvation status, and relatedness. Here, we investigated (1) whether adults of the group-living European earwig, Forficula auricularia, show cooperative behaviors toward conspecifics and (2) whether sex, food availability, and relatedness shape the nature and frequency of these behaviors. We conducted a full-factorial experiment using 108 unisexual pairs of adults, in which we manipulated these three factors and video-recorded the earwig behaviors for 45 min. Our results revealed that adults mostly expressed self-directed and aggressive behaviors. Nevertheless, they also showed allogrooming, a social behavior that offers scope for cooperation. Pairs of males displayed longer bouts of aggression and allogrooming (when it occurred) than pairs of females. Food deprivation had no effect on male behaviors, but females spent less time self-grooming and walking when they were food deprived. Finally, low relatedness between adults did not influence any of the measured behaviors, but exacerbated frass production, possibly due to social stress. Overall, these results indicate the limited role of cooperation among F. auricularia adults during their group-living phase.

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Multifunctional weaponry: The chemical defenses of earwigs

Cited by 34 publications

References 58 publications

Multifaceted Defense against Antagonistic Microbes in Developing Offspring of the Parasitoid Wasp Ampulex compressa (Hymenoptera, Ampulicidae)

Multifaceted Defense against Antagonistic Microbes in Developing Offspring of the Parasitoid Wasp Ampulex compressa (Hymenoptera, Ampulicidae)

Highly potent host external immunity acts as a strong selective force enhancing rapid parasite virulence evolution

Influences of Relatedness, Food Deprivation, and Sex on Adult Behaviors in the Group‐living InsectForficula auricularia

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