Ant-like Traits in Wingless Parasitoids Repel Attack from Wolf Spiders

Abstract

A recent study showed that a wingless parasitoid, Gelis agilis, exhibits a suite of ant-like traits that repels attack from wolf spiders. When agitated, G. agilis secreted 6-methyl-5-hepten-2-one (sulcatone), which a small number of ant species produce as an alarm/panic pheromone. Here, we tested four Gelis parasitoid species, occurring in the same food chain and microhabitats, for the presence of sulcatone and conducted two-species choice bioassays with wolf spiders to determine their degree of susceptibility to attack. All four Gelis species, including both winged and wingless species, produced sulcatone, whereas a closely related species, Acrolyta nens, and the more distantly related Cotesia glomerata, did not. In two-choice bioassays, spiders overwhelmingly rejected the wingless Gelis species, preferring A. nens and C. glomerata. However, spiders exhibited no preference for either A. nens or G. areator, both of which are winged. Wingless gelines exhibited several ant-like traits, perhaps accounting for the reluctance of spiders to attack them. On the other hand, despite producing sulcatone, the winged G. areator more closely resembles other winged cryptines like A. nens, making it harder for spiders to distinguish between these two species. C. glomerata was also preferred by spiders over A. nens, suggesting that other non-sulcatone producing cryptines nevertheless possess traits that make them less attractive as prey. Phylogenetic reconstruction of the Cryptinae reveals that G. hortensis and G. proximus are ‘sister’species, with G. agilis, and G.areator in particular evolving along more distant trajectories. We discuss the possibility that wingless Gelis species have evolved a suite of ant-like traits as a form, of mimicry to repel predators on the ground.

Is mimicry a diversification-driver in ants? Biogeography, ecology, ethology, genetics and morphology define a second West-PalaearcticColobopsisspecies (Hymenoptera: Formicidae)

“…lateralis and Cr. scutellaris, while Harvey et al (2018) described the anti-predatory function of ant-mimicry in Gelis spp., Komatsu (1961) Interspecific but intrageneric trail-following described for some ants is likely relatable to phylogenetic proximity and morphofunctional and behavioural similarities or similar foraging strategies among species (e.g. Grasso et al, 2002 and references therein).…”

“…On the other hand, myrmecomorph species resemble their ant model thanks to morphological and/or behavioural adaptations (e.g. Komatsu 1961;Jackson & Drummond, 1974;Oliveira & Sazima, 1984;Oliveira 1988;Cobben, 1986;McIver, 1987;McIver & Stonedahl, 1993;Trjapitzin & Trjapitzin, 1995;Cassis & Wall, 2010;Chandler, 2010;Durkee et al, 2011;Huang et al, 2011;Cushing, 2012;Pekár, 2014;Corcobado et al, 2016;Pekár et al, 2017;Harvey et al, 2018;de L. Nascimento & Perger, 2018;Gnezdilov, 2019). The main aim of myrmecomorphism is predation avoidance: compared to the mimics, models usually possess superior defensive mechanisms and are also more numerous.…”

“…As such, they are usually interpreted as Batesian mimics (e.g. Jackson & Drummond, 1974;McIver, 1987;Durkee et al, 2011;Huang et al, 2011;Cushing, 2012;Harvey et al, 2018), whose evolution can be favoured by model abundance (Kikuchi & Pfenning, 2010).…”

Reproduction and Offspring Sex Ratios Differ Markedly among Closely Related Hyperparasitoids Living in the Same Microhabitats

“…Species identification was made by Dr. Martin Schwarz, one of the world's leading experts on the Cryptinae, who is based at the Biologiezentrum in Linz, Austria. A recent phylogenetic reconstruction of the three geline species is shown in Harvey et al (2018).…”

“…(4) Ectoparasitic idiobisis, whereby eggs are laid by female parasitoids on the body surface of paralyzed hosts (Mayhew and Blackburn, 1999). (5) Wingless adults, which contrasts with most parasitoid taxa that are fully winged (Schwarz and Shaw 1999;Harvey et al 2018). Despite these overlapping traits, the three species successfully co-occur in grassy meadow and forest edges across much of Eurasia, including the Netherlands.…”