Response of a Predatory ant to Volatiles Emitted by Aphid- and Caterpillar-Infested Cucumber and Potato Plants

Abstract

In response to herbivory by insects, various plants produce volatiles that attract enemies of the herbivores. Although ants are important components of natural and agro-ecosystems, the importance of herbivore-induced plant volatiles (HIPVs) as cues for ants for finding food sources have received little attention. We investigated responses of the ant Formica pratensis to volatiles emitted by uninfested and insect-infested cucumber (Cucumis sativus) and potato (Solanum tuberosum) plants. Cucumber plants were infested by the phloem-feeding aphid Aphis gossypii, the leaf chewer Mamestra brassicae or simultaneously by both insects. Potato plants were infested by either Aphis gossypii, by the leaf chewer Chrysodeixis chalcites or both. In olfactometer experiments, ants preferred volatile blends emitted by cucumber plants infested with M. brassicae caterpillars alone or combined with A. gossypii to volatiles of undamaged plants or plants damaged by A. gossypii only. No preference was recorded in choice tests between volatiles released by aphid-infested plants over undamaged plants. Volatiles emitted by potato plants infested by either C. chalcites or A. gossypii were preferred by ants over volatiles released by undamaged plants. Ants did not discriminate between potato plants infested with aphids and caterpillars over plants infested with aphids only. Plant headspace composition showed qualitative and/or quantitative differences between herbivore treatments. Multivariate analysis revealed clear separation between uninfested and infested plants and among herbivore treatments. The importance of HIPVs in indirect plant defence by ants is discussed in the context of the ecology of ant-plant interactions and possible roles of ants in pest management.

Endophytic colonization by Beauveria bassiana increases the resistance of tomatoes against Bemisia tabaci

“…Further testing was conducted using 1 g of fresh leaves soaked in anhydrous ethanol for 12 h. Leaf treatments included B. bassiana inoculation, leaves fed upon by the whitefly, and 0.05% Tween-80 sprayed as control. Air filtration and insect release were consistent with the previous tests, with the difference that 50 μl of 10% ethyl alcohol extracts from the treated and untreated leaves was added at the tube end (Schettino et al 2017). The experiment was designed as pairwise coupling, with statistics collected at 15 min intervals.…”

New Tools for Conservation Biological Control: Testing Ant-Attracting Artificial Nectaries to Employ Ants as Plant Defenders

“…Moreover, in some plants EFNs can be an induced defense in response to herbivory [27]. However, plant defense by ants against herbivores can also be mediated by other adaptations, such as certain volatiles [28][29][30][31][32]. Although the latter mechanism has only been documented in a few cases, it is easy to speculate that ants may act as plant defenders by attacking herbivores much more often than currently reported.…”

The discrepancy between fire ant recruitment to and performance on rodent carrion

“…Ant predation on carrion-visiting insects have been reported in several studies, as reviewed in Eubanks et al (2019). Such indirect attraction involving ants exists in the context of tritrophic interactions; Schettino et al 55 showed that Formica pratensis workers are attracted to the volatiles emitted from cucumber and potato plants when the plants were attacked by aphids and caterpillars, where the plants recruit ants for protection and in return, ants predate on the herbivores. In essence, the vertebrate carrion, vertebrate carrion-visitor and fire ant system may be another instance of a tritrophic interaction.…”