Abstract

Zoophytophagous insect predators can induce physiological responses in plants by activating defence signalling pathways, but whether plants can respond to facultative phytophagy by recruiting natural enemies remains to be investigated. In Y-tube olfactometer bioassays, using a system including a Vicia faba plant, the zoophytophagous predator Podisus maculiventris and the egg parasitoid Telenomus podisi, we first demonstrated that T. podisi females are attracted by broad bean plants damaged by feeding activity of P. maculiventris and on which host egg masses had been laid, while they are not attracted by undamaged plants or plants damaged by feeding activity alone. In a second experiment, we evaluated the impact of the invasive phytophagous pest Halyomorpha halys on this plant volatile-mediated tritrophic communication. Results showed that the invasive herbivorous adults do not induce plants to recruit the native egg parasitoid, but they can disrupt the local infochemical network. In fact, T. podisi females are not attracted by volatiles emitted by plants damaged by H. halys feeding alone or combined with oviposition activity, nor are they attracted by plants concurrently infested by P. maculiventris and H. halys, indicating the specificity in the parasitoid response and the ability of the invasive herbivore in interrupting the semiochemical communication between plants and native egg parasitoids. To the best of our knowledge, this is the first study showing that zoophytophagous predator attacks induce indirect plant defences similarly to those defence strategies adopted by plants as a consequence of single or concurrent infestations of herbivorous insects.

Highlights

  • Zoophytophagous insect predators can induce physiological responses in plants by activating defence signalling pathways, but whether plants can respond to facultative phytophagy by recruiting natural enemies remains to be investigated

  • There was no significant difference in preference to volatiles from bean plants damaged by P. maculiventris feeding or volatiles from unexposed plants (t = −0.006; df = 34; p = 0.99)

  • Unexposed plants were significantly more attractive to T. podisi than plants damaged by H. halys feeding and oviposition activities (t = −2.8; df = 34; p = 0.008) or by H. halys feeding (t = −2.47; df = 34; p = 0.018)

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Summary

Introduction

Zoophytophagous insect predators can induce physiological responses in plants by activating defence signalling pathways, but whether plants can respond to facultative phytophagy by recruiting natural enemies remains to be investigated. T. podisi females are not attracted by volatiles emitted by plants damaged by H. halys feeding alone or combined with oviposition activity, nor are they attracted by plants concurrently infested by P. maculiventris and H. halys, indicating the specificity in the parasitoid response and the ability of the invasive herbivore in interrupting the semiochemical communication between plants and native egg parasitoids. The mirid bug Nesidiocoris tenuis (Reuter) is a useful control agent of several tomato pest (e.g. whiteflies, thrips, leafminers, aphids, mites, lepidopterans) but occasionally, its feeding activity can damage the plants[21] It was www.nature.com/scientificreports demonstrated that the feeding and/or oviposition activities of zoophytophagous species can activate host plants defence mechanisms that affect performance of other insect herbivores and their natural enemies[22,23,24]. Species invasion can alter local trophic interactions toward various outcomes by adding new resources or by introducing novel interactions into local communities[39,40,41]

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