Volatile-mediated foraging behaviour of three parasitoid species under conditions of dual insect herbivore attack. (January 2016)

• Record Type: Journal Article
• Authors: Ponzio, Camille; Cascone, Pasquale; Cusumano, Antonino; Weldegergis, Berhane T.; Fatouros, Nina E.; Guerrieri, Emilio; Dicke, Marcel; Gols, Rieta
• Is Part Of: Animal behaviour. Volume 111(2016)
• Page Start: 197
• Page End: 206
• Publication Date: 2016-01
• Subjects: herbivore-induced plant volatiles -- indirect defence -- multiple attack -- multitrophic interactions -- oviposition-induced plant volatiles; Animal behavior -- Periodicals; 591.5
• DOI: 10.1016/j.anbehav.2015.10.024
• Languages: English
• ISSNs: 0003-3472

Abstract

Abstract : Infochemicals play an important role in structuring intra- and interspecific interactions. Many parasitoid wasp species rely on herbivory or oviposition-induced plant volatiles (HIPVs/OIPVs) to locate their herbivorous hosts, and must cope with variation in the volatile blends due to factors such as plant/host species, herbivore density or attack by several herbivores. However, little is known about how dual herbivory or changes in herbivore density affect multiple parasitoid species, each attacking a different herbivore, in the same system. In a natural system, we investigated the effect of dual attack on the ability of three parasitoid species to differentiate between volatiles induced by hosts and those induced by a combination of hosts and nonhosts. Black mustard, Brassica nigra, plants were infested with eggs or caterpillars of Pieris brassicae, alone or in combination with different densities of Brevicoryne brassicae aphids. We determined the ability of three different parasitoid species that parasitize either P. brassicae eggs ( Trichogramma brassicae ), caterpillars ( Cotesia glomerata ) or B. brassicae aphids ( Diaeretiella rapae ) to discriminate between the induced volatiles, and analysed the plant volatile blends. Dual infestation did not affect the parasitoid species equally and aphid infestation altered, in a density-dependent manner, the volatile-mediated foraging of all three parasitoid species. Chemical analyses of the volatile blends revealed nonlinear emission patterns in relation to aphid density in both plants attacked by aphids alone and in plants attacked by a combination of aphids and caterpillars. Simple correlations between behaviour and volatile emissions in pairwise comparisons suggest the importance of certain volatiles explaining attraction, whereas dose-response type analyses reveal that these simple correlation analyses provide an incomplete picture. Highlights: We studied the effects of dual herbivory on three different parasitoid species. Egg and caterpillar parasitoid foraging were affected by aphid nonhosts. Foraging by aphid parasitoids was not affected by the presence of nonhost caterpillars. For all three wasp species there was a negative, aphid density-dependent effect. Plant volatile emissions respond nonlinearly to increasing aphid density.