Plants under herbivore attack emit volatile organic compounds (VOCs) that can serve as foraging cues for natural enemies. Adult females of Lepidoptera, when foraging for host plants to deposit eggs, are commonly repelled by herbivore-induced VOCs, probably to avoid competition and natural enemies. Their larval stages, on the other hand, have been shown to be attracted to inducible VOCs. We speculate that this contradicting behavior of lepidopteran larvae is due to a need to quickly find a new suitable host plant if they have fallen to the ground. However, once they are on a plant they might avoid the sites with fresh damage to limit competition and risk of cannibalism by conspecifics, as well as exposure to natural enemies. To test this we studied the effect of herbivore-induced VOCs on the attraction of larvae of the moth Spodoptera littoralis and on their feeding behavior. The experiments further considered the importance of previous feeding experience on the responses of the larvae. It was confirmed that herbivore-induced VOCs emitted by maize plants are attractive to the larvae, but exposure to the volatiles decreased the growth rate of caterpillars at early developmental stages. Larvae that had fed on maize previously were more attracted by VOCs of induced maize than larvae that had fed on artificial diet. At relatively high concentrations synthetic green leaf volatiles, indicative of fresh damage, also negatively affected the growth rate of caterpillars, but not at low concentrations. In all cases, feeding by the later stages of the larvae was not affected by the VOCs. The results are discussed in the context of larval foraging behavior under natural conditions, where there may be a trade-off between using available host plant signals and avoiding competitors and natural enemies.
Keywords: Spodoptera littoralis, green leaf volatiles, maize, larval foraging behavior, host plant suitability
Citation: von Mérey GE, Veyrat N, D'Alessandro M and Turlings TCJ (2013) Herbivore-induced maize leaf volatiles affect attraction and feeding behavior of Spodoptera littoralis caterpillars. Front. Plant Sci. 4:209. doi: 10.3389/fpls.2013.00209
Received: 28 February 2013; Accepted: 02 June 2013;
Published online: 28 June 2013.
Edited by:Marcel Dicke, Wageningen University, Netherlands
Reviewed by:Anne M. Cortesero, University of Rennes1, France
Copyright © 2013 von Mérey, Veyrat, D'Alessandro and Turlings. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Ted C. J. Turlings, Laboratory for Fundamental and Applied Research in Chemical Ecology, Institute of Biology, University of Neuchâtel, Emile-Argand 11, C.P. 158, CH-2009 Neuchâtel, Switzerland e-mail: email@example.com