Publications - Faculty - Recently Submitted Faculty Publications 2008
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Stelinski - Journal of Chemical Ecology
Subterranean Herbivore-induced Volatiles Released by Citrus Roots upon Feeding by Diaprepes abbreviatus Recruit Entomopathogenic Nematodes
Ali J.G., Alborn H.T., and Stelinski L.L.
Abstract Herbivore induced volatile emissions benefit plant hosts by recruiting natural enemies of herbivorous insects. Such tritrophic interactions have been thoroughly examined in the above-ground terrestrial environment. Recently, similar signals have also been described in the subterranean environment, which may be an equally important indirect plant defense. The larvae of the root weevil (Diaprepes abbreviatus) are a serious pest of citrus. Infestations can be controlled by the use of entomopathogenic nematodes, yet the interactions between the plant, insect and nematode are poorly understood and remain unpredictable. In bioassays using a belowground six-arm olfactometer, citrus roots (‘Swingle citrumelo’ rootstock) recruited significantly more entomopathogenic nematodes (Steinernema diaprepesi) when infested with root weevil larvae than non-infested roots. Infested plants were more attractive to nematodes than larvae alone. Roots damaged by weevil larvae attracted more nematodes than mechanically damaged roots and sand controls. By dynamic in situ collection and GC-MS analysis of volatiles from soil, we determined that infested plants produced four terpene compounds that were not found in samples from non-infested roots or soil containing only larvae. Solvent extracts of weevil infested roots attracted more nematodes than extracts of non-infested roots in a two choice sand-column bioassay. These findings suggest that Swingle citrus roots release induced volatiles as an indirect defense in response to herbivore feeding and some of these induced volatiles most likely function as attractants for entomopathogenic nematodes.
