Exposure of Lima Bean Leaves to Volatiles from Herbivore-Induced Conspecific Plants Results in Emission of Carnivore Attractants: Active or Passive Process?

Abstract

There is increasing evidence that volatiles emitted by herbivore-damaged plants can cause responses in downwind undamaged neighboring plants, such as the attraction of carnivorous enemies of herbivores. One of the open questions is whether this involves an active (production of volatiles) or passive (adsorption of volatiles) response of the uninfested downwind plant. This issue is addressed in the present study. Uninfested lima bean leaves that were exposed to volatiles from conspecific leaves infested with the spider mite Tetranychus urticae, emitted very similar blends of volatiles to those emitted from infested leaves themselves. Treating leaves with a protein-synthesis inhibitor prior to infesting them with spider mites completely suppressed the production of herbivore-induced volatiles in the infested leaves. Conversely, inhibitor treatment to uninfested leaves prior to exposure to volatiles from infested leaves did not affect the emission of volatiles from the exposed, uninfested leaves. This evidence supports the hypothesis that response of the exposed downwind plant is passive. T. urticae-infested leaves that had been previously exposed to volatiles from infested leaves emitted more herbivore-induced volatiles than T. urticae-infested leaves previously exposed to volatiles from uninfested leaves. The former leaves were also more attractive to the predatory mite, Phytoseiulus persimilis, than the latter. This shows that previous exposure of plants to volatiles from herbivore-infested neighbors results in a stronger response of plants in terms of predator attraction when herbivores damage the plant. This supports the hypothesis that the downwind uninfested plant is actively involved. Both adsorption and production of volatiles can mediate the attraction of carnivorous mites to plants that have been exposed to volatiles from infested neighbors.

Prohydrojasmon treatment of lima bean plants reduces the performance of two-spotted spider mites and induces volatiles

“…Furthermore, changes affecting the performance of TSSMs required at least 3 days (Figure 2). Choh et al (2004) reported that JA applied to the soil of potted lima bean plants reduced the numbers of eggs laid on those plants. The data in this study clarified that PDJ treatment of lima bean leaves affected TSSMs similarly to JA treatment.…”

“…Choh et al (2004) showed that not only JA but also benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), a functional analog of SA, applied to the soil of potted lima bean plants reduced the numbers of eggs laid on those plants. Shimoda et al (2002) reported that females of the predatory Oligota kashmirica benefica (Coleoptera: Staphylinidae) exhibited a significant preference for JA 'methyl salicylate (MeSA)-treated lima bean leaves over uninfested leaves, and females predatory Scolothrips takahashii (Thysanoptera: Thripidae) significantly preferred both MeSA ( and JA'MeSA-treated lima bean leaves to uninfested leaves.…”

Induced defence in lima bean plants exposed to the volatiles from two-spotted spider mite-infested conspecifics is independent of the major protein expression

“…Farag et al (2005) reported that (Z)-3-hexenol-exposed maize plants accumulated the transcripts of the gene for proteinase inhibitor, but its protein was not accumulated. Moreover, the defence response primed by volatiles has been reported in lima beans, poplar plants and maize (Choh et al 2004;Engelberth et al 2004;Ton et al 2007;Frost et al 2008). For example, Choh et al (2004) demonstrated that volatiles from mite-infested lima bean plants primed intact conspecific plants for the production of herbivore-induced natural enemy attractants upon subsequent herbivory.…”

Duration of Priming of Two Indirect Plant Defenses

“…3 We also reported that exposure to HIPVs, produced in response to T. urticae damage, 4 primed the induced production of extrafloral nectar (EFN; an alternative food source for predators 10,11 in lima bean plants. An intriguing question is whether the two primed defenses work as a battery against T. urticae.…”

“…1,2 Recently, it was reported that the emission of HIPVs primed defenses against herbivores in neighboring intact plants. [3][4][5][6][7] Thus, HIPVs also mediate interactions between infested and intact plants. 8 The enhanced defense in response to HIPVs in intact plants is called 'priming', which has been studied intensively in plant-pathogen interactions, 9 but not so in plant-insect interactions.…”