Olfactory response of a predatory mirid to herbivore induced plant volatiles: multiple herbivory vs. single herbivory

Abstract

Plants infested with a single herbivore species can attract natural enemies through the emission of herbivoreinduced plant volatiles (HIPVs). However, under natural conditions plants are often attacked by more than one herbivore species. We investigated the olfactory response of a generalist predators Macrolophus caliginosus to pepper infested with two-spotted spider mites, Tetranychus urticae, or green peach aphid, Myzus persicae, vs. plants infested with both herbivore species in a Y-tube olfactometer set up. In addition, the constituents of volatile blends from plants exposed to multiple or single herbivory were identified by gas chromatography-mass spectrometry (GC-MS). The mirid bugs showed a stronger response to volatiles emitted from plants simultaneously infested with spider mites and aphids than to those emitted from plants infested by just one herbivore, irrespective of the species. Combined with results from previous studies under similar conditions we infer that this was a reaction to herbivore induced plant volatiles. The GC-MS analysis showed that single herbivory induced the release of 22 additional compounds as compared with the volatiles emitted from clean plants. Quantitative analyses revealed that the amount of volatile blends emitted from pepper infested by both herbivores was significantly higher than that from pepper infested by a single herbivore. Moreover, two unique substances were tentatively identified (with a probability of 94% and 91%, respectively) in volatiles emitted by multiple herbivory damaged plants: a-zingiberene and dodecyl acetate.

Prospects for predatory mirid bugs as biocontrol agents of aphids in sweet peppers

“…It would be interesting to clarify whether these three species of predatory mirid bugs are able to associate prey odors as honeydew with the presence of prey. In this regard, Moayeri et al (2007) showed that M. pygmaeus do not seem to exploit odors emitted directly from the prey themselves, which suggests that mirids respond to herbivore-induced volatiles rather than to the prey itself. We found that the three species of mirids successfully preyed on M. persicae nymphs with significant differences among them, which depended on the predator gender or the instar preyed.…”

Plants under dual attack : consequences for plant chemistry and parasitoid behavior

“…De Rijk, Dicke & Poelman (2013) found that, out of 20 studies investigating carnivore preference when offered host-infested plants against plants infested with hosts and a non-host, only in 6 cases did the simultaneous presence of a non-host have a negative effect (for instance Rasmann & Turlings, 2007;Zhang et al, 2009;Zhang et al, 2013). In the majority of cases, when such dually challenged plants are offered against a plant with hosts only, enemies are frequently unaffected by, or even prefer dually infested plants both when the non-host is another herbivore (Moayeri et al, 2007;De Boer et al, 2008;Erb et al, 2010;Bukovinszky et al, 2012) or a plant pathogen (Cardoza et al, 2003b;Rostás et al, 2006). This, in combination with our results, suggests that overall the tritrophic cue appears quite robust, despite the potential for interference of the second attacker in the volatile composition.…”

“…Some studies have also examined effects on the third trophic level when both the JA and SA signal-transduction pathways are assumed to be induced, by combinations of herbivores and/or pathogens. While in one case attack by two herbivore species respectively affecting JA and SA signaling led to a decrease in carnivore attraction compared to single-species herbivory (Zhang et al, 2009), in all other cases carnivores were either equally attracted to, or preferred dually damaged plants over plants damaged by the host herbivore alone, for both dual attack by two herbivores (Moayeri et al, 2007;Erb et al, 2010) and a combination of herbivore and pathogen (Rostás et al, 2006). Interactions between the two primary signal-transduction pathways may play a role in the changes in VOC emissions in response to dual attacker events.…”

“…In other instances, total emission rates are affected. Dual herbivory involving different feeding guilds can lead to the majority of compounds being emitted in greater amounts than during single species herbivory (Moayeri et al, 2007;Hare & Sun, 2011) and HIPV emissions may also increase to levels higher than the expected additive effect of the two herbivores, indicating a synergistic effect on induction (De Boer et al, 2008). Total emissions can also be suppressed, as was demonstrated in cotton plants infested by piercing silverleaf whiteflies (B. tabaci) and chewing Spodoptera exigua caterpillars, where HIPV emissions in response to dual herbivory were reduced by 60% in comparison to caterpillar feeding alone (Rodriguez-Saona et al, 2003).…”

Invasion ecology of thrips in relation to seedling cotton

“…Studies that have analyzed the HIPV profiles of plants simultaneously fed upon by more than one species of herbivore have shown that HIPV blends differ both quantitatively and qualitatively when compared to the HIPV blends induced by single herbivore species (Delphia et al, 2007;Rodriguez-Saona et al, 2003;Moayeri et al, 2007). For example, quantitative differences were detected in the HIPV profiles of Nicotiana tabacum plants simultaneously feed upon by F. occidentalis and Heliothis virescens Fabricius (Lepidoptera:…”