Abstract
Multitrophic interactions are likely to be altered by climate change but there is little empirical evidence relating the responses of herbivores and parasitoids to abiotic factors. Here we investigated the effects of drought on an above/below-ground system comprising a generalist and a specialist aphid species (foliar herbivores), their parasitoids, and a dipteran species (root herbivore).We tested the hypotheses that: (1) high levels of drought stress and below-ground herbivory interact to reduce the performance of parasitoids developing in aphids; (2) drought stress and root herbivory change the profile of volatile organic chemicals (VOCs) emitted by the host plant; (3) parasitoids avoid ovipositing in aphids feeding on plants under drought stress and root herbivory. We examined the effect of drought, with and without root herbivory, on the olfactory response of parasitoids (preference), plant volatile emissions, parasitism success (performance), and the effect of drought on root herbivory. Under drought, percentage parasitism of aphids was reduced by about 40-55% compared with well watered plants. There was a significant interaction between drought and root herbivory on the efficacy of the two parasitoid species, drought stress partially reversing the negative effect of root herbivory on percent parasitism. In the absence of drought, root herbivory significantly reduced the performance (e.g. fecundity) of both parasitoid species developing in foliar herbivores. Plant emissions of VOCs were reduced by drought and root herbivores, and in olfactometer experiments parasitoids preferred the odour from well-watered plants compared with other treatments. The present work demonstrates that drought stress can change the outcome of interactions between herbivores feeding above- and below-ground and their parasitoids, mediated by changes in the chemical signals from plants to parasitoids. This provides a new insight into how the structure of terrestrial communities may be affected by drought.
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Claims 6
Claim · model-written summary
Drought reduced aphid parasitism by about 40-55% relative to well watered plants.
- Taxon
- plantsViridiplantaee0
- Treatment
- droughte0
- Interactor
- aphidsAphidomorphae0pest
- Outcome
- percentage parasitism of aphidse0
- Direction
- reducede0
- Value
- about 40-55%e0
- Comparator
- well watered plantse0
Verbatim
e0“Under drought, percentage parasitism of aphids was reduced by about 40-55% compared with well watered plants”
Claim · model-written summary
Drought partly reversed the negative effect of root herbivory on parasitism.
Verbatim
e0“There was a significant interaction between drought and root herbivory on the efficacy of the two parasitoid species, drought stress partially reversing the negative effect of root herbivory on percent parasitism”
t0“Aphid Infested Plants”
Claim · model-written summary
Without drought, root herbivory reduced parasitoid fecundity.
- Taxon
- PlantsViridiplantaet0
- Treatment
- root herbivorye0
- Interactor
- parasitoid speciese0other
- Outcome
- fecundity) of both parasitoid speciese0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“In the absence of drought, root herbivory significantly reduced the performance (e.g. fecundity) of both parasitoid species developing in foliar herbivores”
t0“Aphid Infested Plants”
Claim · model-written summary
Drought reduced plant VOC emissions.
Not reportedComparator
Verbatim
e0“Plant emissions of VOCs were reduced by drought and root herbivores”
Claim · model-written summary
Root herbivores reduced plant VOC emissions.
- Taxon
- Plante0
- Treatment
- root herbivorese0
- Interactor
- root herbivorese0herbivore
- Outcome
- Plant emissions of VOCse0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“Plant emissions of VOCs were reduced by drought and root herbivores”
Claim · model-written summary
Parasitoids preferred odour from well-watered plants.
- Taxon
- plantsViridiplantaee0
- Interactor
- parasitoidse0other
- Outcome
- parasitoids preferred the odour from well-watered plantse0
- Comparator
- other treatmentse0
Verbatim
e0“in olfactometer experiments parasitoids preferred the odour from well-watered plants compared with other treatments”
The same questions in other papers
grazing · pest · Viridiplantae (plants)Results agree
1 paper in the same direction as this paper
- negative
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.