Data from: Impact of predicted precipitation scenarios on multitrophic interactions

1. Predicted changes in the frequency and intensity of extreme rainfall
events in the UK have the potential to disrupt terrestrial ecosystem
function. However, responses of different trophic levels to these changes
in rainfall patterns, and the underlying mechanisms, are not well
characterised. 2. This study aimed to investigate how changes in both the
quantity and frequency of rainfall events will affect the outcome of
interactions between plants, insect herbivores (above- and below- ground)
and natural enemies. 3. Hordeum vulgare L. plants were grown in controlled
conditions and in the field, and subjected to three precipitation
scenarios: ambient (based on a local 10 year average rainfall); continuous
drought (40% reduction compared to ambient); drought/ deluge (40%
reduction compared to ambient at a reduced frequency). The effects of
these watering regimes and wireworm (Agriotes species) root herbivory on
the performance of the plants, aphid herbivores above-ground (Sitobion
avenae, Metapolophium dirhodum and Rhopalosiphum padi), and natural
enemies of aphids including ladybirds (Harmonia axyridis) were assessed
from measurements of plant growth, insect abundance and mass, and assays
of feeding behaviour. 4. Continuous drought decreased plant biomass,
whereas reducing the frequency of watering events did not affect plant
biomass but did alter plant chemical composition. In controlled
conditions, continuous drought ameliorated the negative impact of
wireworms on plant biomass. 5. Compared to the ambient treatment, aphid
mass was increased by 15% when feeding on plants subjected to drought/
deluge; and ladybirds were 66% heavier when feeding on these aphids but
this did not affect ladybird prey choice. In field conditions, wireworms
feeding below-ground reduced the number of shoot-feeding aphids under
ambient and continuous drought conditions but not under drought/ deluge.
6. Predicted changes in both the frequency and intensity of precipitation
events under climate change have the potential to limit plant growth, but
reduce wireworm herbivory, while simultaneously promoting above-ground
aphid numbers and mass, with these effects transferring to the third
trophic level. Understanding the effect of future changes in precipitation
on species interactions is critical for determining their potential impact
on ecosystem functioning and constructing accurate predictions under
global change scenarios.