DOI: 10.5061/dryad.ks10q
title: Data from: Associational resistance or susceptibility: the indirect interaction between chemically-defended and non-defended herbivore prey via a shared predator

description: Many organisms possess chemical defences against their natural enemies,
 which render them unpalatable or toxic when attacked or consumed. These
 chemically-defended organisms commonly occur in communities with non- or
 less-defended prey, leading to indirect interactions between prey species,
 mediated by natural enemies. Although the importance of enemy-mediated
 indirect interactions have been well documented (e.g. apparent
 competition), how the presence of prey chemical defences may affect
 predation of non-defended prey in terrestrial communities remains unclear.
 Here, an experimental approach was used to study the predator-mediated
 indirect interaction between a chemically-defended and non-defended pest
 aphid species. Using laboratory-based mesocosms, aphid community
 composition was manipulated to include chemically-defended (CD) aphids
 Brevicoryne brassicae, non-defended (ND) aphids Myzus persicae or a mixed
 assemblage of both species, on Brassica oleracea cabbage plants, in the
 presence or absence of a shared predator (Chrysoperla carnea larvae).
 Aphid population growth rates, aphid distributions on host plants and
 predator growth rates were measured. In single-species treatments, C.
 carnea reduced M. persicae population growth rate, but had no significant
 impact on B. brassicae population growth rate, suggesting B. brassicae
 chemical defences are effective against C. carnea. Chrysoperla carnea had
 no significant impact on either aphid species population growth rate in
 mixed-species treatments. Myzus persicae (ND) therefore experienced
 reduced predation in the presence of B. brassicae (CD) through a
 predator-mediated indirect effect. Moreover, predator growth rates were
 significantly higher in the M. persicae-only treatments than in either the
 B. brassicae-only or mixed-species treatments, suggesting predation was
 impaired in the presence of B. brassicae (CD). A trait-mediated indirect
 interaction is proposed, consistent with associational resistance, in
 which the predator, upon incidental consumption of chemically-defended
 aphids is deterred from feeding, releasing non-defended aphids from
 predatory control.
description: Associational Resistance
 or Susceptibility Complete Data FileThe data were collected
 at Lancaster Environment Centre in laboratory-based mesocosms. The data
 presented here in Microsoft Excel format were analysed using 'R'
 v.2.15.2 statistical software. For this, each worksheet was re-formatted
 to individual csv files and analysed seperately. The first worksheet
 presents the data regarding the population growth rate of Brevicoryne
 brassicae aphids. The second worksheet presents the data regarding the
 population growth rate of Myzus persicae aphids. The third worksheet
 presents the counts of B. brassicae and M. persicae at different sites
 within their host plants, when presented in single aphid species
 treatments. The fourth worksheet presents the counts of B. brassicae and
 M. persicae at different sites within their host plants, when presented in
 mixed aphid species treatments. The fifth and final worksheet presents the
 data of the predator, Chrysoperla carnea, growth rates.ARorAS.Data.CN.2016.xlsx