DOI: 10.5061/dryad.m195j
title: Data from: Parasitoid wasps indirectly suppress seed production by stimulating consumption rates of their seed-feeding hosts

description: 1. In parasitoid–herbivore–plant food chains, parasitoids may be
 simultaneously linked with both herbivore hosts and plants, as occurs when
 herbivores attacked by parasitoids continue to consume plants although
 they are destined to die. This peculiar property may cause parasitoids to
 confer a differential trophic cascading effect on plants than that known
 for typical predators. 2. We hypothesized that larval koinobiont
 parasitoids would confer an immediate negative effect on plant seed
 production by stimulating consumption of their seed-predator hosts. We
 tested this hypothesis in an alpine parasitic food chain of plant seeds,
 pre-dispersal seed predators (tephritid fly larvae) and koinobiont
 parasitoids using field observations, a field experiment and a microcosm
 study. 3. We first compared observed seed production in (i) non-infected
 capitula, (ii) capitula infected only by seed predators (tephritid flies)
 and (iii) capitula infected by both seed predators and their parasitoids
 in five Asteraceae species. Consistent with our hypothesis, seed loss in
 the capitula with both seed predators and parasitoids was significantly
 greater than in the capitula infested only by seed predators. 4. This
 effect was replicated in a controlled field experiment focusing on the
 most common parasitoid–seed predator–plant interaction chain in our
 system, in which confounding factors (e.g. density and phenology) were
 excluded. Here, we show that parasitoids indirectly decreased plant seed
 production by changing the behaviour of seed predators. 5. In a microcosm
 study, we show that larval parasitoids significantly extended the growth
 period and increased the terminal size of their host tephritid maggots.
 Thus, parasitoids suppressed plant seed production by stimulating the
 growth and consumption of the fly maggots. 6. In contrast to the typical
 predator-induced trophic cascade, we highlight the significance of
 parasitoids indirectly decreasing plant fitness by stimulating consumption
 by seed predators. Future studies on trophic interactions should consider
 the net effect of both increased consumption by seed predators and their
 death after development of parasitoids.
description: Figure 1. The effect of
 Tephritid flies and Wasps on seed damage in five Asteraceae host
 speciesThe Minimum,first
 quantile,median,third quantile, Maximum, and mean are provided for each
 treatment in the observational study.Data_Figure1.xlsxFigure 2. Number of damaged seeds and total seed number per capitulum in treatments with No insect (N), Wasp-only (W), Tephritid (T), and Tephritid and Wasp (TW) in Saussurea nigrescensThe Minimum,first quantile,median,third quantile, Maximum, and mean are provided for each treatment in the controlled field experiment.Data-Figure2.xlsxFigure 3. Pupation time (days after the beginning of the experiment), pupal length, and pupal (fresh) mass of healthy and parasitized tephritid maggots.The Minimum,first quantile,median,third quantile, Maximum, and mean are provided for each treatment in the microcosm experiment.Data_Figure3.xlsx