Intraguild Interactions between Egg Parasitoids: Window of Opportunity and Fitness Costs for a Facultative Hyperparasitoid

Antonino Cusumano,Stefano Colazza,Ezio Peri,Jeremy N Mcneil,Valentina Amodeo,Nicholas J Mills

doi:10.1371/journal.pone.0064768

Antonino Cusumano, Stefano Colazza + Show 4 more

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https://doi.org/10.1371/journal.pone.0064768

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Journal: PLoS ONE	Publication Date: May 21, 2013
Citations: 21	License type: CC BY 4.0

Affiliation: University of Palermo, Western University

Abstract

We investigated intraguild interactions between two egg parasitoids of Nezara viridula (L.) (Heteroptera: Pentatomidae), Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) and Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae), as the former has the potential to be a facultative hyperparasitoid of the latter. We assessed the suitability of N. viridula eggs for the development of O. telenomicida as a function of egg age when they were unparasitized, or had been attacked by T. basalis at different times prior to exposure to O. telenomicida females. Ooencyrtus telenomicida can exploit healthy N. viridula host eggs up to 5 days of age, just prior to the emergence of N. viridula. This window of opportunity can be extended for an additional 6–7 days through interspecific competition or facultative hyperparasitism. While there are minor fitness costs for O. telenomicida as the result of interspecific larval competition, those costs are greater with facultative hyperparasitism. In choice assays O. telenomicida females discriminated between different quality N. viridula eggs, avoiding those where their progeny would have to develop as facultative hyperparasitoids of T. basalis. Results are discussed with respect to the possible effects that the costs of intraguild parasitism might have on biological control programmes.

Highlights

Intraguild interactions occur among organisms sharing a common resource [1] and ‘‘intraguild predation’’ (IGP), which is common in natural populations [2], occurs when two species that share a common host, under certain circumstances, prey upon each other [3]
There was a significant effect of host age on the number of adult O. telenomicida emerging from unparasitized N. viridula eggs (Fig. 1A; F = 3.21, df = 4, 45, P,0.05;), being significantly lower from 5 than from 1 day old hosts
Similar temporal effects were observed when O. telenomicida oviposited in N. viridula eggs that had been attacked by T. basalis when the eggs were 1 day old (Fig. 1B; F = 20.26, df = 7, 72, P,0.001) or 3 days old

Summary

Introduction

Intraguild interactions occur among organisms sharing a common resource [1] and ‘‘intraguild predation’’ (IGP), which is common in natural populations [2], occurs when two species that share a common host, under certain circumstances, prey upon each other [3]. Rosenheim et al [8] noted that intraguild parasitism can occur when one guild member is a facultative hyperparasitoid. Such species can act either as a primary parasitoid utilising some life stage of an herbivorous insect as a host, or as a hyperparasitoid where it uses a primary parasitoid as a host. A facultative hyperparasitoid can exploit a healthy host but if it oviposits in a common host that has been already attacked by another species there are two possible outcomes: interspecific larval competition will occur if the competitor’s offspring has not yet consumed all of the host resources, but if it has hyperparasitism will occur [8,9]

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