Spatial and temporal diversity in hyperparasitoid communities of Cotesia glomerata on garlic mustard, Alliaria petiolata

Robin Heinen,Jeffrey A Harvey

doi:10.1111/een.12710

Robin Heinen, Jeffrey A Harvey

Open Access

https://doi.org/10.1111/een.12710

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Abstract

1. Interactions between two trophic levels can be very intimate, often making species dependent on each other, something that increases with specialisation. Some specialised multivoltine herbivores may depend on multiple plant species for their survival over the course of a growing season, especially if their food plants are short‐lived and grow at different times. Later generations may exploit different plant species from those exploited by previous generations.2. Multivoltine parasitoids as well as their natural enemies must also find their hosts on different food plants in different habitats across the season. Secondary hyperparasitoid communities have been studied on cocoons of the primary parasitoid, Cotesia glomerata (Hymenoptera: Braconidae), on black mustard (Brassica nigra) – a major food plant of its host, the large cabbage white (Pieris brassicae) – which grows in mid‐summer.3. Here, hyperparasitoid communities on C. glomerata pupal clusters were studied on an early‐season host, garlic mustard, Alliaria petiolata, over ‘time’ (one season, April–July) in six closely located ‘populations’ (c. 2 km apart), and within two different ‘areas’ at greater separation (c. 100 km apart). At the plant level, spatial effects of pupal ‘location’ (canopy or bottom) on the plant were tested.4. Although large‐scale separation (area) did not influence hyperparasitism, sampling time and small‐scale separation (population) affected hyperparasitism levels and composition of hyperparasitoid communities. Location on the plant strongly increased proportions of winged species in the canopy and proportions of wingless species in bottom‐located pupae.5. These results show that hyperparasitism varies considerably at the local level, but that differences in hyperparasitoid communities do not increase with spatial distance.

Highlights

Natural communities are made up of different species of organisms that often influence each other, often in large networks or food webs consisting of multiple trophic levels
These results show that hyperparasitism varies considerably at the local level, but that differences in hyperparasitoid communities do not increase with spatial distance
We tested the effect of large-scale spatial separation, smaller-scale separation as well as spatial separation on the same plant, and we tested how these processes varied over seasonal time

Summary

Introduction

Natural communities are made up of different species of organisms that often influence (or interact with) each other, often in large networks or food webs consisting of multiple trophic levels. Many insect herbivores harbour parasitoid ‘guilds’ consisting of species that are specialised in attacking different host stages, e.g. eggs, larvae or pupae (Godfray, 1994; Quicke, 2014). Primary hyperparasitoids attack the parasitoid larvae inside the body of the herbivore host, whereas secondary hyperparasitoids attack the pre-pupae or pupae of the primary parasitoid once it has emerged from the herbivore host Both examples represent a kind of ‘temporal partitioning’ of the host life cycle between different parasitoid species (Godfray, 1994), which is often necessary for multiple species to coexist on one host species (Haigh & Smith, 1972)

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