Microhabitat selection by ovipositing females and pre-diapause larvae of a Welsh population of Euphydryas aurinia (Lepidoptera: Nymphalidae)

Julia Pschera,John M Warren

doi:10.1007/s10841-018-0086-4

Abstract

Habitat requirements of the marsh fritillary Euphydryas aurinia have been studied intensively in recent years in order to inform conservation action on this rapidly declining species. Autecological studies have been undertaken on various spatial scales to account for differences in mobility between life stages. It has become clear that resource utilisation by the species varies between different geographic areas and also on a local scale. We studied the microhabitat surrounding Succisa pratensis plants chosen for oviposition and around resulting larval webs in a key Welsh population, UK. Microhabitat preferences were shown to differ between ovipositing females and pre-diapause larval groups. For oviposition, females showed a preference for host plants within clusters of S. pratensis surrounded by a relatively low sward. In contrast, larval webs were found in relatively high vegetation with relatively low S. pratensis cover in the immediate vicinity. The marked difference between oviposition and larval web microhabitat was achieved through very long distance dispersals undertaken by the pre-diapause larval groups. This gives rise to questioning the common assumption that pre-diapause larval web location can be used as a proxy for oviposition location. It also underpins the importance of managing E. aurinia habitats for maximum structural variability on a small scale.

Highlights

Many butterfly species are in decline across the globe
The control data suggest that plants with fewer than nine surrounding sub-squares containing parts of S. pratensis are fairly frequent (28.7%), no egg batches were found on such plants
Our results show that the microhabitats utilised for oviposition on the one hand and pre-diapause larval web establishment on the other hand differ significantly in terms of sward height and host plant cover

Summary

Introduction

Many butterfly species are in decline across the globe. In Britain, latest analyses of long-term monitoring data indicate that 70% of species have declined in occurrence and 57% in abundance since 1976 (Fox et al 2015). The marsh fritillary (Euphydryas aurinia) is a threatened butterfly species, listed in Annex II of the European Community Habitats and Species Directive (92/43/EEC). Environment and Rural Communities Act 2006 because the UK is one of the remaining strongholds of E. aurinia (van Swaay and Warren 1999). The main threats to E. aurinia are agricultural improvement and changes in agricultural practice, land abandonment and habitat fragmentation (Fowles and Smith 2006; Fox et al 2006). It has been widely recognised that conservation action needs to take into account all life stages of the species, and that habitat quality is determined by resource availability

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