A "clean" alien species? Parasites of the invasive ladybird Harmonia axyridis (Coleoptera: Coccinellidae)

Krzysztof Dudek,Piotr Tryjanowski,Pawel Sienkiewicz,Dariusz J Gwiazdowicz

doi:10.14411/eje.2017.044

Krzysztof Dudek, Piotr Tryjanowski + Show 2 more

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https://doi.org/10.14411/eje.2017.044

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Abstract

The multicoloured Asian ladybird Harmonia axyridis is an invasive insect that can negatively influence biodiversity and human economy in invaded areas. According to the enemy release hypothesis, invasive alien species are often little affected by parasites and other enemies. We studied the prevalence of common parasites of insects infesting and infecting H. axyridis in NW Poland. A large sample of 2351 individuals was collected and divided into two groups: 1180 beetles were dissected and examined for the presence of eugregarines, nematodes and Laboulbeniales fungi, and 751 were checked for phoretic mites. Our results show that H. axyridis is indeed parasitized infrequently. The prevalence of eugregarines and nematodes was very low (1.5% and 0.4%, respectively). No specimens of Laboulbeniales or phoretic mites were found. Our study indicates that in NW Poland H. axyridis is rarely infested or infected by parasites. This paper reports for the first time the infection of H. axyridis by the eugregarine Gregarina barbarara.

Highlights

One of the reasons for rapid and successful invasions by non native species might be their escape from natural enemies – “enemy release hypothesis” (Torchin et al, 2003; Colautti et al, 2004; Heger & Jeschke, 2014)
The main goal of this study was to search for common parasites of ladybirds infesting H. axyridis in an invaded area (NW Poland): eugregarines, fungi and mites
The largest group of 1180 individuals was used for searching for eugregarines, nematodes and Laboulbeniales fungi, and the remaining 751 beetles were checked for mites

Summary

Introduction

One of the reasons for rapid and successful invasions by non native species might be their escape from natural enemies – “enemy release hypothesis” (Torchin et al, 2003; Colautti et al, 2004; Heger & Jeschke, 2014). The main goal of this study was to search for common parasites of ladybirds infesting H. axyridis in an invaded area (NW Poland): eugregarines, fungi and mites. These organisms are often found to infect/infest insects, so they may decrease insect survival and play an important role in the worldwide spread of H. axyridis. In this study we did not investigate parasitoids, such as Dinocampus coccinellae and Phalacrotophora spp., which may contribute to the suppression of the invader (Ware et al, 2010)

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