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Meta-analysis of parasitism levels of the invasive ladybird, Harmonia axyridis

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modified on 2017-11-08, 12:31
This repository provides the analysis of the parasitism data (table 3 and 4) from the following review paper :
Ceryngier, P., Nedvěd, O., Grez, A.A., Riddick, E.W., Roy, H.E., San Martin, G., Steenberg, T., Veselý, P., Zaviezo, T., Zúñiga-Reinoso, Á., Haelewaters, D., 2017. Predators and parasitoids of the harlequin ladybird, Harmonia axyridis, in its native range and invaded areas. Biological Invasions 1–23. doi:10.1007/s10530-017-1608-9

For Dinocampus coccinellae, we used both parasitism rates determined by dissection of field collected ladybirds and emergence level of the parasitoïds (in separate analyses) and for Phalacrotophora spp. we used only the parasitism level ascertained as the proportion of field collected ladybirds pupae giving rise to the parasitoïd larvae.

For these three dataset, we checked if we could find differences between regions (invaded or not), between species (H.axyridis vs other species) and if we could find temporal trends of parasitism levels in the invaded regions.

Summary of the paper :

Over the past 30 years, the harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) has rapidly spread in several continents and is considered an invasive alien species. The success of H. axyridis as an invader is often attributed to weak control by natural enemies. In this paper we provide an overview of current knowledge on predators and parasitoids of H. axyridis. The common feature of predators and parasitoids is that they directly kill exploited organisms. Currently available data show that H. axyridis, displaying a variety of chemical, mechanical, and microbiological anti-predator defenses, is usually avoided by predators. However, some birds and invertebrates can eat this ladybird without harmful consequences. The primary defenses of H. axyridis against parasitoids include immune response and physiological and nutritional unsuitability for parasitoid development. These defenses are probably relatively efficient against most ladybird parasitoids, but not against flies of the genus Phalacrotophora. The latter are idiobiont parasitoids and hence can evade the host's immune response. Indeed, rates of parasitism of H. axyridis by Phalacrotophora in the Palaearctic region (both in the native range in Asia and in Europe) are relatively high. While strong evidence for enemy release on the invasive populations of H. axyridis is lacking, several cases of parasitoid acquisition have been recorded in Europe, North America, and South America. We conclude that enemy release cannot be excluded as a possible mechanism contributing to the spread and increase of H. axyridis in the early stages of invasion, but adaptation of parasitoids may lead to novel associations which might offset previous effects of enemy release. However, further work is required to elucidate the population-level effects of such interactions.