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

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

https://link.springer.com/article/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.