The Recruitment of Parasitoid Species to Two Invading Herbivores

Temporal and spatial variations in the parasitoid complex of the horse chestnut leafminer during its invasion of Europe

“…The immediate adoption of C. ohridella by M. frontalis is therefore an impressive example for behavioral flexibility. Probably, this idiobiont species searches for hosts on virtually any available tree in the environment, which may be very effective for generalist parasitoids (Godfray et al 1995). However, our results also suggest that parasitism by M. frontalis did not increase with the leafminers' residence time indicating a lack of further adaptation.…”

“…Although parasitoid richness was roughly similar, parasitism rates were significantly lower in C. ohridella than in the two Phyllonorycter species. Phyllonorycter leucographella and P. platani reached parasitism rates of 56.6 and 37.5%, respectively, \10 years after their introduction into the UK (Godfray et al 1995). The low parasitism rates of C. ohridella have previously been used to demonstrate the lack of adaptation of native parasitoids to this introduced host (Girardoz et al 2007c;Grabenweger 2004;Grabenweger et al 2005a).…”

“…There was a weak indication that this process would at least require a period of 150 years, but may also last 10,000 years. Meanwhile, Godfray et al (1995) analyzed the parasitoid recruitment of two leafminers roughly 10 years after they had invaded the British Islands from mainland Europe. Contrary to Cornell and Hawkins (1993), the parasitoid complexes of these invasive Phyllonorycter species were already identical to those of native leafminers with respect to species richness, idiobiont-koinobiont ratios and the host ranges of the parasitoid species.…”

Species richness and abundance of native leaf miners are affected by the presence of the invasive horse-chestnut leaf miner

“…To our knowledge, the only other convincing case is that of Carvalheiro et al (2008), who observed that an introduced seed feeder affects native communities of seed herbivores in Australia. Leaf miners are ideal models to study apparent competition between alien and native species because, firstly, leaf miners are among the most successful invaders and become particularly abundant compared to native species (Godfray et al 1995;Girardoz et al 2007c); secondly, because leaf miners share many polyphagous natural enemies, particularly parasitoids (Askew 1994;Memmott et al 1994;Morris et al 2004); and, thirdly, because leaf miners are easy to sample and parasitism can be easily assessed using standard methods (Girardoz et al 2007b). The approach used in this study to investigate the effect of C. ohridella on native leaf miners through apparent competition could be applied to other invasive leaf miners, in particular those attacking host plants that are widespread in natural ecosystems.…”

“…Most of these parasitoids are polyphagous, attacking leaf miners belonging to various genera, families and orders (Askew 1994). This high flexibility enables parasitoids to incorporate exotic leaf miners into their host spectrum and, in many cases, may provide substantial control (Godfray et al 1995;Girardoz et al 2007c).…”