title: Invasive harlequin ladybird carries biological weapons against native competitors.
abstract: Invasive species that proliferate after colonizing new habitats have a negative environmental and economic impact. The reason why some species become successful invaders, whereas others, even closely related species, remain noninvasive is often unclear. The harlequin ladybird Harmonia axyridis, introduced for biological pest control, has become an invader that is outcompeting indigenous ladybird species in many countries. Here, we show that Harmonia carries abundant spores of obligate parasitic microsporidia closely related to Nosema thompsoni. These microsporidia, while not harming the carrier Harmonia, are lethal pathogens for the native ladybird Coccinella septempunctata. We propose that intraguild predation, representing a major selective force among competing ladybird species, causes the infection and ultimate death of native ladybirds when they feed on microsporidia-contaminated Harmonia eggs or larvae.
authors.affiliation: Institute of Phytopathology and Applied Zoology, Heinrich-Buff-Ring 26-32, Justus-Liebig-University of Giessen, D-35392 Giessen, Germany. andreas.vilcinskas@agrar.uni-giessen.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
authors.forename: Kilian
authors.initials: K
authors.lastname: Stoecker
authors.forename: Henrike
authors.initials: H
authors.lastname: Schmidtberg
authors.forename: Christian R
authors.initials: CR
authors.lastname: Röhrich
authors.forename: Heiko
authors.initials: H
authors.lastname: Vogel
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000469:parasitology* / Q000502:physiology*; D020387:Food Chain; D006434:Hemocytes / Q000469:parasitology; D006458:Hemolymph / Q000469:parasitology; D058865:Introduced Species; D016818:Nosema / Q000502:physiology* / Q000648:ultrastructure