Parasites of Harmonia axyridis: current research and perspectives

Abstract

Harmonia axyridis (Coleoptera: Coccinellidae) has been introduced widely for biological control of agricultural pests. Harmonia axyridis has established in four continents outside of its native range in Asia and it is considered an invasive alien species (IAS). Despite a large body of work on invasion ecology, establishment mechanisms of IAS and their interactions with natural enemies remain open questions. Parasites, defined as multicellular organisms that do not directly kill the host, could potentially play an important role in regulating host populations. This study presents a review of the parasites of H. axyridis, discussing their distributions and effects on host populations across the host's native and invasive range. These parasites are: Hesperomyces virescens Thaxt. fungi, Coccipolipus hippodamiae (McDaniel and Morrill) mites, and Parasitylenchus bifurcatus Poinar and Steenberg nematodes.

Predators and parasitoids of the harlequin ladybird, Harmonia axyridis, in its native range and invaded areas

“…No empirical confirmation of this exists so far, but the finding of Sluss (1968) that the successful development of D. coccinellae was prevented in microsporidia-infected ladybirds (Hippodamia convergens Guérin) makes this hypothesis plausible. It should also be tested whether other pathogens and parasites of H. axyridis, especially the nematode Parasitylenchus bifurcatus Poinar and Steenberg (Harding et al 2011;Poinar and Steenberg 2012;Haelewaters et al 2017), can interfere with D. coccinellae larval development.…”

“…Acquisition of new enemies by H. axyridis in the invaded areas does not only apply to parasitoids. True parasites, such as the mite Coccipolipus hippodamiae (McDaniel and Morrill), the nematode Parasitylenchus bifurcatus, and the fungus Hesperomyces virescens Thaxter, are also believed to have been acquired by the populations of the harlequin ladybird in the invaded range (Ceryngier and Twardowska 2013;Haelewaters et al 2016Haelewaters et al , 2017). …”

“…The success of H. axyridis as an invader is often attributed to weak control of its populations by natural enemies, with the enemy release hypothesis (ERH) usually being quoted to explain this low level of biological control (Roy et al , 2011aBerkvens et al 2010;Firlej et al 2012;Comont et al 2014;Haelewaters et al 2017). ERH states that an alien species invading a new geographic range will be less affected by natural enemies compared to native species, leading to population build-up of the alien species in its invasive range.…”

“…The group of enemies of H. axyridis, in which sublethal fitness effects prevail over direct killing, i.e. multicellular true parasites, has recently been reviewed by Haelewaters et al (2017). Here, we (1) compile the available data on the predators and parasitoids of H. axyridis in its native range and invaded areas, (2) analyze the importance of these enemies in limiting populations of H. axyridis, (3) discuss enemy release and enemy acquisition by invading H. axyridis, and (4) suggest future research directions concerning this topic.…”

First report of nematodes Parasitylenchus bifurcatus Poinar & Steenberg, 2012 parasitizing multicolored Asian lady beetle Harmonia axyridis (Pallas, 1773) in Slovenia

“…However biocides can be used for the species control in household environments which are not intended for crop production. Therefore researchers have allocated their efforts in the search of natural enemies of multicolored Asian lady beetle that could reduce their numbers (Raak-van den Berg et al, 2014 (Majerus et al, 1999, Raak-van den Berg et al, 2014, Haelewaters et al, 2017.…”