Abstract
Hesperomyces virescens is an ectoparasite of some Coccinellidae, which until the mid-1990s was relatively rarely only reported from warm regions in various parts of the world. Analysis of the host and distribution data of H. virescens recorded in the Western Palaearctic and North America reveals several trends in the occurrence and abundance of H. virescens: (1) it has recently been much more frequently recorded, (2) most of the recent records are for more northerly (colder) localities than the early records and (3) the recent records are mostly of a novel host, the invasive harlequin ladybird (Harmonia axyridis). While in North America H. virescens is almost exclusively found on H. axyridis, all European records of this association are very recent and still less numerous than records of Adalia bipunctata as a host. However, based on a relatively few published cases of the H. axyridis-H. virescens association in Europe and the case described in this paper, it is clear that the harlequin ladybird is currently the main host of this parasite. These changes in the abundance and geographical distribution of H. virescens are probably linked to some features of H. axyridis, such as its abundance, multivoltinism with overlapping generations, high level of promiscuity and overwintering in mass aggregations. The occurrence of these features in one species may make it especially suitable for H. virescens and other parasites that require close contact of host individuals for efficient transmission. Indeed, some of the data indicate that parasites other than H. virescens, like the podapolipid mite Coccipolipus hippodamiae and allantonematid nematodes of the genus Parasitylenchus may also heavily parasitize H. axyridis. We hypothesize that the acquisition of H. axyridis as a host by H. virescens, C. hippodamiae and Parasitylenchus spp. may have further consequences for the abundance and distribution of these parasites, including the expansion of their ranges to other continents colonized by invasive populations of this ladybird and areas in Asia where H. axyridis is native.
Highlights
Fungi of the order Laboulbeniales are obligate ectoparasites of insects and other arthropods, but beetles (Coleoptera) are their most common hosts (Weir & Hammond, 1997; Majewski, 2008)
Compact thalli of Laboulbeniales attach to the cuticle of the host by a melanized terminal part of the basal cell called the foot
H. virescens is recorded infecting a wide array of ladybird hosts in many parts of the world, including North and South America, the Caribbean, Borneo, Melanesia, Japan, Near East, North Africa and Europe (Thaxter, 1931; Santamaria et al, 1991; Ceryngier et al, 2012)
Summary
Fungi of the order Laboulbeniales are obligate ectoparasites of insects and other arthropods, but beetles (Coleoptera) are their most common hosts (Weir & Hammond, 1997; Majewski, 2008). H. virescens is recorded infecting a wide array of ladybird hosts in many parts of the world, including North and South America, the Caribbean, Borneo, Melanesia, Japan, Near East, North Africa and Europe (Thaxter, 1931; Santamaria et al, 1991; Ceryngier et al, 2012). One of the reported hosts of H. virescens is the harlequin ladybird, Harmonia axyridis (Pallas), an invasive species of Asiatic origin that from the late 1980s onwards rapidly expanded its range, at the beginning in the United States and currently in North and South America, Europe and Africa (Brown et al, 2011). Lands, Germany and several Belgian localities (Steenberg & Harding, 2010; De Kesel, 2011; Haelewaters & De Kesel, 2011; Haelewaters et al, 2012) This fungus is not reported attacking H. axyridis within its native (Asiatic) range, it is reported infecting Coccinula crotchi (Lewis) and C. sinensis (Weise) in the eastern part of its range (Japan) (Ceryngier et al, 2012). We speculate on potential consequences of this novel association for the further spread of the parasite
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
