Prevalence and association of the laboulbenialean fungus Hesperomyces virescens (Laboulbeniales: Laboulbeniaceae) on coccinellid hosts (Coleoptera: Coccinellidae) in Kentucky, USA

Abstract

Abstract. The laboulbenialean fungi occur throughout the world and are closely associated with a range of arthropods, including many coleopteran hosts. Throughout the summer of 2004, coccinellids were collected from a Bluegrass savanna woodland ecosystem, dominated by blue ash Fraxinus quadrangulata and Chinkapin Oak Quercus muehlenbergii, and the adults were examined for the presence of Hesperomyces virescens using binocular and scanning electron microscopy. Over 80% of adult Harmonia axyridis, a species previously reported as having a persistent association with the fungus, were infected. No significant differences were observed in incidence on male and female hosts, however, the distribution of fungus differed between sexes. Female H. axyridis had a greater percentage of infection on their elytron compared to other parts of their body whilst male infection was concentrated around their elytra, legs and abdomen. Although infection rates were significantly lower, we report, for the first time, the presence of this fungus on the hosts Cycloneda munda, Brachiacantha quadripunctata and Psyllobora vigintimaculata. This is the first study documenting the incidence of this insect-associated fungus with these native coccinellids of North America. In the samples collected from the Bluegrass savanna, two species (Coleomegilla maculata and Hyperaspis signata) were not infected by this fungus.

Laboulbeniales (Ascomycota) of the Boston Harbor Islands I: Species Parasitizing Coccinellidae and Staphylinidae, with Comments on Typification

“…Of these, C. septempunctata, C. munda, and H. convergens have been previously observed with H. virescens in the US (Harwood et al 2006, Thaxter 1931 On 2 slides (FH 00313516 and FH 00313517) taken from H. axyridis, we found thalli with long median outgrowths of the perithecial tip together with thalli having short median outgrowths. This observation has also been made on Adalia bipunctata (L., 1758) from French Guyana (Bernardi et al 2014) and Cycloneda sanguinea sanguinea (L., 1763) from Guatemala (this study).…”

Harmonia axyridis (Coleoptera: Coccinellidae) as a host of the parasitic fungus Hesperomyces virescens (Ascomycota: Laboulbeniales, Laboulbeniaceae): A case report and short review

“…This difference indicates that an important but not the only way in which H. virescens is transmitted between hosts is during mating. The importance of mating for the transmission of the parasite is reported by other researchers (Welch et al, 2001;Garcés & Williams, 2004;Harwood et al, 2006a;Riddick, 2006) along with other kinds of direct contact between hosts, especially when they aggregate during winter (Riddick & Schaefer, 2005;Nalepa & Weir, 2007).…”

Forgotten natural enemies: Interactions between coccinellids and insect-parasitic fungi

“…Smaller numbers are thought to be associated with other insect orders (Blattodea, Dermaptera, Diptera, Hemiptera, Hymenoptera, Isoptera, Orthoptera and Thysanoptera) and also from noninsect hosts (Acari and Diplopoda). These intriguing fungi are obligate ectoparasites that infect many coccinellids (Thaxter, 1931;Nalepa & Weir, 2007) occurring from the tropics to the sub-Antarctic on both terrestrial and aquatic hosts (Santamaria, 2001;Harwood et al, 2006).…”

“…Interestingly, our knowledge of the physiological and ecological susceptibility of coccinellids to the laboulbenialean fungus H. virescens is just the opposite. Less is known about the physiological host range of H. virescens attacking coccinellids compared with its known ecological host range (Harwood et al, 2006).…”

“…In a study of the laboulbenialean fungus H. virescens on coccinellids in Kentucky, USA, Harwood et al (2006) found that 82.3% of H. axyridis were infected compared with only 4.7, 4.2 and 2.5% of Psyllobora vigintimaculata Say (Coleoptera: Coccinellidae), Brachiacantha quadripunctata (F.) (Coleoptera: Coccinellidae) and Cycloneda munda (Say) (Coleoptera: Coccinellidae), respectively. Those authors did not recover this ectoparasitic fungus from C. maculata or Hyperaspis signata (Oliv.)…”