Abstract
The prevalence of obligate parasitic fungi may depend partly on the environmental conditions prevailing in the habitats of their hosts. Ectoparasitic fungi of the order Laboulbeniales (Ascomycetes) infect arthropods and form thalli on the host's body surface. Although several studies report the incidence of infection of certain host species by these fungi, quantitative data on laboulbenialean fungus-host arthropod interactions at the host assemblage level are rarely reported. To clarify the effects of host habitats on infection by ectoparasitic fungi, the incidence of infection by fungi of the genus Laboulbenia (Laboulbeniales) of overwintering carabid beetles (Coleoptera: Carabidae) in three habitats, a riverside (reeds and vines), a secondary forest and farmland (rice and vegetable fields), were compared in central Japan. Of the 531 adults of 53 carabid species (nine subfamilies) collected in the three habitats, a Laboulbenia infection of one, five and one species of the carabid subfamilies Pterostichinae, Harpalinae and Callistinae, respectively, was detected. Three species of fungus were identified: L. coneglanensis, L. pseudomasei and L. fasciculate. The incidence of infection by Laboulbenia was higher in the riverside habitat (8.97% of individuals; 14/156) than in the forest (0.93%; 2/214) and farmland (0%; 0/161) habitats. Furthermore, the incidence of infection by Laboulbenia in the riverside habitat ranged from 0 to 33.3% and differed significantly in the ten microhabitats (riverbank, edge of track, tall reeds, kudzu vines, slope of a hollow, rotten wood, vine reeds, under stones, the shoulder of a terrace and marshy ground) where the carabid beetles overwintered. These results suggest that host habitats and microhabitats are closely associated with successful infection by laboulbenialean fungi.
Highlights
Fungi associated with arthropods are known to have various types of relationships with their hosts
These results suggest that host habitats and microhabitats are closely associated with successful infection by laboulbenialean fungi
As laboulbenialean fungi are easy to detect on the integument of host arthropods (Weir & Hammond, 1997a, b) there are several studies of the incidence of infection of certain hosts by these fungi
Summary
Fungi associated with arthropods are known to have various types of relationships with their hosts (e.g., pathogenic, parasitic, phoretic and mutualistic; Roy, 1994; Vega & Blackwell, 2005; Roy & Cottrell, 2008). The diversity of laboulbeniales depends on the host arthropod guilds and habitats (e.g., predators and forest litter; Weir & Hammond, 1997b). Laboulbenialean fungi are likely to infect hosts that overwinter as adults and have overlapping generations of adults (Weir & Hammond, 1997a, b). The successful infection of hosts by laboulbenialean fungi is likely to depend on the conditions in the microhabitats occupied by the hosts (De. Kesel, 1996b). Carabid beetles have frequently been used as environmental indicators of urbanization and forest fragmentation (Niemelä et al, 2002; Rainio & Niemelä, 2003) Habitats such as grasslands, depend on the habitats and microhabitats in which the host carabids occur. We report differences in the incidence of infection by laboulbenialean fungi of overwintering carabid beetles (Coleoptera: Carabidae) in three habitats in central Japan: riverside, secondary forest and farmland habitats. Overwintering sites of carabid beetles occur within, or near, the habitats they occupy in summer (Yamazaki et al, 1999, 2002, 2003, 2004), which makes overwintering carabid beetles appropriate subjects for investigating the effects of habitats on the incidence of infection by laboulbenialean fungi
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
