Natural occurrence of entomophthoralean fungi pathogenic to collembolans.

Abstract

The aim of this study was to assess the natural occurrence of fungi from the order Entomophthorales (Zygomycetes) pathogenic to a range of collembolan species. A total of 11,709 collembolans representing a total of 15 species from all three subclasses within Collembola were collected and incubated. Infection with Neozygites-like spp. (Entomophthorales) was recorded in the two subclasses, Arthropleona and Symphypleona. The morphology of the primary conidia of the Neozygites-like fungi infecting collembolans showed a high degree of variation in shape and size, and the fungi were divisible into five groups. One group consisted of Neozygites sminthuri, while the other four groups, while still closely resembling the genus Neozygites, did not fit within the description of any known species and were preliminarily designated Neozygites sp. nov. 1 to 4. Neozygites sp. nov. 1, infecting Sphaeridia pumilis, was observed to form globular secondary conidia, which have not been observed before within the genus Neozygites. A formal species description needs, however, yet to be performed. The infection was mainly found in species from the subclass Symphypleona, where two new host genera for Neozygites, Deuterosminthurus and Sphaeridia, were recorded. However, the prevalence of Neozygites spp. was low, up to 10% in S. pumilis, 6% in Sminthurus viridis, and below 1% in Deuterosminthurus sulphureus. Infection with an obligatory entomopathogenic fungus was for the first time well documented within the subclass Arthropleona, where specimens of Orchesella cincta and Orchesella villosa sporulated with a N. sminthuri-like fungus. Additionally, infection with the facultative pathogen Conidiobolus coronatus was recorded from several hosts representing both the subclass Arthropleona (Isotoma anglicana and O. cincta) and the subclass Symphypleona (Dicyrtoma sp. and S. viridis). For most species the prevalence of C. coronatus resembled that of Neozygites spp. and did not exceed 8.8%. The only exception was Dicyrtoma sp., for which the only associated entomophthoralean fungus was C. coronatus, where the prevalence reached 17.8% infection.