Pathogenicity of Conidiobolus spp. and Basidiobolus ranarum to arthropods co-occurring in leaf litter

A novel method is described for the extraction and presentation of mixed arthropods from litter as targets for potentially pathogenic species of Conidiobolus and Basidiobolus (Zygomycetes: Entomophthorales). All arthropods and test fungi (except C. nr. pumilus from broad leaf litter) were from the same larch (Larix) plantation. For 8 fungus species a bioassay (and repeat), were followed by survivorship comparison tests; Breslow, Logrank (Mantel-Heinszel/Peto) and Wilcoxon (Gehan/Lee-Desau). These were applied to test and control data separately for collembola and mites. Kaplan-Meier plots of Hazard Function were made. Of possible pathogenic effects the most marked was the high mortality of collembola and mites when showered with conidia of C. coronatus. Conidiobolus thromboides (collembola and mites) and C. osmodes (mites only) were associated with enhanced death in one of their two bioassays. Of the other 5 test species, C. adiaeretus and C. iuxtagenitus gave no indication of pathogenicity; nor did C. lamprauges, C. heterosporus and C. pumilus. Ecological implications are briefly discussed.