An inquiry into the fungal diversity associated with the galls formed by Pemphigus betae Doane

Abstract

Leaves affected by galls induced by the aphid Pemphigus betae were collected from a Populus balsamifera tree located near the community garden on the campus of Lakehead University Thunder Bay. Out of the galls that were collected, 100 were selected to examine the fungal diversity found within. Inner tissue samples were taken from each gall and inoculated onto 2% malt extract agar in Petri dishes. After pure cultures were obtained through isolation, the fungal taxa were identified. The fungal diversity found within the galls sampled, displayed an ecological and taxonomic pattern that varied from gall to gall. One hundred and ninety three isolates representing 43 different taxa were found. The most common species isolated from the galls were Cladosporium cladosporioides (from 54% of galls), Verticillium lecanii (from 26% of galls), Penicillium simplicissimum (from 21% of galls), Fusarium sp. 1 (from 20% of galls) and Penicillium brevicompactum (from 18% of galls). Ecologically, most fungi represented typical saprophytic and phylloplane species which tend to be ubiquitous and cosmopolitan, while a few represented entomopathogenic species, and some represented plant pathogenic species. Further analysis will be needed to understand the full diversity found within the galls. This can be done through an expansion in the number of samples collected and isolated from, and from multiple host trees over a larger geographic area.