Fungal communities forming associations with plant roots have generally been described as ranging from symbiotic to parasitic. Disruptions to these associations consequently can have significant impacts on native plant communities. We examined how invasion by Vincetoxicum rossicum, a plant native to Europe, can alter both the arbuscular mycorrhizal fungi, as well as the general fungal communities associating with native plant roots in both field and woodland sites in Southern Ontario. In two different sites in the Greater Toronto Area, we took advantage of invasion by V. rossicum and neighbouring uninvaded sites to investigate the fungal communities associating with local plant roots, including goldenrod (Solidago spp.), wild red raspberry (Rubus idaeus), Canada anemone (Anemone canadensis), meadow rue (Thalictrum dioicum), and wild ginger (Asarum canadense). Fungi colonizing roots were characterized with terminal restriction fragment length polymorphism (T-RFLP) analysis of amplified total fungal (TF) and arbuscular mycorrhizal fungal (AMF) ribosomal fragments. We saw a significant effect of the presence of this invader on the diversity of TF phylotypes colonizing native plant roots, and a composition shift of both the TF and AMF community in native roots in both sites. In native communities invaded by V. rossicum, a significant increase in richness and colonization density of TF suggests that invaders such as V. rossicum may be able to influence the composition of soil fungi available to natives, possibly via mechanisms such as increased carbon provision or antibiosis attributable to unique root exudates. ReSeARCh ARtICle Launched to accelerate biodiversity conservation A peer-reviewed open-access journalCindy L. Bongard et al. / Nature Conservation 4: 55-75 (2013) 56

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Seasonal trends of the percentage of nitrogen, phosphorus, and potassium were measured in the foliage of apple trees infested with the European red mite, Panonychus ulmi (Koch), at four population levels created by the action of predators and/or chemical treatment.It was shown that by early September the concentrations of these nutrients; particularly nitrogen, were significantly depressed by high P. ulmi populations.

The relative densities of phytophagous and predacious mites within mature apple trees were examined. The eggs of phytophagous mites Aculus schlechtendali (Nal.) and Panonychus ulmi (Koch) were more numerous in the lower position of the tree while the reverse was true for the predacious mite Zetzellia mali (Ewing) and its eggs.

Can. Ent. 105: 1519-1523 (1973) A study was conducted in a mature apple orchard in Nova Scotia to compare the density of eggs of the European red mite, Panonychus ulmi (Koch), over the whole tree to their density on a selected area using a random selection and standard selection technique. Both methods provided nearly equivalent estimates of population densities for generations 2 and 4 but not for generation 3. The population estimates based on sampling from the selected area overestimated the whole tree population.Optimum allocation of sampling resources may be obtained by sampling a small number of clusters from each of a large number of trees.