Interrelations Among Ecological Variables in Stored Cereals and Associations with Mycotoxin Production in the...

The incidence of mycotoxins and the interrelations among ecological variables in western Canadian common and durum wheat and barley were determined using 440 railway car samples collected during 1981-83. The 41 Prairie Crop Districts represented by the samples were ranked according to the incidence of fungal infection, mite infestation and other grain quality loss critera and grouped according to climatic subdivisions. Principal component analyses determined linear relationship patterns of ecological variables; ranking of the crop districts was done by Kendall's ranking approximation technique using the first (C₁) and second (C₂) principal components. Only five samples originating from Saskatchewan, Alberta and Manitoba contained ochratoxin A, with levels of 10-51 ppb. None of the samples contained aflatoxins, sterigmatocystin, citrinin, or penicillic acid. All samples containing ochratoxin A had established contamination of species in the Aspergillus glaucus group (10-86% infection level), and Penicillium spp. (20-80% infection level). Most of these samples had low germinability, high fat acidity levels and were infested by stored-product mites including, Acarus siro complex, Lepidoglyphus destructor (Shrank) and Tarsonemus granarius Lindquist. In wheat, the C₁ accounted for 24% of the variability indicating that poorly germinated wheat was associated with the presence of Penicillium , Aspergillus glaucus group, Wallemia sp., and the fungivorous mites, T. granarius and A. siro . The C₂ accounted for 10% of the variability indicating that an increase in free fatty acids was correlated with a high incidence of Aspergillus flavus and A. versicolor . Pronounced C₁ interrelations for wheat were most common in crop districts lying in the Sub-humid Prairie, the northern part of the Dry Belt and the southern part of the Humid regions. Similar relationships for durum wheat and barley were also defined and ranked on maps.