SPATIAL DISTRIBUTION OF INSECT SPECIES IN GRANARY RESIDUES IN THE PRAIRIE PROVINCES

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Abstract
The distribution of selected insect species among samples from empty farm granaries in the Prairie Provinces was determined as a guide to determining the number of samples that would have to be collected to obtain reliable estimates of the average number of these species. The number of pest and fungivorous species (adults) per sample followed a negative bionomial distribution for Manitoba data but the number of pest species adults from Sasktachewan followed a Poisson distribution. In Alberta, 39 granary samples contained only one pest species and 507 had none. The number of pests per sample from Manitoba and Saskatchewan and the number of fungivorous species from Manitoba also fitted logarithmic series.The mean number of individuals of each species found in samples (adults or larvae) was always smaller than the variance and the distribution of insect counts followed the negative binomial distribution. Tribolium audax Halstead adults from Alberta also followed a Poisson distribution.The numbers of samples required to provide a predetermined measure of precision for the numbers of species per sample (Manitoba data) and for the numbers of individuals per sample of 15 species (adults or larvae) for each of the three Prairie Provinces were calculated.