SAMPLING SYSTEMS FOR EUROPEAN RED MITE, PANONYCHUS ULMI (ACARINA: TETRANYCHIDAE), EGGS ON APPLE IN NOVA SCOTIA

Abstract

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.

The effect of pyrethroid lambdacyhalothrin applications on the spatial distribution of phytophagous and predatory mites in apple orchards

“…However, all other four species, T. urticae, A. schlechtendali, Z. mali and A. fallacis, displayed smaller values of between-leaf variation than between-tree variation ( Fig. 1 ), as reported by many other authors (Herbert and Butler, 1973;Croft et al, 1976;Mowery et al, 1980;Jones and Parrella, 1984;Zahner and Baumgartner, 1984). This may be because population densities of these species were relative low compared to P. ulmi or because dispersal behavior throughout the season is different.…”

SAMPLING SYSTEMS FOR EUROPEAN RED MITE, PANONYCHUS ULMI (ACARINA: TETRANYCHIDAE): II. EFFECT OF SPUR CLUSTER SIZE ON MITE DISTRIBUTION

“…number of leaves. The effectiveness of this transformation in stabilizing the variance of P. ulmi data has been shown previously (Herbert and Butler 1973). In addition, because of the presence of a few extremely high counts at some cluster sizes, this transformed mean was felt to be a better measure of central tendency than the arithmetic mean.…”