Distribution of Phytophagous and Predacious Mites on Apple Trees in Nova Scotia

Abstract

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.

Sampling mites in almonds: I. Within-tree distribution and clumping pattern of mites with comments on predator-prey interactions

“…The lack of a significant difference between quadrants within the tree is encouraging and indicates that sampling by random selection of leaves from around the tree is unlikely to result in a biased estimate of spider mite density, at least during the period of May to September. Herbert and Butler (1973) likewise reported significant between-tree differences and did not find quadrant differences when examining the distribution of the European red mite, Panonychus ulmi (Koch), the apple rust mite, A. schlechtendali (Nal. ), and the predaceous mite, Zetzellia mali (Ewing), on apple trees.…”

“…8 years old), although mature, and therefore not having a wide within-tree microclimatic range. The apple trees used by Herbert and Butler (1973), on the other hand, were 25 years old and possibly more architecturally complex. The difference may also be due to the architecture of various tree species.…”

“…The much lower pattern of clumping for M. occidentalis is apparent because of the lower values for both the 'a' and 'b' coefficients ( figure I.1C). Although Croft et al (1976) and Herbert and Butler (1973) present Taylor's coefficients for the mite species examined in their studies, their coefficients were based on what each called a per tree sample unit basis and therefore cannot be com pared directly with our per leaf sample unit estimates. Wilson et al (1983a) Predator efficacy Figure 1.2 shows the estimated proportion infested-density response curves for spider mites with and without M. occidentalis, and the direction that the curve would take due to mortality and dispersal.…”

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

“…), and two positions (inner and outer) giving 16 subdivisions within each tree. This method is further described by Herbert and Butler (1973). The "sample area", as designated by Sanford and Herbert (1970), consisted of all quadrants in the outer position of the lower level, i.e.…”