Presence-absence sampling for Panonychus ulmi (Koch, 1836) (Acarina: Tetranychidae) in apple trees

René R. Vargas M.1

The presence-absence sampling method was validated for P. ulmi in apple trees. To the binomial function, the parameters "a" and "b" of Taylor's Power law were incorporated, to describe its aggregation behavior and calculate the proportion of infested samples P^(1). The regression of the expected against the observed P (1) values was significant and explained 95% of the variation. Its use is recommended for a rigorous quantification of the patterns of the spacial aggregation of different arthropods.

1 Subestación Experimental Control Biológico La Cruz (INlA), casilla 3, La Cruz, Chile.