Aspects of the relationship between Panonychus ulmi (Koch) and Tetranychus McDanieli McGregor in Simple Ecosystems (Acarina: Tetranychidae)

ABSTRACT

Observations on the effects of competition between Panonychus ulmi (Koch) and Tetranychus mcdanieli McGregor population development were studied on Red Delicious apple trees grown in a greenhouse. It was shown that competition for the utilization of common resources does exist between mixed populations. From infestation ratios ranging from 2:1 to 1:5, T. mcdanieli female counts were comparable on both leaf surfaces, whereas P. ulmi female counts were related to the initial T. mcdanieli release density. The interaction between host plant and both spider mite species and the propensity of T. mcdanieli females to emigrate is discussed in terms of their influence on the outward manifestations of competition under greenhouse conditions.