Competition between Two Species of Mites.: II. Factors Influencing Intensity

Production of webbing, greater fecundity, faster rate of development, and greater ability to thrive on foliage injured by feeding enabled populations of T. telarius to suppress those of P. ulmi on peach foliage in a greenhouse and insectary. However, these inhibitory factors were non-operative in an orchard environment in southwestern Ontario. The tendency of the two species to populate different levels of a host plant, and of P. ulmi to utilize the upper surfaces of leaves more than T. telarius, each decreased the intensity of competition. The suppression of P. ulmi in an insectary or greenhouse was delayed but not prevented by the above factors.