The influence of three populations of Aceria chondrillae on three forms of Chondrilla juncea.
Abstract
The performance of 3 populations of Phytoptus chondrillae G. Can. (Aceria chondrillae), a mite that had been introduced into Australia for the biological control of the weed Chondrilla juncea, was quantified in the glasshouse on forms A, B and C of the food-plant. Form A was the original food-plant for all 3 populations, but while one population had been maintained on form A the other 2 had been maintained on form B, one in the laboratory and one in the field. The original mite population caused extensive gall-formation and reduction of flowering on form A, had a lesser effect on form B and a minor effect on form C. The 2 other populations produced greater effects on both form A and form B than the original population, but attempts to establish one of these on form B in the field in the absence of form A were unsuccessful. These results indicate that the interaction between the mite and its food-plant is very sensitive to changes in growing conditions for the plant. Results pointing to real differences between the 3 populations must therefore be interpreted with caution.