EVALUATION OF SCREENING METHODS AND SEARCH FOR RESISTANCE IN MUSKMELON, CUCUMIS-MELO L, TO THE 2-SPOTTED SPIDER-MITE, TETRANYCHUS-URTICAE KOCH

Three techniques of screening for resistance in muskmelon, Cucumis melo L., to the twospotted spider mite, Tetranychus urticae Koch, were compared in a laboratory test. Coefficient of variation values were approximately equal for a whole-leaf and floating-disc technique in terms of mean number of mobile mites and eggs, whereas both were substantially lower than that associated with a clip cage. Therefore, both the floating-disc and whole-leaf technique are indicated as superior techniques for isolating mites on melon leaves in screening trials. In greenhouse mass screening trials (using a whole-leaf technique), many lines exhibited lower densities of adult twospotted spider mites compared with a standard commercial variety 'Perlita'. Melon lines 'BUS', 'CHI', Plant Introduction (PI) 164343 and PI 179895 exhibited resistance in greenhouse mass screenings and had significantly lower numbers of female mites per leaf in more intensive greenhouse screenings. PI lines 124101, 124431, 125896 and 125956, which expressed resistance in greenhouse mass screenings, also had low densities of mites in field screening.