Resistance to the two-spotted spider mite, Tetranychus urticae (Koch), in New Guinea Impatiens

Twenty-seven Impatiens lines were screened and scored for resistance to the two-spotted spider mite, tested for leaf cuticle amount, crossed, and selfed. Progenies of successful matings were subjected to feeding preference and score rating tests. Seventeen lines from the parents and their progenies were selected and tested for oviposition, life cycle of the pest, feeding preference, leaf pH preference, and for size of eggs, females, and males of the mites;Considerable differences were found among these lines in all tests except the reciprocal hybrid evaluation. Leaf cuticle appeared to have some influence on development of the mite population;The resistance to the mites in Impatiens does not seem to be related to a single mechanism but to many mechanisms, and the genetic control of resistance is no doubt complex;Attention in future studies should be focused on the twin lines, \u277729-8\u27 and \u277729-9\u27, as sources of genes for resistance to the two-spotted spider mite