Abstract
The development and oviposition of the Kanzawa spider mite, Tetranychus kanzawai KISHIDA on leaves of five grape cultivars in an insectary, and the field population trends of the mite on four cultivars treated with permethrin and carbaryl were studied. High developmental success was observed on Muscat Bailey A (Vitis labrusca×V. vinifera×V. linsecumii) and Delaware (V. labrusca×V. vinifera×V. aestivalis) cultivars. On Kyohou (V. vinifera×V. labrusca), one quarter of tested larvae developed to adults. Only 2% of larvae developed on Muscat of Alexandria (V. vinifera) and no developmental success was observed on Neo Muscat (V. vinifera) and Campbell Early (V. labrusca×V. vinifera). Total egg production on Muscat Bailey A and Kyohou was larger than on Delaware, but no significant difference detected between Kyohou and Delaware. The population density of T. kanzawai also varied considerably between grape cultivars and spray practices. On permethrin- and carbaryl-sprayed vines, mite populations increased about 20 days after insecticide application. The cumulative numbers observed during the survey on insecticide-sprayed leaves were highest on Muscat Bailey A but remained low on Campbell Early. Kyohou and Delaware showed intermediate population densities. No population growth was observed on Neo Muscat. In non-sprayed controls, the mite populations remained at low levels of below three adult females per leaf on all cultivars.
