Hibernation of the Kanzawa Spider Mite, Tetranychus kanzawai Kishida (Acarina: Tetranychidae) and Its Predators in Grapevine Glasshouses

Abstract

Overwintering sites and source of population growth after hibernation of Tetranychus kanzawai and its predators in grapevine glasshouses were surveyed at Ichinomiya, Okayama, and Akitsu, Hiroshima. T. kanzawai overwintered as adult female, on fallen grape leaves and dead weeds, and in bark crevices, straw mulch and surfaces oil. The overwintering predators collected in the glasshouses consisted of 4 species of predacious mites: Amblyseius barkeri (Hughes), A. longispinosus (Evans), A. tsugawai Ehara AndAgistemus exsertus Gonzalez-Rodrigues, And a spider: Achaearanea tepidariorum (C. Koch). They hibernated mainly on litter but were not found in bark crevices of the vines. After the room temperature was raised by heating or heat retention treatment, T. kanzawai was collected in bark crevices and straw mulch in a glasshouse where the heat retention treatment had been applied 8 days before the survey. In other heated houses, mites were scarcely found on grapevines. Its population growth was observed on weeds and undergrowth. When potted grapevines inoculated with hibernating T. kanzawai were exposed to a temperature of 20°C early in March, the mites disappeared or died on the vines within 22 days. An adult female mite and its progeny were found on weeds. These results indicate that the overwintered generations of T. kanzawai are unable to reproduce on grapevines. The source of early mite infestation on grapevines may be represented by the migrants grown on the weeds or undergrowth in the houses. © 1987, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.