Abstract:Trapping tests for melon thrips, Thrips palmi, were carried out using 17 colored resin sheets, 8 LED lights, and 2 types of plate. Among the colored resin traps, more thrips were captured by resin with a peak spectral reflectance between 481 and 523 nm. Among the 8 LED light traps covered with a diffuser, more thrips were captured by LED traps with peak wavelengths of 500 or 525 nm. When the LED light traps were covered by a transparent acrylic plate, the 470-nm LED trap captured as many thrips as the 525-nm LED trap, and both produced the highest capture rate. In an experiment that combined LED traps with one of three wavelengths 470, 500, or 525 nm and either a diffuser or a transparent plate, the 470-nm LED trap captured fewer thrips than the other combinations, and the 470-nm trap covered by a diffuser captured significantly fewer thrips than the same trap covered by a transparent plate. Significantly higher captures were obtained using 500-or 525-nm LEDs covered by transparent plates. Thus, melon thrips were stably attracted to light at wavelengths from 500 to 525 nm.
Five phytoseiid mite species: Phytoseiulus persimilis Athias-Henriot, Neoseiulus californicus McGregor , Neoseiulus womersleyi Schicha , Amblyseius eharai Amitai and Swirski, and Euseius sojaensis Ehara Acari: Phytoseiidae were collected from commercial Japanese pear orchards in Shizuoka Prefecture. To evaluate the suppressive effect of generalist phytoseiid species on the spider mite Tetranychus kanzawai Kishida Acari: Tetranychidae , we compared four treatments E. sojaensis release, A. eharai release, synthetic pyrethroid application, and no-release performed in a greenhouse. These treatments were conducted when T. kanzawai densities were low, and pine pollen was provided as alternative food for predatory mites in all treatments. At late June, the peak densities of T. kanzawai were significantly low in E. sojaensis release and in no-release compared with in pyrethroid application and in A. eharai release. The dominant phytoseiid species in E. sojaensis release and in no release was E. sojaensis. After July, however, E. sojaensis densities became lower in E. sojaensis release as well as no-release, and thus T. kanzawai densities became higher in all treatments at early August. These results suggest that conservation and augmentative release of E. sojaensis prior to T. kanzawai population increase, might suppress the outbreak of this spider mite in Japanese pear orchards until early summer.
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