Katsuo Tsuda

Biological activity and identification of nucleopolyhedroviruses isolated from Mythimna separata and Spodoptera litura in Japan

We compared the infectivity of two nucleopolyhedroviruses (NPVs), MyseNPV G isolated from Mythimna separata (Walker) (Lepidoptera: Noctuidae) and SpltNPV S isolated from Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae). MyseNPV G was more pathogenic against M. separata than against S. litura. Although SpltNPV S was more pathogenic than MyseNPV G against S. litura, it did not infect M. separata. Restriction endonuclease (REN) analysis of viral genomic DNA revealed that the two NPVs have quite different REN profiles. Based on nucleotide sequences of the coding regions of polyhedrin, lef-8 and lef-9, SpltNPV S was closely related to other SpltNPV isolates, whereas MyseNPV G appeared to belong to the Mamestra NPV group, and was distinct from a Chinese isolate of Leucania (=Mythimna) separata NPV. The potential of MyseNPV G and SpltNPV S to control pest insects is discussed.

Use of a Lower-Volume, Surface Pesticide Spray Conserves Spider Assemblages in a Tea Field

Abstract Since spiders are sensitive to pesticides, the use of lower-volume pesticide sprays that specifically target the plucking surface may help to preserve their assemblages. In this study, we investigated the effect of four pyrethroid pesticides on spider populations in tea (Camellia sinensis) fields when applied using a lower-volume sprayer. Abundance and composition at family level of spiders were assessed before and after treatments. We found that fewer spiders were eliminated when we used a lower-volume sprayer (40 liters/10 ares) rather than a conventional sprayer (200 liters/10 ares) due to the lower-volume treatment only covering the plucking surface (top layer) of the tea plants. These findings indicate that the tea leaf layer plays a good role in sheltering spiders during pesticide application and that the lower-volume treatment that specifically targets the plucking surface can enhance this protection. Therefore, to successfully maintain predatory spiders that prey on tea pests, tea farmers should reduce the volume of pesticides they use and try to restrict the spray to the plucking surface of the plants.

The Effect of Organic Fertilizers and Flowering Plants on Sheet-Web and Wolf Spider Populations (Araneae: Lycosidae and Linyphiidae) and Its Importance for Pest Control

The main goal of this study was to identify the treatment that increases the populations of spiders, which are effective predators in agroecosystems. In 2013 and 2014 the experimental eggplant (Solanum melongena L.) field was two different treatments, organic fertilizers and chemical fertilizer treatment, and in 2014 we surrounded organic fertilizer plots with the flowering plants mealy cup sage (Salvia farinacea Benth.), spearmint (Mentha spicata L.), and basil (Ocimum basilicum L.). Analysis using repeated measures ANOVA revealed significant influences of fertilizer type on the numbers of linyphiid spiders and Collembola in 2013. In 2014, the numbers of Collembola, thrips, and lycosid and linyphiid spider were higher in organic fertilizer with flowering plants treatment comparing with the chemical fertilizer treatment. Moreover, the numbers of Henosepilachna vigintioctopunctata (F.) were significantly lower in the organic fertilizer with flowering plants treatment than in chemical fertilizers treatment. Finally, we expect that Thysanoptera and Collembola were important alternative prey for linyphiid and lycosid spiders and the use of organic fertilizer and flowering plants enhanced the density of these spiders, and may increase their effectiveness in suppressing the populations of H. vigintioctopunctata (F.).