Spider predation on a mirid pest in Japanese rice fields |
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Authors: | Tetsuya Kobayashi Mayura Takada Shun Takagi Akira Yoshioka Izumi Washitani |
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Institution: | aNational Institute of Agrobiological Sciences, Owashi, Tsukuba, Ibaraki 305-8634, Japan;bDepartment of Life Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan;cGraduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan |
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Abstract: | Spiders are common generalist predators, and understanding their potential in biological control is important for the development of integrated pest management programs. In this study, predation by three groups of spiders on the mirid bug Stenotus rubrovittatus (Hemiptera: Miridae) in rice paddies was investigated using DNA-based gut-content analysis. A laboratory feeding study revealed that the detection half-lives of bug DNA in the spider gut at 25 °C was 3.4 days for Lycosidae and 1.5 days for Tetragnathidae. Individual spider predation on the mirid bug was investigated by detecting DNA of prey in field-collected spiders. In total, 1199 spiders were assayed from three spider groups: Pirata subpiraticus (Lycosidae), Tetragnatha spp. (Tetra-gnathidae), and Pachygnatha clercki (Tetra-gnathidae), which each differ in their preferred microhabitat as well as their predatory habits. Detection rates of prey DNA in spiders increased significantly with the density of prey across all spider groups. P. subpiraticus and Tetragnatha spp. predation showed a better fit to a saturated response curve to increasing prey density, while P. clercki showed a simple linear relationship with prey density. Densities of alternative prey species did not affect the detection rates of mirids. These results suggest that predation on pests by generalist predators in an agroecosystem is affected not only by prey abundance but also by predator preference for specific prey. Predator preference is therefore an important factor to consider when estimating the role of natural enemies as biological control agents. |
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Keywords: | Biological control Generalist predator Gut-content analysis Integrated pest management Predator&ndash prey interactions Rice |
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