Prey selection by several orb-web spiders

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A) Several characters of spider webs were measured and following index was calculated for the webs of each species :Capture Index = Intensity of adhesiveness X Strength of spirals XStrength of radii X Number of radii * Interval between spirals Eight spider webs are divided into following three groups by the value of the capture index :1) Capture index is very large, so the web can capture very large and heavy prey insects. Of course, small and intermediate sized prey can also be captured by the webs. The webs of Argiope bruennichi, A.amoena and Nephila clavata.2) Capture index is very small, so the web can capture only very small and / or light prey. The webs of Tetragnatha maxillosa, T.praedonia and Leucauge magnifica.3) The value of capture index is intermediate, so the web can small and intermaediate sized prey insects. The webs of Argiope boesenbergi and Metleucauge kompirensis.B) The webs with large capture index captured various sized prey, and very small prey were most abaundant. But, Argiope bruennichi fed larger prey selectively. The webs with small capture index captured small prey, mainly nematocerous insects and mayflies. And the webs of Metleucauge kompirensis, with intermediatecapture index, captured mainly mayflies.So, it was verified that there was the close relationship between the characteristics of the web and its prey.