Sampling efficiency of methods to estimate the number of Nephotettix cincticeps Uhler in the resting paddy field

Numbers of adults and fifth instar nymphs of the green rice leafhopper, Nephotettix cincticeps UHLER were estimated by the release-and-recapture method in early June in resting paddy fields, where gramineous and leguminous weeds grew. A field, 424.8m2 in area, was divided into 24 sub-areas and capture with sweep-net, marking and release were repeated for three consecutive days at each of the 14 sub-areas. The number of adults in this paddy field was estimated as about 32 per 1m2, using BAILEY'S triple-catch equation. Dividing the number of leafhoppers in the field captured by 10 strokes of the sweep-net by the number of leafhoppers estimated by release-and-recapture method, the sampling efficiency (the rate of capture) of the sweep-net method was obtained as about 0.10, and its variance seemed to be relatively small. The sampling efficiency of the sweep-net method was lower for female adults than for male adults, and that for fifth instar nymphs was lower than for adults. Concurrently, leafhoppers were also collected with a suction machine to cover 1m2 at each of 10 sub-areas, where release of insects was not conducted, and its sampling efficiency was calculated as did for the sweep-net method with the result that the suction machine could capture adult so both sexes with almost the same rate, and capture relatively large number of fifth instar nymphs compared with the sweep-net method.