Quantitative evaluation of predation by spiders on the green rice leafhopper, <i>Nephotettix cincticeps</i> Uhler, by a sight‐count method

Abstract

Summary A sight‐count method for evaluation of predation by spiders on the green rice leafhopper, Nephotettix cincticeps was proposed and its applicability was tested under natural conditions. The number ( n ) of leafhoppers preyed on by spiders per rice hill per day was estimated by the formula: urn:x-wiley:14383896:pope0187:equation:pope0187-math-0001 where F is the frequency of predation observed per hill: P is given by dividing the time spent feeding on prey by 24 hours; and C refers to the total amount of feeding activity expressed in terms of the activity during the standard time interval. The total number ( N ) of prey attacked during the specified period can be given as follows: urn:x-wiley:14383896:pope0187:equation:pope0187-math-0002 With this method, the role of paddy‐inhabiting spiders, Lycosa pseudoannulata, Oedothorax insecticeps, Tetragnatha spp, and Enoplognatha japonica , as predator of N. cincticeps was evaluated with reference to life tables of the prey. The advantages and limitation of the sight‐count method were discussed as compared with other methods so far proposed.