A model of the plant‐to‐plant movement of aphids II. Estimation of parameters and the application

Abstract

Summary It was shown in the previous report that the statistical model of the plant‐to‐plant movement of aphids could be fitted well to the actual population of barley aphids (Shiyomi, 1967). To examine validity of the model, results of the further experiments were analysed and the methods of estimation of parameters were given in this paper. Comparing the estimates of the parameters obtained by the moment method with those obtained by the maximum likelihood method, the estimates from the latter method were somewhat precise. The theoretical frequency distributions calculated from the model were fitted very well to the observed ones. The model was reexamined with reference to the results obtained byItô (1954, 1960). When the distance between plants was less than 4.5 cm, the farther was the distance between plants, the smaller was the rate of the plant‐to‐plant movement of aphids. When the distance was greater than 4.5 cm, however, the rate of the plant‐to‐plant movement was independent of the distance. This result is similar to that ofItô.