Abstract
The feeding behaviour of Nephotettix cincticeps, N. virescens and N. nigropictus on suitable and unsuitable plants was investigated through an analysis of honeydew composition. Although a certain amount of honeydew was excreted on both kinds of plants, there was less sugar content and no sucrose in the honeydew from unsuitable plants. The influence of the extract from both kinds of plants on the survival and feeding behaviour of the three Nephotettix spp. was investigated. The water soluble extract of the unsuitable plant caused high mortality in the three Nephotettix spp. while that of the suitable plant, 'Nihonbare', did not. The basic fraction of the unsuitable plant extract resulted in high mortality. The acidic and neutral fractions also caused high mortality in N. virescens. The amphoteric fraction of unsuitable plants was found to be beneficial for their survival. Feeding behaviour recorded on an electric measurement device showed that the ingestion pattern duration of the three Nephotettix spp. became shorter when the basic fraction was added to the sucrose solution as compared with sucrose solution alone or with amphoteric fraction added. A special feeding pattern which was supposed to be a phloem ingestion pattern was recorded when N. virescens fed on sucrose solution augmented by the amphoteric fraction.
