The bean bug, Riptortus pedestris, is one of major hemipteran pests against the soybean, Glycine max in Korea. In previous study, it was suggested that water-taking in the first instar nymphal stage of R. pedestris is certainly necessary for successful ecdysis and their survival. To investigate water-taking behavior of the first instar nymphs of R. pedestris on plant, electrical penetration graphic patterns were analysed while R. pedestris fed on the napa cabbage leaf, Brassica rapa subsp. pekinensis by using EPG system. In the result, a X-waveform was dominantly observed for average 42.0 min out of total recording time (120 min). There was significant positive correlation (r = 0.457, P = 0.000452, n = 55) between body weight increase and cumulative durations of X-waveform. In addition, histological observation of cross-sections indicated that stylet tip in the plant tissue during X-waveform period is located nearby xylem cells, suggesting that X-waveform is closely related to xylem sap feeding behavior of R. pedestris in plant.

• Jum Rae Cho(Crop protection division, National Institute of Agricultural Sciences, RDA)
• Gwan-Seok Lee(Crop protection division, National Institute of Agricultural Sciences, RDA)
• Jin Kyo Jung(Crop Cultivation and Environment Research Division, National Institute of Crop Science, RDA)
• Bo Yoon Seo(Crop protection division, National Institute of Agricultural Sciences, RDA)