Movement of cartap in the rice plant and its insecticidal activity to the sucking insects when applied in the nursery box

Cartap (CTP) concentrations in rice plants were measured by gaschromatography after treatment with CTP granules in a nursery box. Insecticidal activity of the plant to two species of insects, Nephotettix cincticeps and Laodelphax striatellus, was simultaneously tested. It was shown that CTP which was brought into the paddy field with the soil at transplantation was absorbed by the plant, and therefore, a high level of insecticidal activity was maintained for more than two weeks. CTP concentrations calculated from the mortality of the two insects based on the CTP concentration-mortality curves did not correspond with those analyzed by gaschromatography. The later was much higher than the former. One of the reasons for this difference is thought to be the CTP accumulation in the part of the leaves. CTP seemed to be conveyed in two ways in the rice plant. One was in the xylem, but the other was not clear. It took about two days to go up to the leaf from the root by the second way. The insecticidal activity could not be interpreted by CTP concentrations in the xylem exude because these were much lower. CTP in the phloem sap, therefore, seemed to have an important role in insecticidal activity to sucking insects.