Abstract: This paper focuses on studying the influence of herbicides on the food intake of Ummeliata insecticeps(Bosenberg et Strand) by a novel quantitative method-the fluorescence labeling method. Europium, the lanthanide chosen for the experiment, was dissolved in the soil and then absorbed by the rice plants. Sogatella furcifera eats the plants and U. insecticepspreys on S. furcifera for food. Thus, by applying a series of chemical analytical methods of extracting and invert extracting on the tested fly louse and spider samples, the food intake of  U. insecticepscould be known. The results showed that each surviving spider individual sprayed with Simetryne preyed on 1.784 S. furcifera individuals per day over the course of 12 days. If sprayed with Starane, spiders preyed on 2.678 S. furcifera individuals/d, and with Gallant S, 2.856 individuals/d, on average. The individual food intakes of the three test groups were all less than that of the control group, which preyed on 3.321 S. furcifera individuals/d. The curves of the food intakes of the spiders in the different groups are all inverted parabolas, which can be fitted by quadratic equations. If mortality is taken into account, for the first 8 days after the application of herbicides, the population food intakes of the test groups are all much less than that of the control group. The average predatory ratios of the three test groups in the 2nd day, the 5th day and the 8th day are 52.11%, 36.45% and 50.27% of the control group's population food intake, respectively. In the 12th day, however, the population food intake of the test groups is 131.84% of that of the control group. It could be concluded that all of the herbicides tested do harm to the spiders' food intake capacity within 8 days of exposure. Therefore, it is unadvisable to apply herbicides when the paddy field is rife with pests because the herbicides would weaken the spiders' control over the pests. It is also unadvisable to apply herbicides during the harvest season because the spiders migrate at this time and the lethality of the herbicides will disturb the rebuilding of the spider communities.

Key words: Ummeliata insecticeps, Sogatella furcifera, lanthanide, fluorescent tracking, herbicides, food intake