Food Intake Capacity And Starvation Endurance Of Ummelita Insecticeps

It is a patent technique originated by faculty in our laboratory that applying rare-earth element as a fluorescent tracer to measure the nutritive relationship in food chain quantitatively. By adopting fluorescent labeling method, the thesis focused on studying the food intake capacity of Ummelita insecticeps (Bosenberg et Strand), which is the dominant species of spider population in paddy field, influenced by various factors such as own weight, ratio of spiders to plant hoppers, pesticide and herbicides. Meanwhile, starvation endurance of Ummelita insecticeps under the circumstances of various temperatures was measured, too. The thesis aims to provide accurate parameters for integrated pest management (IPM) in paddy field and the theoretical basis of protecting Ummelita insecticeps in the situation of lack of prey like the period after applying pesticide, during harvesting season and at the winter.1. Content of fluorescence in the Sogatella furcifera adultsIn the booting stage of rice plant, the Sogatella furcifera adult samples averagely weighed 0.386 mg. per individual in terms of dry body mass. Measuring the amount of fluorescence in the Sogatella furcifera adults who had lived on the fluorescence labeled rice plant 3 days, each individual absorbed fluorescence 0.006 u g from the rice plant totally. Converted into biomass unit, each gram dry biomass of Sogatella furcifera contained 16.128 ug in 3 days, that means, 5.376 ug for every day.The Sogatella furcifera adults who lived in milking stage of rice plant were a little bigger than those lived in booting stage. They weighed 0.617 mg. per individual in average. Each Sogatella furcifera adult absorbedfluorescence 0.009 u g from the rice plant in 3 days (more than 0.006 u g /ind. in booting stage of rice plant). Based on dry biomass unit, each gram dry biomass contained fluorescence 14.912 u g totally in 3 days and 4.971 u g for 24 hours (less than 5.376 u g /g/d in booting stage of rice plant).2. Food intake capacity of Ummeleta insecticeps in relation to its weightThe tested spiders' weight varied from 0.2 mg. to 1.6mg.. All of them were fed with the fluorescence labeled white-backed planthoppers in 24 hours (spider : planthopper = 1 - 15). The result showed that the tested spiders averagely weighed 0.77mg. (dry). The mean amount of fluorescence content in each spider was 0.014ug . The individual number of predated planthoppers by a spider in 24 hours was 2.370 according to the fluorescence content of the planthopper individual in rice booting stage. In 24 hours, each gram of dry spider contained fluorescence 18.465 14 g , which needed to take in 1.691 gram of plant hoppers according to the fluorescence content of each gram planthopper in rice booting stage.Data analysis indicated that the amount of food intake per Ummelita insecticeps individual was positively correlated with its weight. The relationship could be fitted by the linear equation y = 0.6571x + 1.8497. But the regression coefficients between the amounts of food intake per gram dry body mass of the spider and its weight was negative. It was fitted as following linear equation y = -1.7768x + 3.0596. Therefore, the bigger the Ummelita insecticeps individual was, the more it ate, but the less each gram of it ate.3. Influences of different spiders' density and planthoppers' density on food intake capacity of Ummelita insecticepsIn the space of 330cm3, the amount of food intake per Ummelitasituation of applying pesticide repeatedlyWithin 13 days after spraying the pesticide liquid, the tested spiders all ate the least in the 2nd day regardless the concentrations of the pesticide. Then they ate a little more and more as the time going. The spiders' food intake capacity was weakest at the first time of the spraying the pesticide. In the second and the third time of spraying the pesticide, they can predate a little more. High concentration of the pesticide did more harm to the tested spiders. They needed more time to recover their predatory capacity. The amou...