Selectivity Of Bemisia Tabacib-biotype To Different Tobacco And Toxicity Determination Of Insecticide

Since Bemisia tabaci (Gennadius) B-biotype invaded into China, it has caused a serious ecomomic loss in agriculture, and has threatened the tobacco planting in Fujian province. In order to know the preference of B. tabaci to main tobacco cultivated varieties of Fujian, and the toxicities of insecticides to whiteflies, six tobacco varieties(cv.s CB-1, K326, Minyan7, Yunyan87, Yunyan85and Honghuadajinyuan) were chosen in the study, the perching, oviposition, feeding behaviors, growth and development of whiteflies on different tobacco varieties were observed, as well as toxicities of five insecticides (matrine, abamectin, cypermethrin, methomyl and imidacloprid) to different development stages of whiteflies were determined.(1) The effects of varieties and temperatures on the perching and oviposition of whiteflies were observed. The test results of interference and not interference showed that the perching and oviposition of whiteflies were significant affected by tobacco varieties and temperature (18℃,22℃,26℃,30℃,34℃). At different temperatures, the numbers of adult and fecundity were more on Honghuadajinyuan than those on other varieties, and they were less on Yunyan87and Yunyan85.(2) The development period, survival rate, longevity and fecundity of female adults on different varieties were observed. The results showed that these biological characters of whiteflies indicated significant differences on different varieties. The development period of whiteflies was the shortest on CB-1and the longes on Minyan7; the survival rate was the highest on Honghuadajinyuan and the lowest on Minyan7; both the longevities and fecundities of female adults were lower on Minyan7and higher on K326.(3) The feeding behaviors of female adults on six tobacco varieties were observed by electrical penetration graph (EPG) technique. There were significant differences in the ratio of non-probing waveform, total duration of salivation into sieve elements (waveform E1), the total duration of phloem ingestion (waveform E2) of female adults on different varieties. Female adults preferred Honghuadajinyuan to Minyan7and Yunyan87.(4) The toxieities of five insecticides to different development stages of whiteflies were determined with leaf-dipping method. The results showed the toxicities of abamectin and matrine were stronger to all development stages; the toxicity of imidacloprid was moderate to nymphs, but weak to eggs and adults; the toxicities of methomyl and cypermethrin were weak to any development stages.In conclusion, the effects of tobacco varieties were significant on perching, oviposition, feeding behaviors, development and fecundity of B. tabaci B-biotype. Their perching and oviposition were also affected by temperatures. B. tabaci B-biotype preferred Honghuadajinyuan to Yunyan87and Minyan7. The toxicities of Abamectin and matrine were stronger to all development stages. Therefore, B. tabaci B-biotype could be controlled effectively in the fields with planting insect-resistant tobacco and using insecticides reasonably.