| The investigation of the dynamic change of the population of Bemisia tabaci and their distributions at different tobacco positions were investigated by five point sampling mode at Zhanshan town of Nanping city, Xinkou town of Sanming city and Longmen town of Longyan city from March to July in 2009. The amount of adults and larvae of B. tabaci at each town showed only one peak which occourred in May. Larvae occurred later than adults. The amount of the adults and larvae on the upper leaves were more than the middle and lower leaves of tobacco. The research of trapping B. tabaci with the yellow sticky trap (YST) showed that the amount trapped by three kinds of YSTs (20cm above canopy, equal to canopy and 20cm below canopy) were 79.33±22.55, 123.87±42.03 and 138.40±51.37 respectively. The amount of B. tabaci trapped by the two kinds of YSTs (equal to canopy and 20cm below canopy) were similar, without significantly different between them. But both of them were significantly different to the other one. The amount of B. tabaci trapped by YST being vertical to tobacco rows, YST being parallel to tobacco rows and YST being horizontal to tobacco rows were 105.07±39.39, 96.60±26.25 and 84.60±36.68 respectively without significantly different between them. The toxicity of imidacloprid, acetamiprid, fipronil to the adults of B. tabaci after 24 hours was determined by leaf-dip bioassay, spray bioassay, leaf-dip+spray bioassay. The LC50 of imidacloprid, acetamiprid and fipronil were 377.0383 mg/L, 360.4865 mg/L and 41.2435mg/L respectively by leaf-dip bioassay; 131.7235 mg/L, 128.1307 mg/L and 35.3137mg/L respectively by spray bioassay; 38.5034 mg/L, 33.5261 mg/L and 19.2805mg/L respectively by leaf-dip+spray bioassay. The LC50 of imidacloprid was similar to acetamiprid, but fipronil was the lowest. The LC50 of 3 pesticides determined by leaf-dip+spray bioassay were lower than the other methods.
|
PDF Full Text Request