Spatial Distrubution and Sampling Method of the Silverleaf Whitefly (Bemisia argentifolii Bellows & Perring) on the Eggplant

• Main Authors: Chueh-Yu Pan, 潘珏瑜
• Other Authors: Chiou-Nan Chen
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/23716838142590007063

碩士 === 國立臺灣大學 === 昆蟲學研究所 === 88 === We conducted studies to examine the distribution patterns of the silverleaf whitefly （Bemisia argentifolii Bellows & Perring） on eggplant （Solanum melongena L.）in Tsau — tun, Nantou Hsien & Wufeng, Taichung Hsien from October to December, 1998 and May to July, 1999. Random leaf samples were taken weekly. The number of adults was counted on site, while eggs and nymphs on leaf samples were brought back to the laboratory and counted under the microscope. In terms of vertical distribution, adults were consistently more abundant on leaves at the top stratum of eggplants (90%) than on leaves at the middle and bottom. Eggs and nymphs were present more abundant on middle strata leaves. Using χ2-test to examine the fit of the negative binomial distribution and Poisson distribution to the frequency data collected from the field, we concluded that Poisson distribution pattern could not fit to any data set, but negative binomial distribution fitted some of them. Six out of 15 data sets of adults were in compliance with negative binomial distribution, so were three sets of eggs and seven sets of nymphs. Aggregation patterns measured by Taylor’s Power Law showed that adults were aggregative （b = 1.37）, eggs uniform （b = 0.88）, and nymphs random （b = 1.00）. Same conclusions were reached by the Iwao’s mean crowding（m*） and mean （m） regression （m* =α+βm）, with α= -0.26, β= 1.68 for adults and α= 2.83, β = 0.84 for eggs and α= 2.17, β= 1.01 for nymphs. The optimal sample size at different population densities as required by the precision levels at D = 0.1 and D = 0.2 was estimated according to the statistics derived above. For the extensional purposes a simple linear regression was established based upon the relationship between mean density and percentage of leaves infested.