Basic Ecology for Integrated Management of the Silverleaf whitefly ( Bemisia argentifolii ) on Cantaloupe in a Net-house
Date Issued
2006
Date
2006
Author(s)
Lin, Feng-Chyi
DOI
zh-TW
Abstract
The objective of this study is to develop the integrated techniques for the management of the silverleaf whitefly, Bemisia argentifolii (Bellows and Perring), on cantaloupe (or muskmelon) cultivated in the net house. Developmental time and mortality of B. argentifolii were determined at ten constant temperatures ranging from 16 to 34℃ on cantaloupe. The least cumulated immature mortality of B. argentifolii from egg to adult was 6% at 26℃ and 28℃. Developmental time from egg to adult at 16-28℃ ranged from 15.4 to 55.3 days on cantaloupe. The developmental rate (D) could be raised by increasing temperature (T) as shown in the linear regression equation: D = -0.044321+ 0.003849T (r2= 0.992, p<0.01). However, 15.8 to 21.1 days were needed when temperature was around 30 to 34℃, the higher the temperature the lower the developmental rate. The low developmental threshold temperature and degree-day (DD) requirements from egg to adult were 11.5℃ and 259.807 DD, respectively. A nonlinear temperature- dependent model (Lactin-2) fitted well to the data for 16 to 34℃. Accordingly, the lethal upper temperature was estimated as 37.635 ± 1.0126℃, and the optimal temperature and developmental temperature threshold of B. argentifolii from egg to adult were 29.9℃ and 9.1℃, respectively.
The mean longevity of female and male was 30.7 and 17.4 days, 27.1 and 21.7 days, 28.1 and 24.5 days, 34.2 and 27.6 days, 19.5 and 12.8 days respectively at 16, 20, 24, 28 and 32℃. Fecundity was 80.7, 160.4, 196.1, 337.5 and 26.1 eggs per female on cantaloupe respectively at 16, 20, 24, 28 and 32℃. At 28℃ it had the highest net reproductive rate (Ro) (155.95), and the least at 32℃ (11.24).The shortest mean generation time was 26.28 and 26.18 days respectively at 28 and 32℃, but the maximal one was 72.02 days at 16℃. The intrinsic rate of increase (rm) and finite rate of increase (λ) was 0.1925 and 1.212 at 28℃. The longest doubling time was 15.06 days at 16℃, but the shortest was 3.6 days at 28℃.
I conducted random sampling eight times in a net house to examine spatial pattern and to estimate optimal sample size of B. argentifolii adults on cantaloupe plants. The vertical distribution of the whiteflies on cantaloupe plant was studied by inspecting adults with leaf turn method. More than 80% adults occurred on the 3rd-9th leaves top down from terminal bud of cantaloupe plant, and these grouping leaves were considered as a suitable sampling unit. Iwao’s mean crowding (m) – mean (m) regression and Taylor’s power law were used to analyze the data. Parameters derived from Taylor’s power law were a=3.917 and b=1.538 (r2 =0.98), those from Iwao’s m-m regression were α=12.29 and β=1.327 (r2 =0.97). Both Taylor’s b and Iwao’s β were significantly greater than 1, indicating that the whiteflies spatial pattern was an aggregative type. Using these parameters, I estimated the optimal sample size necessary to achieve a predetermined statistical precision. At the 0.2 precision level, estimates of optimal sample size based on the Iwao’ patchiness regression and Taylor power law are less than 75 and 47, respectively, when the density exceeds 5 adult whiteflies per leaf. The density of the whitefly ranged from 7 to 137 adults per leaf during this survey. Therefore, in order to simplify the sampling method, I suggest that 10 random plants be taken to count the adult whiteflies on the 3rd to the 9th leaves under the terminal bud by turning the leaf to monitor the whitefly population in net house for pest control purposes.
Yield loss assessment indicated that the weight of the melon fruit was affected more by the climatic factors than the injuries caused by B. argentifolii. The yield loss of cantaloupe fruit by B. argentifolii was mainly resulted from the sooty mold disease on both leaves and fruits induced by the honey dew excreted. The results revealed the relation between the yield of cantaloupe per are (kg/are) and the whitefly density (x, No. adults/leaf) can be expressed as a linear regression equation: y= 73.17-3.15x (r2= 0.8716, p<0.05). The yield decrease rate was at 3.15 kg/adult per are and the economic injury level (EIL) was estimated at 2.98adults/leaf on cantaloupe in net house when imidacloprid was used.
Subjects
銀葉粉蝨
洋香瓜
綜合防治
發育速率
族群介量
最適樣品數
產量損失
經濟危害水平
Bemisia argentifolii
cantaloupe
integrated management
developmental rate
population parameter
optimal sampling size
yield loss assessment
economic injury level (EIL)
Type
thesis
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