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guang xi gui xian de ming hai gui lv ji qi yu ce fang fa de tan tao
Pages: 105-113
Year: Issue:  2
Journal: Acta Entomologica Sinica

Keyword:  世代发生型螟害预测方法播种期虫口密度加权平均幼虫密度预测预报多发型;
Abstract: The present paper attempts to find the rules of forecasting the possible degree ofdamage by the rice stem borer. According to the data from investigations in Kwangsiduring the years 1958--1964, it is generalized that the fluctuations of the damages causedby the borer can be divided, in conformity with its serial generations, into three differenttypes: the decreasing type, the increasing type, and the type with an increase in the thirdgeneration. The main cause resulting in the three different types is due to the different plantingdates. When the date is relatively early in the year, the decreasing type occurs; whenit is relatively late, the increasing type happens; when it is between these two dates, thetype with highest increase in the third generation takes place. A typical diagram has been made to illustrate the correlation between the differentplanting dates and the different types of borer damages. As soon as the date of plan-ting early rice is known, we can make use of the diagram to forecast the situation ofthe borer damage during the whole year. Having obtained the yearly average of the relative values of increase or decreasebetween the generations in each of the three developmental types, and the date of plan-ting of early rice in a given year, it is possible to calculate the degree of damage inthe succeeding generations. For short-term forecast of borer damage, larval density should be made the principalreference point. Computing from larval density and the degree of damage occurred, bymeans of the quadric curvilinear equation, estimates of damage will be obtained. The following equations have been used in the present research: Generation 1: 100y = 10.54e~(0.0019x) Generation 3: 100y = 16. 83e~(0.002x) Generation 2: 100y = 52.6 logx -- 100.5 Generation 4: 10y = 17.52 logx -- 41.98y indicates the percentage of the infestation of rice stem borer, x indicates the density oflarvae No./mow.
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