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一、水稻螟虫测报工作的改进(一)以幼虫发育进度推算螟蛾发生期。过去预测螟虫发生期是用化蛹率来准算,推算时间短,在5一10天之间;工作量大,预测一代要剥查6—9次。从1963年起我们加用老龄幼虫发育进度来推算,推算时间长,可达15—25天;剥查次数少,减为2—3次;几年来的实践证明,这种预测的准确性也较大。调查推算方法如下:调查方法与化蛹率调查方法相同,但剥查时必须将获得的活幼虫分龄填入表内。推算方法:三化螟幼虫一般有5龄,在温度27—29℃下,第一龄幼虫需4天,第二龄幼虫需4天,第三龄幼虫需5天,第四龄幼虫需6天,第五龄幼虫需7天,预蛹1—2天,蛹9天。例如五月十日在田间进行发育进度剥查,在剥到的总活虫数中,二龄幼虫占5%,三
First, the improvement of rice stem borer report (A) to the development of larvae to estimate the occurrence of Pyralidae. In the past, the occurrence of stem borers was estimated based on the rate of pupation, and the calculation time was short, ranging from 5 to 10 days. The work load was large, and it was predicted that the generation of pests would be checked 6-9 times. From 1963 onwards, we add the use of the development of old larvae to calculate the progress of a long time, up to 15-25 days; stripping fewer times, reduced to 2-3 times; years of practice has proved that the accuracy of this prediction is also Larger. The investigation and estimation methods are as follows: The investigation method is the same as the investigation of the pupation rate, but the live larvae obtained must be entered into the table at the time of stripping. Calculation method: Larvae of the three borer larvae generally have 5 years, at the temperature of 27-29 ° C, the first instar larvae need 4 days, second instar larvae need 4 days, the third instar larvae need 5 days, the fourth instar larvae need 6 Day, 5th instar larvae take 7 days, pre-pupa 1-2 days, pupa 9 days. For example, in the field on May 10, the progress of development was stripped. Among the total number of live insects stripped, the second instar larvae accounted for 5%