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1959—1960年作者等在江西、湖南等地区配合大面积防治森林害虫之际,开展了DDT等化学药剂对于不同越冬时期的马尾松毛虫幼虫的毒效试验。据野外观察结果,将马尾松毛虫越冬幼虫划分为5个时期。即越冬前活动期、越冬前期、越冬期、越冬后期、越冬后活动期。试验证明:不同化学药剂对越冬松毛虫幼虫的毒效随着不同时期和温度条件而变化。就一般论:DDT的效果,在比较低温(日均温10—20℃)时特别显著;666及敌百虫的效果,在比较高温时(20℃以上)为显著。其中尤以敌百虫为更甚。DDT对不同时期幼虫的毒效大小为:越冬后期>越冬前期>越冬期>越冬前活动期>越冬后活动期≥夏季(4-5龄)幼虫;其中以越冬后期幼虫抵抗力最弱。从原则上论这是施药的最适宜时期,从25％ DDT乳剂4,000倍稀释液在越冬后期(2,3月间)施用,毒效可达92％以上,用6,000倍稀释液亦达82％以上。如用γ6％可湿性666,800倍稀释液在越冬前、后期使用,毒效可达70-80％以上。50％敌百虫乳剂在温度20℃以上时(越冬前、后活动期)毒效显著增高。此时如用5,000-6,000倍稀释液喷洒,毒效可达70-80％左右。由此,作者认为:在长江以北,每年发生2代以下的松毛虫地区,可用DDT和666稀释液在越冬前、后期进行防治。长江以南,每年发生2代以上的马尾松毛虫地区,不但可用DDT、
From 1959 to 1960, when cooperating with a large area of forest pests in areas such as Jiangxi and Hunan, the authors conducted experiments on the toxic effects of DDT and other chemical agents on Dendrolimus punctatus larvae at different wintering periods. According to field observations, overwintering larvae of Masson’s pine caterpillars were divided into five periods. That pre-winter activities, pre-winter, winter, winter, post-winter activities. Tests show that: the toxic effects of different chemicals on the winter pine caterpillar larvae change with different periods and temperature conditions. In general terms: The effect of DDT is particularly pronounced at relatively low temperatures (average daily temperature 10-20 ° C); the effect of 666 and trichlorfon is significant at higher temperatures (above 20 ° C). Especially trichlorfon is even worse. The toxic effects of DDT on larvae at different stages were as follows: overwintering period> overwintering period> overwintering period> overwintering period> overwintering period> summer (4-5 instar) larvae; In principle, this is the most suitable time for application, with a 4,000-fold dilution from a 25% DDT emulsion applied during the late winter (February and March) with a toxic effect of over 92% and up to 82% with a 6,000-fold dilution %the above. Such as the use of γ6% wet 666,800 times dilution before and after the winter, the toxic effect of up to 70-80%. 50% trichlorfon emulsion at a temperature above 20 ℃ (overwintering before and after the activity period) significantly increased toxicity. At this time if 5,000-6,000 times dilution spray, the toxic effect of up to 70-80%. Therefore, the author thinks: In the area of pine caterpillars below 2 generations per year to the north of the Yangtze River, DDT and 666 dilutions can be used to control before and after wintering. South of the Yangtze River, occurring more than two generations of Masson pine caterpillar area, not only available DDT,