【摘要】 本文研究在松树干上涂刷有持久性的药剂以防治越冬松毛虫的可能性。1947—48年在南京试验及实施防治的结果简述如下: (一)在实验室内使越冬松毛虫爬行越过涂有一市尺宽各种药液的松树干的结果,证明5％ DDT,1％γ666,与5％ 1068的悬液或溶液。在涂药的当天均 有相当高的杀虫效力,惟一周以后γ666与1068完全失效,仅DDT仍保持强大的毒力。DDT水悬液显著较DDT火油、大豆油或丙酮溶液为佳。涂有5％DDT悬液的松树杆曝露田间六星期后,杀死松毛虫能力仍达100％。 (二)据试验的结果,自制的可湿性DDT,内含DDT50％,稀释剂45％,与肥皂5％,尚适宜于防治松毛虫之用。 (三)松毛虫爬行的次数对涂药面积上DDT毒力的影响极微,在二十平方市寸涂有5％ DDT悬液的小面积上,9天之内经过1800头松毛虫爬行后,毒力仍未减小,死亡率尚在90％以上。 (四)夏季松毛虫较越冬松毛虫不易杀死。夏季松毛虫抵抗DDT的能力随龄期而增强。试验中显示如增加药液浓度至含DDT 10—15％,或增加涂药的宽度至2—3市尺,夏季幼虫亦能中毒死亡。故树干涂药法亦可应用在夏季防治上,惟必须在涂药后将松毛虫从树上击落,使其在爬返树冠时接触药剂而死亡。 (五)自然情形下,南京松毛虫在十一月即开始下树越冬,至来年三月初开始活动上树,故采用树干涂药法防治下?更多还原

【Abstract】 The pine caterpiller,Dendrolimus punctatus Walker, has the habit of leav-ing the crown part of a tree and hibernating under the loose bark of thetrunk. The present paper reports the successful control of this pest by treatinga part of the trunk with a DDT suspension. All experiments were carried outat Nanking, 1947-48. When solutions and water suspension containing 5% DDT, 1%γ 666,or 5% 1068 were applied with a brush to the trunk for a width of one footand over-wintering larvae were allowed to crawl over the treated area, all theinsecticides tested were found to be effective when freshly applied. After oneweek, how-ever, only preparations containing DDT remained effective. DDTwater suspension was markedly better than DDT in kerosene, soybean oil, oracetone. Trees treated with a 5% DDT water suspension were still very toxic tothe caterpillars at the end of six weeks. The number of caterpillars crawling over a DDT-treated area would notinfluence the toxicity of the DDT film under practical field conditions. In oneexperiment all area of twenty inches square, treated with a 5% DDT suspension,still showed high toxicity to the caterpillars after 1,800 larvae had crawled overthe area in a period of nine days. Caterpillars were found to be more resistant to DDT in summer than inwinter. By increasing either the concentration of DDT to 10-15% or thewidth of the treated area to 2-3 feet, the "trunk treatment method" could beused as well in summer, if the caterpillars were beaten down to the grounedafter the trees had been treated with DDT. Under the field conditions in Nanking, 1947-48, the pine caterpilIars beganto leave the crown part of the trees and seek hibenation quarters in November.They became active again early in March, hence tree should he treated withDDT not later than the dates mentioned above. A total of 157,658 trees were treated with DDT on the Purple Mountain,Nanking, 1948. Examinations showed that larval population decreased 90-99%in the treated area, while in the check area an increase in population of16-350% had been observed.更多还原