桑白盾蚧的研究

桑白盾蚧在陕西严重危害泡桐。年发生二代,以雌成虫越冬;每年5月上、中旬为若虫孵化盛期,是化学防治最有利的时机。发现日本方头甲和榆蛎蚧跳小蜂两种重要天敌,其中跳小蜂自然寄生率可达20.45％,对蚧虫起一定抑制作用。使用40％氧化乐果2倍液、4倍液涂干,防治雌成虫,杀虫率分别可达79.3％、74.5％;使用50％杀螟松800倍液、1000倍液喷雾,防治初孵若虫,杀虫率分别可达96.9％、93.3％。

Studies on Biology and Control of Pseudulacaspis pentagona (Targ.)

Pseudulacaspis pentagana (Targ. ) seriously damaged paulownia trees in Shaanxi province and now is tending to be enormous. It had two generations per year and overwintered by female adults. Its nymphs appered mostly in the early and middle May, which is the best time for chemical control. Cybocephalus nippanicus Endroby-yenge and Anabrolepis zetterstedtii (Westwood) were found the main natural enemies. The natural parasitic rate of Anabrolepis zetterstedtii Westwood was 20. 45%. With 2 and 4 times liquid of 40% omethoate to control female adults, the death rates were 79. 3% and 74. 4% respectively. Spraying with 800 and 1 000 times liquid of 50% fenitrothion to control the first instar nymphs, the death rates reached 96. 9% and 93. 3% respectively.