5种药剂对不同发育阶段白蜡绵粉蚧Phenacoccus fraxinus的室内毒力

Indoor toxicity of five pesticides against different developmental stages of Phenacoccus fraxinus

白蜡绵粉蚧Phenacoccus fraxinus Tang是白蜡Fraxinus chinensis Roxb.的一种重要害虫。为筛选出高效防治白蜡绵粉蚧的药剂,本试验采用浸渍法测定了5种药剂对不同龄期白蜡绵粉蚧的毒力。测试的5种药剂对白蜡绵粉蚧1龄若虫致死中浓度为18.48~24.52 mg/L,均表现较高的毒力。对2龄若虫和成虫的致死中浓度分别为18.48~76.25 mg/L和44.00~79.53 mg/L,毒力稍低于1龄若虫。但5种药剂对白蜡绵粉蚧3龄若虫的毒力明显低于其他龄期,除20%丁硫克百威乳油毒力较高(42.00 mg/L)外,其余4种药剂的致死中浓度为97.73~132.24 mg/L。因此,5种药剂对白蜡绵粉蚧1、2龄若虫和成虫毒力较强且稳定,均可作为防治白蜡绵粉蚧低龄若虫和成虫的优良药剂,但3龄若虫最好选用毒力较高的20%丁硫克百威乳油进行防治。

Phenacoccus fraxinus Tang is an important sucking pest of Flaxinus chinensis Roxb.In order to screen high-efficacy pesticides for control of P.fraxinus,the toxicities of five pesticides against different stages of P.fraxinus were determined by dipping method.The results showed that all the five pesticides had high toxicity to the 1st instar nymphs of P.fraxinus,with median lethal concentrations(LC_(50))of 18.48-24.52 mg/L.The five pesticides also exhibited relatively high toxicity to 2nd instar nymphs(LC_(50) values ranged from 18.48 to 76.25 mg/L)and adults(LC_(50) values ranged from 44.00 to 79.53 mg/L),but slightly lower than those to the 1st instar nymphs.However,the toxicities of the five pesticides to the 3rd instar nymphs were significantly lower than those to other stages except for carbosulfan 20% EC(LC 5042.00 mg/L),the LC 50 values of other four pesticides were 97.73-132.44 mg/L.Therefore,the five pesticides can be used to control the 1st-2nd instar nymphs and adults of P.fraxinus,while carbosulfan 20% EC can be used to control the 3rd instar nymphs of P.fraxinus.