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分别采用浸渍法和药膜法测定了辛硫磷对枸杞木虱不同发育期若虫和成虫的毒力,同时测定了辛硫磷对不同龄期枸杞木虱羧酸酯酶(Car E)活性的抑制作用及酶的动力学常数。结果表明:辛硫磷对枸杞木虱的LC_(50)值随若虫龄期的增大而升高,至成虫期再相对降低,其对5龄若虫的LC_(50)值为0.995 mg/L,是对1龄若虫LC_(50)值(0.047 mg/L)的21.2倍。辛硫磷对不同龄期枸杞木虱羧酸酯酶活性的抑制作用I50值及酶的Km和Vmax值也均随着试虫龄期的增大而升高,至成虫期则I50值稍有降低。研究表明,辛硫磷对枸杞木虱的毒力与对其羧酸酯酶活性的抑制作用间存在密切关系,利用辛硫磷防治枸杞木虱时,以选择龄期较低时用药为宜。
The toxicities of phoxim to nymphs and adults at different developmental stages of Lycium barbarum were determined by impregnation and membrane assay respectively. The effects of phoxim on CarE activities in different stages of Lycium barbarum were also studied Inhibition and enzyme kinetic constants. The results showed that the LC 50 value of phoxim to P. medinalis increased with the increase of the age of nymphs, and then decreased to a relatively low level during the adult stage. The LC 50 value of 5th instar nymphs was 0.995 mg / L , Which was 21.2 times of LC 50 value of first instar nymph (0.047 mg / L). Phoxim inhibited the carboxylesterase activity at different stages of P. medinalis I50 value and enzyme Km and Vmax values also increased with the age of the test insects increased to the adult stage I50 value slightly reduce. Studies have shown that there is a close relationship between the virulence of phoxim and the inhibition of its carboxylesterase activity. When phoxim is used to control the psyllids, it is advisable to choose the drug with the lower age of choice.