Toxicity and Control Effect of Different Insecticides on Rice Water Weevil in Leshan Rice Area,Sichuan Province
Using the overwintering Lissorhoptrus oryzophilus Kusehel adults as the object,the indoor toxicity of 17 insecticides on Lissorhoptrus oryzophilus Kusehel in rice fields of Leshan,Sichuan Province was measured.The control efficacy of the tested insecticides on Lissorhoptrus oryzophilus Kusehel was evaluated through field trials,and the effects of alternating application of different pesticides on field control efficacy were compared.The objective was to provide guidance for selecting control pesticides for Lissorhoptrus oryzophilus Kusehel,delaying pesticide resistance development and enhancing overall control efficiency.The results showed that biological insecticides such as 3％avermectin ME,25％spinetoram WG,1.5％pyrethrins EW,0.3％matrine AS,5 billion spores/g Beauveria bassiana SC,as well as chemical insecticides such as 40％chlorantraniliprole·thiamethoxam WG,200 g/L chlorantraniliprole SC,30％triazophos SC,35％dichlorvos·malathion EC and 22％malathion EC had higher toxicity to Lissorhoptrus oryzophilus Kusehel,with LC50 lower than 100 mg/L.The Lissorhoptrus oryzophilus Kusehel was more sensitive to changes in the concentration of chemical insecticides than that of biological insecticides.The insecticides of 40％chlorantraniliprole·thiamethoxam WG,200 g/L chlorantraniliprole SC,30％triazophos SC and 25％spinetoram WG had good rapid and sustained efficacy in controlling Lissorhoptrus oryzophilus Kusehel,with control efficacies ranging from 87.03％～92.29％after 7 days of treatment,and 70.93％～89.08％after 21 days of treatment.Different insecticides had varying degrees of effects on increasing the yield components of rice.The number of tillers,effective panicles and 1 000-grain weight of rice treated with the tested insecticides increased by 0.18％～10.06％,1.31％～14.57％and 3.21％～15.59％,respectively,compared to the water control,and the actual rice yield was significantly correlated with the field control efficacy of the insecticides.Furthermore,the alternating use of 25％spinetoram WG with 40％chlorantraniliprole·thiamethoxam WG,200 g/L chlorantraniliprole SC and 30％triazophos SC could improve the rapid and sustained control efficacy of insecticides to some extent.
Lissorhoptrus oryzophilus Kusehelinsecticidetoxicity testfield control efficacyrice yield
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