Bioassay of contact insecticides to red imported fire ant,Solenopsis invicta Buren

Toxicity of 9 contact insecticides and media lethal concentration(LC_(50)) of 8 insecticides was bioassayed in the laboratory.Among them,both of knockdown rates and mortality of fire ant workers by 48% chlorpyrifos EC were as highest as 100% half an hour after treatment and knockdown rate of carbamate insecticides for ant workers reached as high 100% 8 hour after treatment.Although knockdown speed of fipronil and chlorfenapyr was slow,their mortality after 24 hour reached 100%.Beta-cypermethrin EC knocked workers down faster than others,but unfortunately the insects recovered soon.Bioassay indicated 98% cartap,one of nereistoxin insecticide,exhibited best toxicity to fire ant,beta-cypermethrin better,and DDVP and carbosulfan worst.5% Fipronil EC,10% chlorfenapyr EC,48% chlorpyrifos EC,and 98% cartap and so on were recommended to be used as mound drench insecticides for fire ant control in grassy fields.