Effect of Beauveria bassiana Wettable Powder against Leptinotarsa decemlineata (Say)

The strain 1513 isolated from infected Leptinotarsa decemlineata was purified and identified to be Beauveria bassiana and conserved in agricultural culture collection of china(ACCC) with the number of ACCC32222.To evaluate its biocontrol potential,virulence of the isolate against different instar larvae of L.decemlineata was investigated under different spore concentrations.Results showed that when the temperature was 22 28 ℃,the cadaver rate of 1st 2nd instar larvae increased with the increase of spore concentration.The LC50 values of 9 days after treatment on 1st 2nd instar larvae and 8 days after treatment on 3rd 4th instar larvae of L.decemlineata were 3.09×107 conidia mL 1 and 9.92×107 conidia mL 1,respectively.Eggs of L.decemlineata were not inhibited when the spore concentration was 1×107 conidia mL 1.Field trials in Xinyuan of Xinjiang demonstrated that the mortality of L.decemlineata reached 98.87% when treated with B.bassiana wettable powder at about 2250 g ha 1 after 18 days,and cadaver rate on the earth surface was 53.91%.However,cadaver was only found in the soil with cadaver rate of 19.61% in Nileke of Xinjiang.