Efficacy of native isolates of Metarhizium spp. in the control of the weevil (Metamasius hemipterus) of sugarcane in laboratory conditions

Abstract

The objective of this work was to evaluate the efficacy of four native isolates of Metarhizium spp., in the control of adults of Metamasius hemipterus in laboratory conditions. A completely randomized design with seven treatments and five repetitions was used. The treatments were the four native isolates (TI6301, TS6304, PS5002, PS5003; at a concentration of 1 x108 conidia.mL-1), Chemical (Engeo at a dose of 1mL.L-1 water), a commercial biological (Micosplag at a dose of 0.5 g.L-1 of water) and a control treatment with sterile distilled water. The treatments were applied by immersion. Mortality assessment was recorded at 5, 10, and 15 days after treatment application. Abbott's formula was used for the correction of mortality. To determine the confirmed mortality, dead adults were conditioned in humid chambers to verify the presence of mycelium on dead insects. The data was processed by ANOVA, the comparison of means was made with the Tukey test (P <0.05). The chemical treatment showed an immediate response in adults of M. hemipterus with a 100% mortality efficiency before the first 24 hours, while the native isolates began to reflect mortalities from the second day. The native isolates of Metarhizium spp. TI6301, TS6304 and PS5002 caused accumulated and corrected mortalities above 70%, and Micosplag treatment reached an efficiency of 4.17%. Confirmed mortalities were between 72.4 and 76% with native isolates TS6304 and TI6301, respectively on adults of M. hemipterus.