Effect of isolates of Beauveria bassiana pathogenic to leafhopper cacao Horiola picta (Hemiptera: Mambracidae)

Abstract

The leafhopper Horiola picta (Membracidae: Smiliinae: Trogopini) is a cocoa secondary pest of Transamazônica and Xingu region, and microbial control is an alternative to keep these populations below the economic injury level. This study aimed to evaluate the virulence of isolates GC 157 and GC 165 of Beauveria bassiana under different conidia concentrations in insect adulthood. The following concentrations were used: 1x10 4 , 1x10 5 , 1x10 6 , 1x10 7 ,1x10 8 conidia ml -1 and the control to inoculate the insects were fed with cocoa shoots and young fruit, exchanged daily. For the effect of B. bassiana on H. picta adults performance differences were observed between the concentrations 10 4 a 10 8 conidia ml -1 , around 70.31 to 90.31% of total mortality respectively to isolated CG 157, and the isolated CG 165 was obtained 62,50% from the concentration 10 4 conidia mL -1 , reaching 82% mortality with a concentration of 10 8 conidia mL -1 . However, both the isolated CG 157 as CG 165, show good infective capacity. Confirmed mortality ranges from 27,2% a 72,2% both for isolated as CG157 to CG165 and showed positive linear correlation (R ² = 0.97) and (R² = 0.98) respectively. The lethal time (LT 50 ) for CG157 and CG165 isolated according to Lethal Concentration (LC50) of 10 4 conidia-1 was 1.075 days for the isolated CG157 and 2.30 days for the CG 165 isolated.