Entomopathogenic fungi in the control of Hedypathes betulinus and evaluation of persistence

Abstract

Hedypathes betulinus (KLUG, 1825) (Coleoptera: Cerambycidae) is the main pest of “erva-mate” (Ilex paraguariensis) culture. Focusing its control, it was evaluated in laboratory and field the entomopathogenic fungi using. In laboratory, it was evaluated the infectiveness of the strains of the following fungi: Beauveria bassiana (Bals.)  Vuillemin, B. brongniartii (Sacc.) Petch, Metarhizium anisopliae (Metsch.), Sorokin and Paecilomyces (= Isaria) sp. Bainier, in adults specimen of H. betulinus. The insects were immersed in a conidial suspension at a concentration of 10⁷ conidia mL^-1. After the application the insects had been kept at laboratory for mortality register. It was verified that B. bassiana (CG 716) was more infective, reaching to 100% of mortality. It estimated LC₅₀ of isolated CG 716 of B. bassiana with five concentrations and a variation of l0⁵ to l0⁹ conidia mL^-1, along the control plot. The estimated LC₅₀ was 2,0 x 10⁶ conidia mL^-1, ranging from 6 x 10⁵ to 5 x 10⁶ conidia mL^-1. The persistence of strain CG 716 of B. bassiana - formulate oil was evaluated in field, producing the highest mortality, at the first three weeks after the application of the fungus, with a variance of 95 to 78 %, with a decreasing of 65 to 47% , along one and two months after the application , respectively.