ABSTRACT
Beauveria bassiana (Bals.) Vuill. (URM 3447) isolated from Castnia licus (Drury) and reisolated from eggs, larvae and adults of Anthonomus grandis (boll weevil), infected artificially was evaluated under various conditions (temperature: 27 ± 2º C, HR: 60 ± 10% and photophase: 14h). Estimation was made of the viability of B. bassiana (germination, colonial growth and conidiogenesis) in Potato-Dextrose-Agar (PDA) culture medium and virulence on the adult insect. Conidia in watery suspension with Tween 80 (0.05%), at various concentrations (0.62 x 106; 0.24 x 106 and 0.43 x 106 conidia/mL) constituted the inoculum for the viability and virulence tests. Determination was made of the rate of germination to reisolated and no-reisolated fungus, 18h after the inoculation. Growth of the colonies and conidiogenesis were estimated in the intervals of 3, 6, 9, 12 and 15 days. Suspension of the conidia in concentrations caused mortality of 96.7, 83.4 and 91.1% in LT50 of 5.4, 5.9 and 5.3 days, respectively. The relative pathogen potency (RPP) indicated that the fungus was more aggressive after reisolation. It was verified that B. bassiana (URM-3447), reisolated from eggs, larvae and adults of the A. grandis, presented high viability of germination, colonial growth and conidiogenesis in PDA medium and high degree of virulence on the adult insect, being able to be used as an insect control agent.
KEY WORDS
Beauveria bassiana
; biological control; viability;
Anthonomus grandis
; cotton