Screening of Beauveria bassiana (Hyphomycetes) isolates against Choristoneura rosaceana (Lepidoptera: Tortricidae)

Abstract

AbstractTwenty-three isolates of Beauveria bassiana (Balsamo) Vuillemin from different hosts and geographical origins were evaluated under laboratory conditions for various aspects of virulence against 2- to 3-d-old third instars of the obliquebanded leafroller, Choristoneura rosaceana (Harris), a pest of apple, Malus domestica Borkhausen (Rosaceae), and several other orchard crops in North America. When submerged in a solution containing 107 conidia/mL, all B. bassiana isolates caused more than 66% larval and pupal mortality 60 d following treatment. Isolates 14, 16, 1525, 2727, and 2990 caused the highest (80–89%) larval and pupal mortality against C. rosaceana. Relative to the control, isolate 63 significantly increased and isolate 44860 significantly decreased larval development time. Isolates 37, 2727, and 2990 significantly decreased C. rosaceana pupal weight. Isolates 139, 2727, and 2990 significantly decreased the number of emerging females. In view of their larvicidal effects, as well as their carry-over effects on pupae and adult females, isolates 2727 and 2990 showed the best mycoinsecticidal potential against C. rosaceana.