IMPACT OF BEAUVERIA BASSIANA ON THE COTTONWOOD BORER, PLECTRODERA SCALATOR (COLEOPTERA: CERAMBYCIDAE), IN A COMMERCIAL COTTONWOOD NURSERY.

Abstract

A commercial Beauveria bassiana (Balsamo) Vuillemin conidial formulation, AGB 6178, was applied as a soil drench against the cottonwood borer, Plectrodera scalator (F.), in a commercial eastern cottonwood, Populus deltoides, nursery. Doses of 0, 2 × 109, 2 × 1010 and 1 × 1011 conidia/m2 were applied in June 1986. The adult population was monitored throughout its flight period (June–August) for B. bassiana infection. Greater than 60% of the adults collected in the treatment area post-treatment were infected with B. bassiana. The impact of the fungal application on the larval population was assessed 8 months later by the removal and dissection of the treated rootstocks. Though no differences were detected in the number of second-year larvae recovered, the mean number of first-year larvae found at the high dose (1 × 1011 CFU's/m2) was significantly less (LSD, alpha 0.05) than the mean number of larvae found in the control treatment (0 CFU's/m2), 5.0 and 9.4 larvae/10 rootstocks, respectively.