Efficacy of the fungus Beauveria bassiana (Balsamo) Vuillemin on the red palm weevil Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) larvae and adults under laboratory conditions

Abstract

The efficacy of a local isolate of the entomopathogenic fungus Beauveria bassiana was tested against the red palm weevil (RPW) Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) larvae and adults by direct spraying of the fungus conidiospores on the targeted stages under laboratory conditions. Larvae and adults were offered their natural food as tissue cuts from inside the same infested date palm trees from which they were collected. Six successive increased concentrations from 6 × 102 to 6 × 107 spores/ml were tested. Results revealed that the maximum mortality rates for the treated larvae of 3rd instar. Whatever the tested concentration was, the end mortality reached (100%). In case of the treated larvae of L7, the mortality rate ranged between 45 and 75% with the remaining individuals survived and formed cocoons in which they all died in the pupal stage. Also, all treated adult weevils died showing that the highest tested concentrations of B. bassiana killed the weevils in a shorter time (7 days) than in the tested lower concentrations (11 days). Meanwhile, mortality rates in the control for L3, L7, and adult weevils were always (0.0%)..