Effect of the entomopathogenic fungus, beauveria bassiana, combined with diatomaceous earth on the red flour beetle, tribolium castaneum (Herbst) (tenebrionidae: Coleoptera)

Abstract

An assay was designed to evaluate the efficacy of each entomopathogenic fungus, Beauveria bassiana, and diatomaceous (DE) and their combinations at concentrations of 1 × 106 and 1 × 108 conidia kg−1 of wheat and 200 and 400 ppm, respectively, on the red flour beetle, Tribolium castaneum (Herbst) (Tenebrionidae: Coleoptera), infesting wheat. Percent mortality of T. castaneum was recorded after 7, 14, and 21 days. Percent mycosis on dead cadavers was assessed after 21 days. Alive adults were removed from plastic jars after 21 days and kept for the next 60 days to assess the progeny production. The results indicated that the highest concentrations of B. bassiana and DE in their combinations were more effective for the virulence and progeny suppression of T. castaneum. Maximum mean percent mortality (88.13%) was recorded by B. bassiana (1 × 108 conidia kg−1 of wheat) and DE (400 ppm) in their combination after a 21-day exposure interval, while a minimum percent mean mortality (10.00%) was recorded by B. bassiana (1 × 106 conidia kg−1 of wheat) alone. The maximum percent mycosis (78.89%) on dead cadavers was recorded at a low concentration rate (1 × 106 conidia/kg) of B. bassiana. Mean progeny adult emergence was the highest (62.67 adults) at the low concentration of B. bassiana alone. Present studies showed that B. bassiana and DE are more effective in combination against T. castaneum on wheat as both substances are advantageous.