Abstract

This research was carried out to evaluate the suppressive efficacy of entomopathogenic fungi Beauveria bassiana against adults of Callosobruchus maculatus (F.) and Sitophilusgranarius (L.) on stored grains in darkness (27±2°C and 65±5% RH). The insects were inoculated by following immersion in five aqueous suspensions with concentrations determined with preliminary tests and compared with untreated wheat and cowpea as control. Probit analysis showed that the lowest LT_{50 values in suspensions with highest concentrations (2.3 × 10^{7 conidia ml-1) were 6.63 and 10.45 days for C. maculatus and S. granarius, respectively. On the other hand, the LC50 values on day 9 post-treatment were 3.17 × 106 and 6.08 × 107 con.ml-1 for C. maculatus and S. granarius, respectively. Comparison of Lc50, LT50 values and mortalities indicated that in both assays, B. bassiana was consistently more virulent for C. maculatus than S. granarius. The overall results showed that these two pests were controlled successfully with entomopathogenic fungi Beauveria bassiana.}}

Key words: Callosobruchus maculatus, Beauveria bassiana, Sitophilus granarius, stored grain.