Efficacy of isolates of an entomopathogenic fungus on coffee berry borer

The coffee berry borer (Hypothenemus hampei F.; Coleoptera: Scolytidae) is an important pest of coffee in sub-Saharan Africa (SSA), which causes enormous damage to the crop and yet is difficult to control. The objective of this study was to evaluate the efficacy of Beauveria bassiana, an entomopathogenic fungi, on H. hampei F. pest under laboratory conditions. Isolates of B. bassiana were isolated using the suspension-dilution method on Beauveria Selective Medium (MSB), from Daloa (Cote d’Ivoire) soil sample. Five isolates of B. bassiana, namely TE3.211, TE3.222, TE7.311, G.233 and G.232, were tested on coffee berry borer, through two inoculation methods (active and passive). The isolation results showed that 65.51% mortality rates caused by B. bassiana varied from 48.48 to 99.66%. Isolate TE7.311 caused a mortality rate of 96.66% for active inoculation of bark beetles and 70% for passive inoculation of cherries. Isolate TE3.211 by active inoculation of bark beetles and isolate G232 by active inoculation of cherries generated mortality rates of 98.33 and 99.66%, respectively. The pathogenicity tests carried out on the bark beetle presented LT50s, which varied from day 2 to day 9 for the passive method. In contrast, as for the active method, TL50 were observed from day 1 to day 2. The results of this study confirm the efficacy of B. bassiana as biological control agents against coffee berry borer.