Pathogenicity of Beauveria bassiana against Chnootriba similis Thunberg (Coleoptera: Coccinellidae) under laboratory and screen house conditions

The herbivorous ladybird beetle, tef epilachna Chnootriba similis Thunberg (Coleoptera Coccinellidae), is a serious pest of cereal crops in many African countries. In Ethiopia, it was reported as a pest of tef (Eragrostis tef (Zuccagni) Trotter (Poaceae) and caused severe damage to all cereal crops in the country. This study was designed to investigate the pathogenicity of different Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) isolates (1x108 conidia mL-1 concentration) against egg, larvae and adults of C. similis under laboratory and screen house conditions. All isolates of B. bassiana showed pathogenicity in all life stages of C. similis. Among the tested isolates, PPRC-56 caused the highest mortality in eggs (76%), first instar larvae (36%), fourth instar larvae (57%) and adults (78%) of C. similis, 11, 6, 8 and 16-days post treatments, respectively. The first and fourth instar larvae were more susceptible than the eggs and adults of C. similis. Our study showed that all B. bassiana isolates were highly effective at killing all stages of C. similis in both laboratory and screen house conditions. The study suggests using the entomopathogenic fungus B. bassiana as a biocontrol agent to control C. similis is very impressive.