Characterization and virulence of Beauveria bassiana associated with auger beetle (Sinoxylon anale) infesting allspice (Pimenta dioica).

The incidence of auger beetle, Sinoxylon anale Lesne (Bostrichidae: Coleoptera), a destructive pest of cosmopolitan occurrence is reported for the first time on allspice trees, Pimenta dioica (L.) Merr. in Kerala, India. The insects bored through the basal region of fresh twigs resulting in dieback symptoms. Morphological characterization and sequencing of a partially amplified fragment of the mitochondrial CO1 gene (696bp) revealed the insect to be Sinoxylon anale. An entomopathogenic fungus was isolated from infected cadavers of S. anale that was identified as Beauveria bassiana (Bals.-Criv.) Vuill., sensu stricto (s.s.) (Ascomycota: Hypocreales) based on morphological and molecular studies. The partial sequences of the ITS, TUB, TEF and Bloc gene regions were sequenced. The fungus grew well in ambient room temperature conditions (28-32±2°C; 60-70% relative humidity) and the infection process on the insect was documented by scanning electron microscopy. Bioassay studies with the isolate indicated that the fungus was virulent against adult beetles as evidenced by the LC50 (3.6×10(6)conidia/ml) and ST50 values (6.8days at a dose of 1×10(7)conidia/ml and 5.8days at a dose of 1×10(8)conidia/ml, respectively). This is the first record of B. bassiana naturally infecting S. anale and the fungus holds promise to be developed as a mycoinsecticide.