BIOCONTROL SCIENCE AND TECHNOLOGY, vol.20, no.9, pp.973-982, 2010 (SCI-Expanded)
The leafroller weevil beetle (Rhynchites bacchus L., Coleoptera: Rhynchitidae) is one of the most serious pests of apple, plum, apricot, cherry and peach (nectarine) fruit worldwide. The aim of this study was to isolate and characterize pathogenic bacteria from this pest for possible use in biocontrol, and to determine their pathogenicity. R. bacchus were collected from the Eastern Black Sea Region of Turkey in 2007. Based on their morphological, physiological and biochemical features, five different bacterial isolates were obtained from adults and larvae. In addition, 16S rRNA gene was amplified and sequenced to confirm isolate identification. According to the numerical and molecular data, the culturable bacterial flora of R. bacchus was determined as Bacillus licheniformis (Rb1), Serratia marcescens (Rb2), Enterobacter hormaechei (Rb3), Paenibacillus sp. (Rb4), and Enterobacter sp. (Rb5). Isolate Rb2 produced the highest mortality (73%) against larvae within 10 days after inoculation (P < 0.05). The others, Rb1, Rb3, Rb4 and Rb5, caused 20, 13, 26 and 13% mortality in the larvae within the same period. These results indicate that S. marcescens Rb2 seems to be the most promising biocontrol agent against this pest.