The first study on bacterial flora of pest beetles Sciaphobus squalidus, Tatianaerhynchites aequatus and Byctiscus betulae in the Republic of Moldova

Abstract

The present study was conducted to identify the microbial flora of pest weevils Sciaphobus squalidus (Gyll.), Tatianaerhynchites aequatus (L.) and Byctiscus betulae L., which may provide novel approaches for insect biocontrol. According to morphological, physiological, biochemical and molecular properties thirteen bacteria were revealed and characterized. Ten of these bacteria were identified at the species level and the rest at the genus level. Isolates were identified as Staphyloccocus haemolyticus (Ta5), Bacillus cereus (Ss1), Pseudomonas moraviensis (Ss4), Pseudomonas fluorescens (Ss2), Pantoea agglomerans (Ss3, Bb3), Klebsiella pneumoniae (Ta1, Ta3, and Ta4), Erwinia billingiae (Ta2) and Erwinia spp. (Bb1, Bb2, Bb4). This is the first record of bacterial isolates (Ss4, Ta2 and Ta5) from any insect. The pathogenicity of bacteria was tested against adults of S. squalidus, T. aequatus and B. betulae and three of them showed insecticidal activity. The highest activity, 93% had B. cereus on S. squalidus and 90% on B. betulae within five days. The maximum activities of other two isolates Ss2 and Ss4 were determined as 73% and 46% against S. squalidus. Our data can offer useful information for future investigations on bacterial agent development and implementation as insecticides in agricultural system. © 2014 Versita Warsaw and Springer-Verlag Wien.