Isolation and identification of Pseudomonas entomophila from Pinus massoniana and its insecticidal activity against Monochamus alternatus

Abstract

ABSTRACT To identify microorganisms that can colonise pine trees and have a toxic effect on Monochamus alternatus (Coleoptera: Cerambycidae), we isolated the CSHH2 bacterial strain from the phloem of nematode-infected Pinus massoniana (Coniferales: Pinaceae). The isolated strain was identified as Pseudomonas entomophila (Pseudomonadales: Pseudomonadaceae) based on phenotypic traits, 16S rDNA gene sequencing, homology analysis, phylogenetic tree analysis, and physiological and biochemical analysis. P. entomophila CSHH2 was resistant only to cefathiamidine and polymyxin B but was sensitive to most drugs tested in the antimicrobial sensitivity assay. Furthermore, the bioassay indicated that the CSHH2 strain possesses significant insecticidal activity against the second instar larvae of M. alternatus (p < 0.0001). LC50 and LT50 were 5.37 × 107 CFU mL−1 and 5.630 days (1.63 × 108 CFU mL−1 bacteria per larva) respectively at 10 days post-treatment. The present study is the first to identify the toxicity of P. entomophila against M. alternatus larvae.