Potential of five non-spore-forming bacteria, originated from the European cockchafer, Melolontha melolontha (Linnaeus, 1758) (Coleoptera: Scarabaeidae), on three economic insect pests

Abstract

Five non-spore-forming bacteria were isolated from the European cockchafer, Melolontha melolontha (, ) (Coleoptera: Scarabaeidae). Their potential was tested against the three economic insect pests, the great spruce bark beetle, Dendroctonus micans Kugelann (Coleoptera: Curculionidae); the pine processionary, Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae); and the gypsy moth, Lymantria dispar (Linn.) (Lepidoptera: Erebidae), to find an effective biological control agent. All isolated bacteria were cultured and identified using VITEK bacterial identification systems and 16S rRNA gene sequence analysis. The bacteria were identified as Enterobacter cloacae complex (isolate 1M), Serratia marcescens (isolate 3M), Pseudomonas aeruginosa (isolate 4M), Kocuria kristinae (isolate 5M), and Serratia liquefaciens (isolate 8M). Laboratory experiments, carried out to evaluate the virulence of these isolates, showed that all isolated bacteria had a pathogenic effect on the tested pests. E. cloacae had 35, 56.7, and 84%; S. marcescens 50, 60.9, and 47.8%; P. aeruginosa 55, 69.6, and 48%; K. kristinae 40, 43.5, and 16%; and S. liquefaciens 45, 65.2, and 36% mortality rates on the larvae of D. micans, T. pityocampa, and L. dispar, respectively. The isolated bacteria can be considered in integrated pest control programs.