Virulence of bacteria associated with the formosan subterranean termite (Isoptera: Rhinotermitidae) in New Orleans, LA

Abstract

Examination of Formosan subterranean termites, Coptotermes formosanus Shiraki, for possible biological control agents revealed the presence of 15 bacteria and one fungus associated with dead termites from New Orleans, LA, USA. All but one of the bacteria species were gram-negative bacteria. Bacterial isolates from dead termites were primarily Serratia marcescens Bizio that caused septicemia in C. formosanus and also appeared to contain proteolytic enzymes. Multiple strains of S. marcescens were isolated. Six of the eight strains of S. marcescens were red, probably not pathogenic in humans, and candidates as biological control agents for C. formosanus. Bacteria isolated from termite substrata included Corynebacterium urealyticum Pitcher, Acinetobacter calcoacet/ baumannii/ Gen2 (Beijerinck), S. marcescens, and Enterobacter gergoviae Brenner. Some of these bacteria are potential human pathogens. Forced exposure bioassays demonstrated that the T8 strain of S. marcescens killed 100% of C. formosanus by day 19.