Studies on the in vivo cellular reactions of insects: Fate of pathogenic and non-pathogenic bacteria in Galleria mellonella nodules

Abstract

The fate of radioactively-labelled bacteria within nodules of Galleria mellonella was examined over time and the percentage relative viabilities of a pathogen, B. cereus, and a non-pathogen, E. coli K12, were compared. Although large numbers of both species were killed within the nodules during the first six hours, B. cereus eventually overcame the insect's defence mechanisms and multiplied some 200-fold in the haemolymph, inducing a secondary bacteraemia and larval death. In contrast, E. coli remained entrapped in the cell aggregates and failed to kill their hosts. The nature and implication of an active killing mechanism within the nodules is discussed.