NOTE ON EFFECTS OF FEEDING GRASSHOPPERS TWO PATHOGENIC SPECIES OF BACTERIA SIMULTANEOUSLY

Abstract

Grasshoppers fed a combination of 2 pathogens generally die from an infection produced by one organism only. The organism taking precedence was generally that fed in greater numbers. When Pseudo-monas aeruginosa (Schroeter) Migula and Serratia marcescens Bizio were fed in equal numbers, all deaths were caused by S. marcescens, but P. aeruginosa caused all deaths when it was fed in greater proportion. Crowding of the grasshoppers and its attendant possibilities of cross-contamination and cannibalism appeared to have more influence on lowering the LD50 than did the combination of pathogens or the ratio in which they were fed. It was concluded that, under the conditions of testing and in the combinations tested, no great advantage is obtained by feeding grasshoppers a combination of 2 pathogens.