THE PASSAGE OF MICROORGANISMS THROUGH THE DIGESTIVE TRACT OF BLABERUS CRANIFER MOUNTED UNDER CONTROLLED CONDITIONS

Abstract

An improved technique for controlled feeding of insects is described. Mounted B. cranifer were kept alive for periods up to 145 days when fed a basic diet of skim milk, 0.5% sucrose, and 1% Difco yeast extract. Sterile molar sucrose alone maintained the insects for periods of at least 75 days. After determining the normal flora of droppings, specific organisms were fed in an attempt to implant the organisms in the digestive tract of the roaches. Salmonella typhimurium when fed in massive doses appeared to establish itself and to multiply in the roaches, but S. typhosa could not be isolated either from the droppings or from the roaches after death even though billions of cells were fed repeatedly. Serratia marcescens when fed to the insects resulted in positive excreta cultures within 48 hrs., and these organisms were excreted intermittently throughout the life of the insects. In some instances Serratia became so abundant in the body of the roaches that the insects turned a deep-red color in the upper half of their bodies and in their extremities. Death always followed shortly after this reddening appeared. Attempts to implant Torula rosea met with failure, but Saccharomyces cereviseae appeared to be a common inhabitant of many of the roaches.