CONTRIBUTION OF THE COLON AND COLONIC BACTERIAL-FLORA TO METABOLISM AND DEVELOPMENT OF THE AMERICAN COCKROACH PERIPLANETA-AMERICANA L

An examination of profiles of volatile fatty acids (VFAs) and methane as end products of bacterial metabolism was used to assess the physiol ogical significance of the colon and colonic anaerobic bacterial micro flora during development of the American cockroach Periplaneta america na. The effects of reducing intestinal bacterial populations with an a ntibiotic, metronidazole, were evaluated by measuring VFAs concentrati ons, cockroach weight gain and development time (the length of nymphal period). Supplementary feeding of VFAs to treated animals was also ev aluated. During normal development VFAs concentrations peaked during t he first thirty days, then diminished slightly and remained relatively stable. Metronidazole treatment reduced bacterial populations in the colon, significantly lowered VFAs concentrations, reduced cockroach we ight gain and extended the development time. Supplementary feeding of VFAs partially compensated for the effects of the antibiotic treatment (as measured by cockroach weight gain and development time). These re sults suggest a significant contribution of bacterial volatile fatty a cids to cockroach metabolism, especially during the insect growth peri od. The significance of the colon as the major site of bacterial colon ization is also discussed. Copyright (C) 1996 Elsevier Science Ltd