L. Zurek et Ba. Keddie, CONTRIBUTION OF THE COLON AND COLONIC BACTERIAL-FLORA TO METABOLISM AND DEVELOPMENT OF THE AMERICAN COCKROACH PERIPLANETA-AMERICANA L, Journal of insect physiology, 42(8), 1996, pp. 743-748
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