Growth and food utilization parameters of germ-free house crickets, Acheta domesticus
Kaufman, M.G.; Klug, M.J.; Merritt, R.W.
Journal of Insect Physiology 35(12): 957-967
Conventional and germ-free larvae of Acheta domesticus are reared under three diet conditions varying in nutritional quality in order to assess possible roles of the gut microbial community in these insects. Although growth rates, adult size, and maturation times were nearly identical for the two groups across all diet treatments, conventional larvae digested and converted food into biomass more efficiently than germ-free larvae in all cases. Enhanced food utilization efficiency in conventional animals was related to the scavenging of soluble carbohydrates by gut microorganisms. Comparisons of enzymatic activity in both groups also indicated that the gut bacteria increased the level of several carbohydrase classes in conventional larvae and were the sole source of a -galactosidase activity. The microorganisms may also have aided in conservation of nitrogenous compounds, but this was influenced by age and diet. Microbial metabolism of uric acid could not consistently be related to overall food utilization or nitrogen economy, and did not appear to be an important means of conserving nitrogen.