Physiological processes related to nitrogen excretion in cockroaches

Several patterns of uric acid voiding exist among various cockroach species. The impact of dietary nitrogen levels on these patterns has now been examined. Blattella germanica, Supella longipalpa, and Latiblattella inornata do not void uric acid even when maintained on diets containing 10.6% nitrogen for up to 30 days. Two species of Nahublattella void some uric acid on that diet, but high mortality was observed by 15 days. Parcoblatta fulvescens voids increasing amounts of uric acid as formed pellets when dietary nitrogen is increased, and suffers no untoward effects. The partitioning of injected 14C-purine (hypoxanthine) by Parcoblatta was shown to occur first by conversion to 14C-uric acid. Thereafter, 14C is found in evolved 14CO2, feces, egg cases, and whole body. The partitioning of 14C is influenced by the level of dietary nitrogen available. On a nitrogen-restricted diet, larger amounts of 14CO2 are evolved but little 14C occurs in the feces. When nitrogen is abundant, reduced amounts of 14CO2 are evolved and more 14C is voided with the feces. 14C-containing compounds, including 14C-uric acid, are incorporated into egg cases. Radiolabel remaining in the injected insects at the end of the experiment was also influenced by the dietary regime. These results are discussed in relation to the flow of uric acid through Parcoblatta and its utilization by this insect.