The investment of nitrogenous materials by female and male German cockroaches Blattella germanica (L.) into their progeny was examined. Adult females maintained on dog food invested 34% of their dry mass and 26% of their nitrogen into an oothecae during their first gonadotrophic cycle. Females maintained on a low- (5%) protein diet and injected simultaneously with [3H]leucine and [14C]hypoxanthine incorporated less [3H]leucine-derived radiolabel in their oothecae than those on a dog food diet (25% crude protein). Females on the low-protein diet incorporated more [14C]hypoxanthine-derived material (primarily as [14C]urates) into their oothecae than they retained in their bodies. Stored [14C]urates were metabolized more readily by females on the low-protein diet. Oothecae obtained from females provided with an [15N]urate-amended diet contained at least four 15N-enriched amino acids, which supports the hypothesis that urates are utilized as a nitrogen resource in these insects. Dietary effects on paternal investment were also found to be significant. Females fed a low-protein diet and their oothecae contained 63% of the radiolabel made available to them at mating when paired with males injected simultaneously with [3H]leucine and [14C]hypoxanthine, whereas dog-food-fed females and their oothecae contained only 17% of the total radiolabel made available to them at mating.

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