title: Sexual differences in postingestive processing of dietary protein and carbohydrate in caterpillars of two species.
abstract: Previous studies indicated that female Heliothis virescens and Estigmene acrea caterpillars use both feeding and postingestive processing as mechanisms to meet nutrient demands. We present utilization and nutrient budget data on the postingestive partitioning of nutrients into pre- and postabsorptive components. Both species utilized carbohydrate efficiently except at very high ingestion rates. Of the carbohydrate utilized, more was unaccounted for as intake increased, and we assume the material unaccounted for served as a respiratory substrate. In contrast, the pattern of nitrogen utilization differed between the species. Larval H. virescens efficiently retained nitrogen except at very high ingestion rates, whereas E. acrea progressively increased nitrogen egestion in response to increased nitrogen ingestion. Overall, females of both species utilized nitrogen more efficiently than did males at most ingestion levels, thus contributing to the greater protein-derived growth we previously reported. In addition, for H. virescens, protein and amino acids accounted for a small proportion of fecal nitrogen so that most of the fecal nitrogen was of a postabsorptive nature. In contrast, nitrogen excreted by E. acrea could be partitioned into both pre- and postabsorptive components. The manner of postingestive processing by these two species reflects differences in their larval diet.
authors.affiliation: Interdisciplinary Program in Insect Science, 410 Forbes Building, University of Arizona, Tucson, AZ, 85721, USA. atelang@ag.arizona.edu
authors.forename: Aparna
authors.initials: A
authors.lastname: Telang
authors.forename: Norman A
authors.initials: NA
authors.lastname: Buck
authors.forename: Reginald F
authors.initials: RF
authors.lastname: Chapman
authors.forename: Diana E
authors.initials: DE
authors.lastname: Wheeler
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion / Q000502:physiology*; D007814:Larva / Q000378:metabolism*; D009036:Moths / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D009751:Nutritional Requirements; D019518:Postprandial Period / Q000502:physiology; D012727:Sex Characteristics; D013045:Species Specificity
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D009584:Nitrogen