Nutrient composition of selected whole invertebrates

Although nutrient requirements of insectivores have not been specifically determined, detailed chemical analysis of invertebrates used in zoo feeding programs is essential for evaluating nutritional adequacy based on domestic animal models. Additionally, such data can provide valuable suggestions for future research priorities. Proximate composition, fat-soluble vitamins, and minerals in mealworms (Tenebrio molitor and Zophobas morio), crickets (Acheta domesticus), waxworms (Galleria mellonella), fruit flies (Drosophila melanogaster), and earthworms (Lumbricus terrestris) were determined. All species had a water content >50% of their body weights. Larval invertebrates had higher fat content (x >30% dry matter [DM]) than adult species. Total nitrogen (N) ranged from 5.2±1.1% DM (earthworms) to 10.3±0.4% DM (adult crickets), whereas chemically bound N comprised 3–10% of total N in all invertebrates. Neutral detergent fiber, used as a measure of chitin, averaged 15.3±3.6% DM for all species except wild-caught earthworms, which were higher (51% DM). Vitamin E concentrations ranged from 15±3 IU/kg DM (mealworms) to 509±232 IU/kg DM (waxworms). Vitamin A concentrations were undetectable (fruit flies) to low in all samples; none met the recommended dietary vitamin A concentrations established for domestic carnivores. Insects had low calcium concentrations (x = 0.11%) and imbalanced calcium:phosphorus ratios except for pinhead crickets. Insects sampled contained sufficient concentrations of Cu, Fe, Mg, P, and Zn to meet known requirements of domestic birds and mammals, whereas supermealworms and waxworms contained deficient levels of Mn. Earthworms appeared to meet dietary mineral requirements, based on domestic bird and mammal recommendations. Zoo Biol 17:123–134, 1998. © 1998 Wiley-Liss, Inc.