Print PageRecent studies of animal nutrition have demonstrated how macronutrients in food affect the behaviour, growth, reproduction and longevity of a wide range of animals. However, relatively few studies have examined the nutritional ecology of carnivores. One obstacle to the study of carnivore nutrition is the difficulty of experimentally manipulating the nutrient content of live prey items. We developed a new method of quantitatively manipulating the nutrient content of arthropod prey for carnivores. Locusts, Locusta migratoria used as prey, were injected with solutions of lipid or protein and then fed to spiders, Argiope keyserlingi.
Results/Conclusions
Spiders ingested a similar overall biomass of food on all treatments (sham-injected, lipid-injected and protein-injected). In the sham injection treatment, all of the ingested food was locust tissue. However, when spiders were fed injected locusts, almost half of the nutrients ingested by the spider were from the injection. In addition to ingesting the injected nutrients, spiders were able to assimilate injected nutrients. In a short term growth experiment, spiders assimilated approximately 60 percent of the nutrients that they ingested regardless of whether the nutrients were from locust tissue or a combination of locust tissue and injection. This method allows for explicit and quantitative manipulations of a wide range of nutrients (e.g., carbohydrate, lipid, protein, specific amino acids, micronutrients) in live prey for carnivorous arthropods.
