Evaluating the nutrition of Orthoptera and other insect prey for Weddell’s saddleback tamarin (Leontocebus weddelli)

Abstract

Many primate species consume insects as part of their regular diet, yet few researchers have systematically collected them and analyzed their nutritional content. In this study, we developed protocols for collecting and analyzing prey items consumed by Weddell's saddleback tamarins (Leontocebus weddelli), focusing on Orthoptera (crickets, grasshoppers, and katydids) which have been documented to be a central component of their diet. We used five methods to collect insect prey (pitfall, sheet, water, moth trap and manual capture) at a field site in northwestern Bolivia over the course of two months. In total, we collected 1302 insect samples, which we photographed, weighed, dried, and sorted into nine taxonomic groups (Acrididoidea/Eumastacoidea, Blattodea, Cicadoidea, Gryllidae, Lepidoptera, Mantodea, Phasmatodea Proscopiidae, and Tettigoniidae). We then analyzed the samples for their macro- and micro-nutrients. We found that the manual capture method was the most effective for capturing orthopterans. Our analyses showed that the samples primarily contained crude protein (52.63-78.54 % dry matter (PCDM)), chitin (12.05-27.26 PCDM) and fat (4.63-15.6 PCDM). The samples also contained high levels of a wide variety of minerals, including iron (42-655 parts per million (ppm)), zinc (85-554 ppm), and manganese (37-1200 ppm). These results indicate that orthopterans and other Neotropical insects can serve as important sources of macro- and micronutrients for tamarins. Given the variation in nutrient content among taxa, we recommend that researchers collect and analyze insects that most closely resemble the prey consumed by their study subjects to determine their nutritional value, and not assume equivalent nutritional composition across species, higher taxa, or life stages. Given the success of using night walks with manual capture for collecting Orthopterans, we recommend that other primatologists use this method to allow for cross-site comparisons of insect nutrition.