Beans with bugs: Covert carnivory and infested seed selection by the red‐nosed cuxiú monkey

Abstract

Members of the Neotropical primate genus Chiropotes eat large volumes of immature seeds. However, such items are often low in available proteins, and digestion of seeds is further inhibited by tannins. This suggests that overall plant‐derived protein intake is relatively low. We examined the presence of insect larvae in partially eaten fruits, compared with intact fruit on trees, and examined fecal pellets for the presence of larvae. We found that red‐nosed cuxiú (Chiropotes albinasus) individuals may supplement their limited seed‐derived protein intake by ingesting seed‐inhabiting insects. Comparison of fruits partially eaten for their seeds with those sampled directly from trees showed that fruits with insect‐containing seeds were positively selected in 20 of the 41 C. albinasus diet items tested, suggesting that fruits with infested seeds are actively selected by foraging animals. We found no differences in accessibility to seeds, that is, no differences in husk penetrability between fruits with infested and uninfested seeds excluding the likelihood that insect‐infestation results in easier access to the seeds in such fruits. Additionally, none of the C. albinasus fecal samples showed any evidence of living pupae or larvae, indicating that infesting larvae are digested. Our findings raise the possibility that these seed‐predating primates might provide net benefits to the plant species they feed on, since they feed from many species of plants and their actions may reduce the populations of seed‐infesting insects. Abstract in Portuguese is available with online material.

Analysis of winter diet in Guizhou golden monkey (Rhinopithecus brelichi) using DNA metabarcoding data

“…However, there is variability in the sizes of different insects; larger insects may be intentionally preyed upon by monkeys, but smaller insects may be the product of secondary predation by monkeys (e.g., larvae‐infested fruits and shoots). In addition, Chiropotes albinasu s preferentially selects fruits whose seeds are infested with larval insects, which are protein‐rich and relatively easy to digest (Barnett et al., 2023). Therefore, smaller Diptera, Trichoptera and Hemiptera insects may have been accidentally acquired by R. brelichi while eating plants or drinking water; on the other hand, larger Coleoptera and Orthoptera insects may have been intentionally preyed upon by R. brelichi .…”