No abstract

Research Highlights: Our study establishes the biennial nature of flowering intensity as a life-time energy-conserving strategy; we show unexpectedly high flower:fruit ratios despite extensive predation of buds and flowers by insect larvae; ‘selective’ bud abortion may be a key annual energy-saving strategy. Background and Objectives: We aim to explain the strongly biennial flowering pattern of Eschweilera tenuifolia, an ecologically key tree species of Amazon blackwater-flooded forest, inundated for up to nine months annually, and with large flowers (6 cm in width). Materials and Methods: We quantified the insect infestation of central Amazonian Eschweilera tenuifolia buds and flowers; we measured nectar production from flower opening onwards, examined flower duration and monitored pollen theft. We tested the role of infestation in bud abortion, nectar production and fruit production initiation. Results: Our study shows extensive predation of buds and flowers by insect larvae, as well as selective abortion of heavily infested buds, and limited loss to pollen thieves which fed largely on infertile fodder pollen. Nectar production peaked in the morning, with no nocturnal nectar production recorded. Sucrose levels were similar to congeneric values (mean 37.4%), and near-constant during production. Flower duration (4–5 days) was longer than reported for other congenerics. Conclusions: Insect infestation of buds can play an important role in regulating flower:fruit ratios, thus setting limits on individual total seed set. Individual Eschweilera tenuifolia appear to invest highly in reproduction every second year. Extended flower duration may be a strategy to enhance pollination success, but increases overall reproductive investment. Abortion of heavily infested buds may minimize allocation of energy to malformed flowers, which have a lower chance of attracting pollinators, thus functioning as a short-term energy-saving strategy. Additionally, biennial flowering in E. tenuifolia is likely to be an energy-conserving response in a highly physiologically-challenging environment. Thus, E. tenuifolia exhibits energy-conservation strategies at two divergent temporal scales.

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.