Co-pollination, constancy, and efficiency over time: small beetles and the reproductive success of Acrocomia aculeata (Arecaceae) in the Colombian Orinoquia



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Botany Letters


Acrocomia aculeata is under accelerated domestication due to the high yield and quality of the oils obtained from the fruits. Key details about its reproduction and fruit production, notably its dependence on cross-pollination, have not been thoroughly assessed. In the course of three successive reproductive seasons, we investigated the phenology, floral biology, pollination ecology, and reproductive efficiency of a natural population of A. aculeata in the department of Casanare, Colombian Orinoquia. We determined the effective pollinators among floral visitors based on their abundance, pollen carrying capacity, and constancy in association with receptive female-phase inflorescences. The studied population of A. aculeata exhibited a seasonal reproductive cycle, producing inflorescences during the drier months of December to April (peaking in March) and mature fruits from October to March. Each individual produces six to ten protogynous inflorescences, with a female phase that lasts ca. 12 h and a male phase extending for four to five days. A total of 48 insect species were observed in association with A. aculeata, averaging over 3500 visitors per anthetic female-phase inflorescence. Flower weevils (Andranthobius spp.; Derelomini) and small sap beetles (Mystrops sp.; Mystropini) were the most abundant visiting species and main pollinators, accounting for 90–95% of effective pollination services. Their high efficiency as pollen vectors was evident, as fructification rates reached on average 65.5% during the three years of study. Our findings support the assumption that co-pollination in A. aculeata evolved as a specialized strategy to maintain a high and temporally stable reproductive efficiency over time.