Diversity of visitors to the flowers of two palm species of the genus Oenocarpus in the Province of Napo, Ecuador

Abstract

In Ecuador, between the foothills of the Andes and the well-drained terra firme forests of the Amazon, there are two useful palm species, Oenocarpus bataua and O. mapora, which differ mainly in size. Both species are negatively affected by deforestation and land conversion for agriculture and cattle ranching, altering the structure and functioning of ecosystems. Management and restoration plans are therefore needed. To contribute with local knowledge of the species, we studied the diversity of flower visitors of both species in 9 sites in Napo Province during the flowering seasons of 2021 and 2022. We collected 16 inflorescences and measured the length, number of rachillae and flowers of each and correlated them with the richness and abundance of their floral visitors. Finally, we calculated a similarity index between species and developed an interaction network to observe associations between their inflorescences and flower visitors. We found 89 morphospecies of flower visitors, 77 in O. bataua and 51 in O. mapora, and 19 morphospecies are potential pollinators because they are active during the staminate and pistillate phases. This is the first report of flower visitors of O. mapora in western Amazonia, and it shared 40% of flower visitors with O. bataua, which is a higher percentage than previously reported between O. bataua and other species of the genus. The most common morphotypes in the staminate phase were Discocoris drakei, Notesia sp.2, Andrathobius sp.1, Mystrops vasquezi, and in the pistillate phase: D. drakei, A. bicarinatus and Phylotrox sp.1. These insect species should be taken into consideration when monitoring the status of the palm species and for conservation plans.