Assessing important floral resources supporting two species of Exomalopsis (Apidae) in agricultural cultivation areas: insights from pollen load analysis

Pollination plays a vital role in maintaining ecological functioning of ecosystems, and bees are the main pollinating insects in natural and agricultural areas. Identification of bee food sources can be carried out directly by observing their visits to flowers, or indirectly by analyzing the pollen they carry. Pollen analysis is employed to determine the breadth of the bees' dietary niche and understand the relationship between flower traits, pollen grains, and floral resources. While Exomalopsis females were previously recorded as pollinators of Solanaceae species, information regarding their trophic niche in agricultural areas remains limited but is essential for the management of these wild pollinators. In this study we accessed the floral resources used by two Exomalopsis species (E. analis and E. auropilosa) through pollen analysis in their scopae, using cultivated Capsicum cultivars (Solanaceae) as target plants. Pollen samples from 56 Exomalopsis females (21 from E. analis and 35 from E. auropilosa) revealed 58 pollen types belonging to 24 botanical families, with the highest values found for Fabaceae, Asteraceae, Euphorbiaceae, and Rubiaceae. E. auropilosa showed greater pollen type richness (46) with 3-10 types per bee, while E. analis had 43 types with 3-13 types per individual. Capsicum, a pollen, and nectar source constituted approximately 77% of the pollen loads. Most of other plant species identified were arboreal and provided nectar to these pollinators. Trophic niche overlap between Exomalopsis species was low. The conservation of wildflowers surrounding pepper cultivations is essential for maintaining these two important pollinators in agricultural areas. Additionally, areas with bare soil can contribute to the persistence of Exomalopsis populations.