Pollen sources used by the stingless bee Schwarziana quadripunctata in a coffee-growing landscape

Abstract

Research on the food sources used by bees in agricultural landscapes is crucial to promote pollinator conservation measures in and around cultivated areas. This investigation aims to identify and quantify the pollen resources exploited by Schwarziana quadripunctata (Lepeletier 1836), assessing the trophic niche of this bee in agricultural areas with coffee plantations. Pollen analysis was conducted based on the pollen load of the corbiculae of 70 bees, sampled during the flowering period of two species of coffee trees in commercial plantations located in Rio de Janeiro, Minas Gerais and Espírito Santo states, Brazil, in 2019 and 2021. A total of 78 pollen types from 23 botanical families were identified, with Coffea arabica and Coffea canephora comprising 92% of the samples. Cestrum sp. (2.3% – Solanaceae), Fabaceae sp. 1 (0.9%), Solanum sp. (0.75% – Solanaceae) and Chamaecrista sp. (0.71% – Fabaceae) were the next most prevalent. The dominance of the coffee tree pollen confirms the floral constancy of S. quadripunctata during periods of intense flowering. Excluding coffee pollen, the most represented families were Solanaceae (46.6% of the samples), Fabaceae (27.5%), Rubiaceae (8.51%), and Meliaceae (2.53%). The findings reveal that S. quadripunctata actively forages from sources other than coffee, even during the intense flowering of these plants, highlighting the importance of floral resources in the proximity of plantations. The use of pollen sources beyond the coffee tree highlights the importance of conserving nearby forest fragments and maintaining a diverse array of plants surrounding coffee trees even during coffee flowering.