Geographical distribution of bees of the genus Bombus and associated flora in Rio Grande do Sul

Abstract

Pollinating animals are important for the pollination process, directly or indirectly influencing the production of various foods. Among the pollinators, the bees of the Bombus genus stand out for being efficient pollinators of several agricultural crops. Observations of visitation and feeding behavior of pollinators in the field are important to establish the relationship between Bombus species and the plants exploited by them, since research shows and proves the population reduction of these bees. With this, the objective was to carry out a survey of the species of the genus Bombus and their geographic distribution in the state, as well as their relationship with host plants and floral resources. The research to identify the Bombus species and the flora associated with them took place in 48 municipalities covering several regions of the state. Collections were carried out in spring and summer from 2017 to 2019, directly in the floral resource visited by Bombus spp. during foraging. Two species, Bombus (Thoracobombus) morio Swederus (1787) and Bombus (Thoracobombus) pauloensis Franklin (1913), were identified in 32 municipalities, associated with 17 plant species belonging to 11 families. B. morio was collected visiting floral resources of 14 plant species (09 native, 04 introduced and 01 cultivated) belonging to 09 families and B. pauloensis was collected visiting floral resources of 11 plant species (05 native, 04 introduced and 02 cultivated), belonging to 08 families. In 16 cities sampled, the presence of Bombus was not verified. It was found that Bombus species are widely distributed in the state, occupying different ecological systems, and that the species B. pauloensis has greater adaptability to different temperature ranges (10.88–15.5ºC; 15.5–20.5ºC ; 20.5–25.5ºC; 25.5–28.5ºC), while B. morio was found in greater quantity (69%) in the temperature range of 20.5ºC and 25.5ºC.