Population patterns of two generalist forager bees on canola: effects of sowing season, plant genotype, meteorological factors, and coabundance

Abstract Canola, Brassica napus Linnaeus var. oleifera, is one of the main oilseeds grown in the world. Pollination is required to ensure an acceptable yield. Among the main bee pollinators (Hymenoptera: Apidae) occurring in canola in southern Brazil are Apis mellifera (Linnaeus) (Apidae: Apini) and Trigona spinipes (Fabricius) (Apidae: Meliponini). Plant genotype, sowing season, meteorological factors, and abundance of competitors can influence the foraging rate of A. mellifera and T. spinipes in canola, which will impact yield. We evaluated the effect of plant genotype, sowing season, and meteorological factors on the abundance of foraging bees, as well as their coabundance and impacts on canola yield. Under the conditions of the study, we did not observe significant variation between genotypes and sowing season on bee abundance and canola yield. We note that the impact of temperature and relative humidity are important predictors of abundance of A. mellifera and T. spinipes. The temperature and relative humidity effects, however, differed according to bee species. Coabundance patterns indicated no evidence of competitive exclusion. Higher canola yields were obtained when both bee species had high population abundance.