Pesticides affect pollinator abundance and productivity of sunflower (Helianthus annuus L.)

Pollination is considered one of the prime ecosystem services on the planet and is performed mainly by bees. The indiscriminate use of agricultural pesticides for pest control was evinced as one of the foremost causes of these pollinator declines. Sunflower crops demand an intense use of pesticides and, at the same time, are highly dependent on cross-pollination, essentially mediated by bees, for an increase in seed production. This study aimed to evaluate the impact of pesticides on richness and abundance of pollinators and productivity enhancement in sunflower. The study was carried out at the agua Limpa Experimental Farm located in the municipality of Uberlandia, Minas Gerais, Brazil, from May to August 2015. We conducted the study in two experimental crops of sunflower (Helianthus annuus L.). In one of them, we used the agricultural defensive bis(dithiocarbamate) for pest control, while in the other we only used a mechanical method. In both experimental crops, we quantified floral visitors during eight days, from 8 am to 4 pm. After maturation of inflorescences, we determined the mass of achenes and percentage of seed oil extracted. The abundance of floral visitors, the mass of fruits, and quantity of oil in the seeds were significantly lower after treatment with the pesticide, thus evidencing its negative effect on the sunflower productivity.