Apis mellifera visitation enhances productivity in rapeseed

Rapeseed (Brassica napus L.) is the second most produced oilseed crop in the world. It provides a high-quality nutrient for pollinating insects, and pollination, in many cases, increases crop yield. Although a large number of species visit rapeseed crops, Apis mellifera (Hymenoptera: Apidae) is the most frequent, abundant, and with the highest pollination potential. Our aim was to evaluate the effect of A.mellifera on the different yield components of Brassica napusL. (cv. Rivette). The hypothesis of the study was that the presence of pollinators would increase rapeseed crop yield and improves maturation uniformity. Four trials were conducted (one in 2013, two in 2015, and one in 2016) in commercial rapeseed crops, using pollinator exclusion tents placed during the flowering period. A randomized complete block design with two treatments and six replications during 2013 and three replications during 2015 and 2016 was used. Treatments consisted of exclusion tents with the addition of an active beehive (WITH) and without a beehive (EXCLUDED). WITH treatments showed greater uniformity on siliques maturation and a lower proportion of flowers at maturity. Rapeseed yield was determined by the site (season and farm) (P < 0.0005) and treatments (WITH or EXCLUDED) (P = 0.0482), with no interaction between them (P = 0.1217). Grain yield in WITH treatments was 14% higher than in EXCLUDED treatments (2089 vs. 1836 kg ha(-1)). In 12 out of 15 (80%) experimental units, WITH treatment yields were higher than EXCLUDED treatments. Results show that A.mellifera can increase rapeseed yields, despite a high rate of self-fertilization.