This, of course, would depend upon the strength of the colony, the number of flowers present, and weather conditions. There seems little doubt that B. campestris or Polish rape requires insects for cross-pollination and seed production. Downey et al. In the case of B. napus or Argentine rape, there is some question about the degree of benefit from insect pollinators. Downey et al.
Wind can carry pollen from one plant to another, but insects, particularly bees, are important.
Even so, he indicated that neither native bees nor honey bees were available in sufficient quantities for effective pollination of the large acreages of rape in Canada. Nothing was mentioned about transporting colonies to the fields that had low pollinator populations. The ratio of seeds per flower with bees present was 6.7 compared to 2.8 without bee visitation. Downey et al. He also stated that plants from cross- pollinated seeds were more productive.