Observations on the pollination of lucerne ( <i>medicago sativa</i> linn.)

Abstract

Abstract Observations were made on the role of the honey bee and the bumble bee in the pollination of lucerne ( Medicago sativa Linn.) in the North Canterbury, North Otago, Central Otago, and Blenheim districts of New Zealand over two seasons. The relation between tripping and lucerne pollination was also studied. Pollination of crops averaged only 10 per cent. Pollination by insects in the field is thought to be due to accidental tripping by nectar‐collecting honey bees, and consistent tripping by bumble bees. No other insects appear to be important as pollinators. A cage experiment in which honey bees and bumble bees were excluded suggested that automatic tripping was of little importance, at least in the Lincoln and Blenheim areas. Greatly increased pollination occurred in cages with high honey bee densities. This increase is attributed to a higher tripping rate in the cages, as high bee densities in the field, where little tripping occurs, are not accompanied by increased pollination. It was considered that in (he majority of crops studied the honey bee was the most important pollinator. There was no evidence that any increase in hive concentration above one(ac would improve pollination.