What Kind of Bees Pollinate Tomatoes?

Wind Pollination

• Tomatoes will self-pollinate in a strong breeze. In fact, any activity that causes the flower to vibrate, knocking the pollen off the flowers, will cause the tomato bloom to release pollen. It is important that copious amounts of pollen reach each ovary of the flower for full-sized fruits. Where areas on the stigma don't receive enough pollen, it causes holes or dimples to form in the fruit, a phenomenon called "cat facing." In nature, tomatoes don't produce nectar and don't attract pollinators because they depend on the wind.

Hand Pollination

• Greenhouse-grown tomatoes historically have had to be hand pollinated. To hand pollinate, each flower must be visited by a gardener who uses one of two methods of pollinating. The first method is to grab the stem below the flowers and shake it. This method works on many blooms at one time but may not be as complete as the second method. The second method is to use your index finger, assisted by building pressure against the thumb first, to flick each flower three times individually. This is slightly more time-consuming than the shaking method, and it is necessary to mentally keep track of which flowers have been flicked. An alternative method is to use an electric toothbrush against each blossom.

Bumblebees in the Greenhouse

• Because tomatoes don't produce nectar, they don't attract as many pollinators as other plants. Bumblebees, ground-dwelling communal bees, will visit tomatoes for their pollen. Dr. Roland de Jog accidentally discovered the bumblebee's efficiency at pollinating tomatoes when he was looking for a good place to raise his "pet" bumblebees and used his friend's tomato greenhouse, according to Richard Gerhart from International Technology Services. Greenhouses employ two species of bumblebees in the United States for tomato fertilization: Bombus impatience and Bombus occidentalis; the former species is employed east of the Rockies and the latter species is used west of the Rockies. Outside of the United States, greenhouses use Bombus terrestris for tomato pollination. Bumblebees are large, with orange to yellow hairy striped abdomens; often, their back legs bear yellow pollen baskets. Bumblebees can, and will, sting to defend a nest and can sting repeatedly but are generally nonaggressive.

Carpenter Bees

• Growers are also breeding carpenter bees, Xylocopa species, for use in tomato greenhouses. Their thoracic muscles are strong and they vibrate their whole bodies when collecting pollen. Carpenter bees have a shiny black abdomen as opposed to the fuzzy yellow striped abdomens of bumblebees. Both species prefer to pollinate in the morning hours. While bumblebees nest underground, carpenter bees nest within pieces of wood. Neither bumblebees nor carpenter bees are as aggressive as the honeybee; carpenter bees, being solitary, are not territorial in the least. In addition, only female carpenter bees have stingers, further reducing the chances of a bee stinging a greenhouse worker.