What Kind of Bees Pollinate Tomatoes? Home Guides

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There is nothing like a vine-ripened tomato (Solanum lycopersicum, formerly Lycopersicon esculentum) warm from the sun to reward you for your gardening efforts. However, if the tomato flowers don't get pollinated, fruits won't form. The flower is built for a particular kind of bee pollination called buzz pollination, or sonication, where a strong-winged bee lands on the flower and vibrates its wings to dislodge the pollen from the anthers. Most modern cultivars grown outdoors also get pollinated by the wind shaking the plant to free the pollen. Tomatoes are grown as annuals in any U.S. Department of Agriculture plant hardiness zone.

Flower Structure Yellow tomato flowers hang down from the stem of the plant. The petals extend backward from the central reproductive structure, which consists of a cone made from five fused-together stamens that produce pollen from their anthers. The pollen comes out from pores at the tips of the anthers when the flower vibrates. Inside the anther cone is the female pistil, which is a slender style with a stigma at the tip. At the pistil base are carpels that develop into the tomato fruit after pollination. The tip of the stigma sticks out of the anther cone in long-styled flowers but is held inside the cone in short-styled flowers.

Kinds of Bees Honeybees are unable to buzz-pollinate tomato flowers. They don't have that behavior, and there's no reason for them to visit the flowers because the pollen is enclosed inside the anthers, unavailable for collection, and there is no nectar reward. Native bees like bumblebees (Bombus spp.) and mud bees (Anthophora urbana) buzz-pollinate tomato flowers. Sweat bees (Halictidae family) also pollinate tomato flowers, but seem to do so by chewing open the anthers.

Pollination Bumblebees and mud bees land on the bottom of the downward-pointing flower, grasping the anther cone with their legs. The pointed end of the cone rests against the underside of their abdomen. They then vibrate their wing muscles, and you can hear an audible buzz when they do this. This shakes the pollen down the anther tube, releasing it to land on the flower's own stigma and the bee. If it is a short-styled flower, it becomes self-pollinated. If it is a long-styled flower, the stigma presses against the bee's body and can be cross-pollinated with pollen on the bee's body from other plants.

Bumblebees Bumblebees are robust, hairy, black-and-yellow bees with dark wings. Some species have a red color on their abdomens. The queen bumblebee overwinters in a protected area and finds a nesting site in spring, usually an old mouse nest or a burrow, and begins the nest herself. Once she has worker bees, she stays home and lays eggs. The nest increases in size and toward summer's end, new queen bees and male bees emerge and mate. The inseminated queen then overwinters to repeat the cycle. Bumblebee colonies, usually containing the impatient bumblebee (Bombus impatiens), are often used to pollinate greenhouse tomatoes, with one hive able to work about half an acre of tomatoes. Workers are sometimes paid to use electric toothbrushes to pollinate flowers.

Mud Bees Mud bees are smaller than a honeybee and black, gray and white. They build nests underground in flat, bare soil areas or in vertical banks of soil. The female bee constructs cells at the ends of branching burrows. She puts pollen and nectar in each cell, lays an egg on the food and closes the cell, with the bee larva receiving no other maternal care. In favorable locations, hundreds of females make aggregate nests. Mud bees have a higher-pitched vibrating buzz than bumblebees. They are faster fliers than bumblebees or honeybees, and it's often hard to get a good look at them.

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