Helping the pollinators

Sunday, May 22, 2011

Native leaf cutter bees sleeping on southern
beeblossom in the Garden's pine rockland section.

Most of our native bees are not social, as is the exotic honeybee. Instead, said bee expert Steve Buchmann, “think of them as single moms with families to feed.’’

Of the 4,000 bees native to the United States, 90 percent make nests in the ground, while the rest dwell in wood or plant cavities. A native bee mom digs a chamber, furnishes it with food for the young, then lays an egg on the packet of nutritious pollen/nectar, seals off the brood cell and flies away. The baby bees don’t have any eyes or legs. They have tiny heads and round, white bodies that take in food and excrete it. They, like butterflies and moths, go through complete metamorphosis before emerging from the ground (or dead trees) as adults.

Buchmann, who is a pollination biologist from Arizona and is a research associate at three institutions (the American Museum of Natural History, the Arizona-Sonora Desert Museum and the University of Arizona), is international coordinator for the Pollinator Partnership – an effort to rescue native bees from oblivion.

At the 31st Annual Conference of the Florida Native Plant Society, bees were the topics of two great talks and a film. Why? Because there has been a 40 percent to 60 percent decline in bees and flower flies here and around the world.

Eleven species of pollinators are extinct in the U.S., Buchmann said, and four common bumblebees have become “very rare.” Habitat loss, invasive plants and animals, pollution, pesticides and climate change all are bearing down on them.

A bee at work on varnish leaf.

Bees pollinate some 35% of our food crops and all of our native flowering plants. In an effort to utilize the pollinating talents of some of the 316 bees native to Florida, Akers Pence, at the University of Florida, has set up trials with a handful of watermelon and squash farmers in the state. He has planted both annual and perennial wildflowers in strips next to the farmers’ fields, kept tract of what native bees show up and how many in an effort to select the best wildflowers to help in pollination. Phase one has been completed, Pence said, and he found that 50 species of native bees appeared on such flowers as tickseed, Indian blanket, black-eyed susans and partridge pea. The next phase of his work will look at their effectiveness in pollination the crops, and convince farmers to plant wildflowers on the edges of their fields.

The earliest bees found in the fossil record appeared 130 to 140 million years ago, “around the same time the true dicots began to diversify,’’ Buchmann said. To keep them around, plant native plants, not hybrids; allow dead twigs and branches to remain on your trees an shrubs; keep some ground bare in your landscape (don’t mulch every single inch), and build bee condos, drilling holes in small wooden planks for bees that nest in cavities. The holes should be about 5/16th of an inch around and 3 to 5 inches deep. Use any good wood that is not green or pressure treated.

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