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Leafcutter bees working to keep alfalfa seed profitable

It’s a crop-eat-crop world in California agriculture with the wide range of cropping options available to growers battling for ground against rising costs and dwindling water supplies.

Alfalfa for seed is economically hanging in thanks to a tiny insect, the leafcutter bee, which has proven to be a worthy teammate of the honey bee.

“Economically seed alfalfa cannot compete with other crops without the leafcutter bees,” says longtime alfalfa breeder Bob Sheesley of S&W Seed, Five Points, Calif.

Using leafcutters to complement seed alfalfa’s traditional pollinators, honey bees, increases yields 250 pounds to 300 pounds per acre, according to Sheesley.

Leafcutter bees, common pollinators for alfalfa seed in the Pacific Northwest and for hybrid canola in Canada, have put some growers back in the alfalfa seed business.

“We grew alfalfa seed in 1986 and 1987 and didn’t do well,” said John Diener, a Five Points grower who resumed growing the seed seven years ago because of the added pollination efficiency of the leafcutter bees.

Shannon Mueller, University of California Cooperative Extension agronomy farm advisor in Fresno County, says leafcutter bees are more efficient pollinators than the honey bees. The honey bee is reluctant to trip the reproductive structure of the alfalfa flower, wary of being struck in the head. “The leafcutter bee does not seem to mind that,” Mueller said.

Pollination is a byproduct of the honeybee’s visit to the alfalfa flower where it is actually foraging for nectar. In the process, it accidently pollinates.

Leafcutters forage for pollen; therefore, they are more efficient pollinators.

Growers continue to use honey bees because they are less susceptible pesticides used on alfalfa than leafcutters. When pesticides are to be sprayed on a field, honey bee hives are usually covered with something like a cotton module cover during the spray period and shortly thereafter.

Leafcutters, which are housed in trailer-mounted domiciles, must be removed from the field for pesticide sprays, sometimes for several days to prevent bee deaths from residues. Honey bees do not like working in alfalfa that is being irrigated. Leafcutters do not mind it.

Growers started importing leafcutters from Canada several years ago when concerns arose about Africanized honey bees overwhelming more docile honeybees. The honey bee also has had its share of decline problems with mites, colony collapse and other issues, prompting growers to look at different pollinators. Leafcutters have so far escaped survival issues like those faced by honey bees.

Outside his office at his Red Rock Ranch, Diener has about 40 wooden trailers used to house leafcutters during pollination. Honey bees work out of wooden hives.

In the past two years, growers in the Imperial Valley, seeing the successes in the arid San Joaquin Valley, began adding the leafcutter to their arsenal. So did some growers in Arizona.

That demand for leafcutters, said San Joaquin grower Chuck Deatherage, helped drive up the cost of the bees, most of which come from Canada.

Demand has doubled in California, according to Deatherage. The current price for leafcutters is from $85 to $100 per gallon.

The bees come pre-incubated from Canada in larvae containing cells and placed in domiciles with about 1.5 days until hatch.

While leafcutters are more efficient pollinators than honey bees, they require more intensive management. This is because seed alfalfa seed growers also become beekeepers, responsible for the upkeep and well being of the bees in the domiciles. With honey bees, professional beekeepers take care of the hives.

Leafcutters are solitary bees and don’t produce colonies as honey bees do. Individual female leafcutter bees do the rearing — creating nest cells and providing their young with food.

Growers provide these nests, which are styrofoam blocks with soda-straw size holes punched in them. Leafcutter females lay eggs, pollen balls and alfalfa leaves in these holes, creating as many as six or seven larvae cells in each hole.

These styrofoam blocks are then stored over the winter. In the spring the cells are punched out and spread out on trays in the domiciles. They hatch in 21 to 23 days.

“In the Valley we get only about a 25 percent hatch in the spring. The cells purchased from Canada get a 90 to 100 percent hatch,” says Sheesley.

In California, production of certified alfalfa seed was up slightly in 2008 to 43,200 acres, producing 22.8 million pounds of seed, Mueller said. “It had been dropping and at its lowest was 26,000 acres,” she said. At its peak, there were 100,000 acres of seed alfalfa produced in the state in 1999.

The crop was a relatively profitable one in 2008. Diener said growers who received $1.75 to $2 a pound in 2007 earned between $2.10 and $2.50 last year.

The average yield per acre is 528 pounds in California. Yields tend to be higher – as much as 800 to 1,000 pounds – in the San Joaquin Valley.

A significant percentage of the seed produced in the San Joaquin Valley is exported.

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