An Arizona bumblebee is 500 times faster than honey bees in pollinating flowers. The carpenter bee, another U.S. native found in Arizona, is very hardy, surviving desert conditions. These are two examples of native bees that have commercial potential as crop pollinators. Honey bees from Europe annually pollinate U.S. crops worth about $8 billion, but growers may need more help from other bees in the future. Scientists are now matching bees with crops they pollinate best. Pollen bees provide an alternative to honey bees, which face danger on at least two fronts. In many parts of the country, mites attack honey bees' breathing tubes. And, in the southwest, an Africanized strain crossbreeds with the European honey bee. The offspring are more defensive--thus more likely to sting and more difficult to manage--and are less effective pollinators. Non-honey bees are not affected by mites or Africanized bees.
Carl Hayden Bee Research Center, Tucson, AZ
Stephen L. Buchmann, (602) 670-6481

Plants probably aren't as thirsty as they used to be. The reason: rising levels of carbon dioxide (CO2) in the atmosphere. Plants take in needed CO2 through leaf openings called stomates, but gaping stomates let precious water escape. Researchers say today's higher CO2 levels-- approximately 360 parts per million (ppm) vs. about 280 ppm a century ago--mean stomates need not open as wide, so less water is lost. In greenhouse tests, acacia plants grew in air with 350 ppm, 700 ppm or 1,000 ppm of CO2. Over five months' time, the plants all used about the same amount of water. But the acacia in 1,000 ppm of CO2 grew an average of 23 feet, compared with 15 feet for plants in 700 ppm and only about five feet for plants in 350 ppm. Rising CO2 levels during the past century could help explain how rangeland brush has proliferated in western states as plants' increased water use efficiency enables them to grow in areas where water is scarce.
Grassland Protection Research, Temple, TX
Herman S. Mayeux Jr., (817) 770-6533

Cantaloupes can lose their sweet taste if heavy rains fall just before harvest, often leaving them unmarketable. But researchers found this shouldn't happen if growers can harvest the melons within a day or two after a heavy rain. Or, if growers can wait a week, the fruit's sugar stocks will rebuild. Growers have thought that heavy rain dilutes the sweet taste when the fruit takes in excess water via the roots. Scientists now blame a sugar shortage rather than a water surplus. The results of laboratory studies by ARS and North Carolina State University were confirmed in field tests by ARS and the University of Arizona. After heavy rain, the roots stop working. They can't take up needed oxygen from rain-saturated soil. This shutdown signals leaves to halt photosynthesis, the plant's mechanism for using solar energy to produce sugars. The reduced sugar content shows up about four days after the heavy rain. Meanwhile, sugars already in the fruit have begun breaking down. The new findings will help save the melons' sweet taste. Plus, the field studies provide new information on when drip or furrow irrigation will help or hinder melon sweetness and other qualities.
Crop Quality and Fruit Insects Research, Weslaco, TX
Gene Lester, (210) 565-2647
Plant Physiology and Photosynthesis, Raleigh, NC
Steven Huber, (919) 515-3906

Last Updated: December 13, 1996
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