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Science Update
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| Saying "No"
to Plum Curculio
A telltale, crescent-shaped blemish on apples, apricots, cherries, peaches,
pears, and plums is all it takes to signal an invasion by plum curculio
weevils, Conotrachelus nenuphar. The blemish indicates that a
quarter-inch-long, brown-and-gray, adult female has laid her eggs under the
skin of this developing stone or pome fruit, causing scarring and ultimately
reducing yield.
Now scientists have identified a natural odor, or pheromone, released by the
male curculio weevil that attracts both males and females. Placing traps baited
with this chemical—grandisoic acid—into orchards at blossom time drew
weevils to the traps. Work is now needed to add other volatile compounds, such
as fruit odors, to increase the pheromone's attractiveness enough to capture
more weevils.
One day, baited traps may become reliable tools to help fruit growers monitor
this pest's arrival in their orchards, so they'll know whether insecticides are
necessary and when to spray them to prevent significant damage.
Fred J. Eller, USDA-ARS
New Crops and Processing
Research Unit, Peoria, Illinois; phone (309) 681-6232. |
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Two newborn piglets.
(K9455-20)
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Injection Boosts Piglet Weight
A one-time injection of an anti-inflammatory agent used in veterinary and human
medicine may help newborn pigs get off to a better start. Repeated small-scale
tests have shown about a 12-percent faster gain in body weight during the first
18 days of life in piglets given dexamethasone. It's a synthetic version of a
type of hormone—a corticoid—that is naturally produced by animals
under stress.
Cutting by just one day the length of time it takes pigs to reach market weight
could boost swine producers' annual income by tens of millions of dollars. So
researchers want to see whether within the first hour of birth is the best time
for treating newborn pigs with dexamethasone. And they are beginning to test
the one-time treatment's long-term effects on pigs. They do this by measuring
the rate of weight gain, amount of feed consumed per pound of gain, and body
composition at market weight.
Jeffrey A. Carroll, USDA-ARS
Animal
Physiology Research Unit, Columbia, Missouri; phone (573) 882-6261.
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| Peanut Butter Free of
Trans Fats
Suggestions that this popular lunchbox staple contains a kind of fat that
increases risk of cardiovascular disease now appear unfounded. Researchers had
11 brands of peanut butter—including store brands and "natural"
brands—tested in a commercial laboratory against paste made from freshly
prepared roasted peanuts. The lab found no detectable trans fats in any of the
samples, with a detection limit of 0.01 percent of the sample weight.
This means that a 32-gram serving of any of the 11 brands could contain from
zero to a little over three-thousandths (0.0032) of a gram of trans fats
without being detected.
While current regulations don't require food labels to disclose trans fat
levels, they do require disclosure of saturated fat levels at or above
five-tenths (0.5) of a gram—a level that's 156 times higher than this
study's detection limit for trans fats.
Peanut butter has plenty of unsaturated fatty acids, with oleic acid the most
abundant. It's thought to be a beneficial fat and, in these analyses, ranged
from 19 percent in one of the store brands to 27 percent in one of the
natural-type spreads.
Palmitic acid, the most abundant saturated fatty acid, weighed in at about 5
percent among all brands tested.
Timothy H. Sanders, USDA-ARS
Market Quality
and Handling Research Unit, Raleigh, North Carolina; phone (919) 515-6312.
Raindrops on Cotton Can Cut Fiber Yield
Just a little bit of the wet stuff can wreck pollen and leave cotton flowers
unpollinated. Sterile flowers soon fall off the plant without forming the bolls
that are the source of cotton textile fibers.
Within only 30 to 60 seconds of encountering a drop of water, wet pollen grains
swell up and pop open, dumping their contents prematurely. Greenhouse tests
showed a 55-percent loss in seed set after just one squirt of water per test
flower.
Researchers are comparing conventional overhead sprinkler irrigation fields
with those watered by "drop socks" attached to sprinklers close to
the ground. The drop socks minimize waterspray on plants and dramatically
reduce the yield losses associated with water-induced pollen death. So watering
cotton plants from below through drip, furrow, or drop-sock irrigation may help
ensure adequate pollination for optimal yields.
John Burke, USDA-ARS
Plant Stress and
Germplasm Development Research Unit, Lubbock, Texas; phone (806) 749-5560.
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| "Science Update" was published
in the November
2001 issue of Agricultural Research magazine.
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