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A parasitic fly that kills fire ants in South America awaits new tests
to see if it can control the pest in the United States. Preliminary
field tests in Brazil point to Pseudacteon flies as a natural way
to combat the stinging fire ants, native to South America and invaders of
11 southern states and Puerto Rico. Studies show that the fly attacks
only fire ants but does not attack beneficial insects or humans. In
Brazil, the flies hover a quarter-inch above the ants, ready to attack.
Once a female fly finds a large worker ant, she swoops down and--with her
needle-like ovipositor--lays an egg either on the ant or inside its upper
body. Then she flies away, before the ant can counterattack. The fly
maggot gradually develops after working its way through the ant's neck
into the head. Just before it reaches adulthood, the maggot eats
everything inside the ant's head. Then an enzyme dissolves the tissue
connecting the ant's head to its body--causing the ant's head to fall off
with the developing maggot still inside. ARS scientists have received
approval for lab safety studies in the United States, as a prelude to
field tests in this country.
Medical
and Veterinary Entomology Research Laboratory, Gainesville, FL
Sanford Porter, (904) 374-5914
Honey bees are potential "couriers" for an environmentally friendly virus
that kills crop pests. A typical worker bee flies 500 miles and can
search thousands of flowers for pollen and nectar that she carries back to
the beehive. Scientists are recruiting female bees to drop off the virus
on plants. They have patented a device that fits on the bottom of a
standard beehive and dusts honeybees with a virus-talc powder mixture when
they exit. As the bees buzz from flower to flower, the nuclear
polyhedrosis virus and powder rub off their feet and legs and onto the
blossoms. The virus is harmless to honeybees, but killed from 74 to 87
percent of corn earworm larvae in crimson clover fields where the bees
carried the virus. That's compared to only 11 to 14 percent mortality in
fields where bees were not used. Crimson clover is an important host
plant for the first generation of corn earworms in early spring; later
generations then attack corn, cotton and other crops. This biocontrol
approach could be especially appealing to beekeepers who rent their bees
for pollinating crops. (PATENT 5,348,511)
Insect
Biology and Population Management Research Laboratory, Tifton, GA
John Hamm, (912) 387-2323
The codling moth, a pest of apple and pear trees, is the guinea pig in
ARS' first area-wide pilot project for integrated pest management
(IPM). Rather than pesticides, the project's main IPM weapon will be
a sex attractant that disrupts the codling moth's search for mates. Other
methods discovered by ARS researchers may join the IPM package, including
wasps released to attack the moth's offspring. Scientists at ARS and
cooperating universities want to see how well IPM works when applied
throughout a large area rather than on a single field or farm. Test sites
are in five commercial apple and pear growing areas in California, Oregon
and Washington. About 75 growers own the areas which range from 300 to
1100 acres. Earlier IPM studies have been on smaller plots. The project
supports USDA's goal of helping producers apply IPM on 75 percent of U.S.
crop acres by the year 2000.
Tree Fruit Research
Laboratory, Yakima, WA
Carrol Calkins, (509) 575-5945
A new, easy-to-use trap that catches both male and female Mediterranean
fruit flies is being tested in California and 12 countries. A blend
of chemical scents and colors lures flies inside a plastic cylinder, where
they die after gobbling up a mixture of methomyl insecticide and sugar.
The chemical scents, ammonia and putrescine, mimic the smell of decaying
fruit. The chemical blend can be fine-tuned to attract females before
they mate and lay eggs inside fruit. Current traps attract only males, or
contain liquid bait that is easy to spill in the field. ARS is seeking a
patent on the new dry-bait trap, and several companies have expressed
interest in developing it commercially. (PATENT APPLICATION
08/231,213)
Insect
Attractants Laboratory, Gainesville, FL
Robert R. Heath/Nancy D. Epsky, (904) 374-5735
Adding tiny amounts of fungicide to the fungus Gliocladium virens
could save this promising biocontrol agent from a harmful flaw when
applied in cotton fields. ARS scientists discovered G. virens
naturally produces antibiotics that help cotton seedlings fend off
disease-causing soil microorganisms. But G. virens also naturally
produces a steroid called viridiol that can harm cotton plant roots.
Laboratory tests showed that treating G. virens with minuscule
doses of fungicide stops the fungus' viridiol output without hindering its
antibiotic production. Next step: screening various G. virens
strains to find one with genes to make antibiotics, but minus the genes
for viridiol production. (PATENT 5,268,173)
Cotton Pathology Research, College Station, TX
Charles R. Howell, (409) 260-9233
Beneficial wasps have one of the highest success rates of all
biocontrols that protect U.S. crops. Two ARS experts on the wasp
superfamily, Chalcidoidea, are helping to develop a manual for
these wasps along with a group of specialists from Canada and England.
Several hundred pages of text and more than 1,500 illustrations help to
identify over 700 groups of potentially beneficial wasps--some of which
can be harmful. The key will help quarantine specialists at ports of
entry, insect-rearing companies and state and federal laboratories to make
a first-step identification to differentiate harmful from beneficial
wasps.
Systematic
Entomology Laboratory, Washington, DC
Eric Grissell/Mike Schauff, (202) 382-1781/1784
Eggplant farmers are lining up to get help from a beneficial wasp that
eats Colorado potato beetles. In field tests in New Jersey, the wasps
cut pesticide applications from 16 to two--a savings of $20 to $30 per
spray. The wasp, Edouum puttleri Grissell, lays its eggs in beetle
eggs. Any remaining eggs are stung. When young wasps hatch, they
parasitize and kill more beetle eggs. Fewer pesticide sprayings not only
save money and protect the environment, but make it safer for workers to
hand-harvest eggplants. ARS scientists worked with scientists at Rutgers
University, New Brunswick, NJ, and the New Jersey Department of
Agriculture. Local farmers are lining up to pay the small fee required to
get in the program. Ten farmers are participating in the program on 100
acres of eggplants.
Insect Biocontrol
Laboratory, Beltsville, MD
Bob Schroder, (301) 504-8369
Last updated: November 15, 1996
Return to: Quarterly Report
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