Agricultural research

26 Pages·1994·3.2 MB·English

by  United States. Science and Education Administration

Archive Document
Historic,
Do assume
not content reflects current
scientific knowledge, policies, or practices.

— — — ——
.
FORUM
Solving Problems, Three non-USDA agencies and de- • perfect biocontrol methods and ge-
partments we serve are the Environ- netically resistant strains to reduce
Meeting Needs
mental Protection Agency, Food and losses from agriculturally important
The Agricultural Research Service Drug Administration, and Department pests and diseases.
is often called on to help solve urgent ofDefense. Range and forage management
problems beyond the regular routine of ARS can't solve every problem it's • develop low-input forage production
its everyday research. asked to solve, so agency program techniques and varieties;
A recent example is the team of planners review them and choose • improve rangeland management
ARS scientists helping combat a fire which ones to tackle based on whether methods to enhance the quantity and
ant population explosion in a remote the problem is researchable, solutions quality of water supplies;
Brazilian town (page 4). In this case, might already exist from previous re- • devise economically sound livestock
the short-term lending ofARS scientif- search, ARS is capable ofperforming foraging systems to help keep highly
ic expertise, coupled with corporate the requested research, resources to erodible lands under protective cover;
donation ofan appropriate technology, support the work are available, and • evaluate effects ofgrazing systems
may be all that is needed to bring relief solving the problem is compatible with on soil, hydrology, and productivity.
to a beleaguered community. the ARS mission. That we are able to Animal health
This is technology transfer on a hu- shift expertise and resources to address • develop vaccines for avian influenza
man scale. ARS response to such ex- these special problems is due to our and brucellosis;
ternal requests for aid has been as gen- broad-based fundamental research pro- • improve diagnosis ofavian influenza,
erous and consistent through the years gram and flexible planning. bluetongue and other orbi\ iruses. bo-
as resources have allowed. This is part Current ARS research programs vine lentivirus, scrapie in sheep and
ofwhat the "s—ervice" in our agency's dealing with needs ofaction and regu- goats, and other diseases ofeconomic
name implies seeing to it that practi- latory agencies include: importance to producers.
cal applications ofour research emerge Food safety and nutrition Commodity quality enhancement
from the laboratory and fmd their way • identify multiple residues in food an- • detect and quantify mycotoxins and
to a wide range ofusers. imal tissues; chemical residues in stored grain:
Ofcourse, responding to one partic- • reduce foodbome bacteria, viruses; • refine rapid, objective classification
ular group ofextra-agency research • show the temperature to which a methods for wheat;
need—s is more thanjust good-hearted- product has been cooked or whether • create a biochemical test for insect
ness it's a mandate: One ofthe major it has been irradiated; parts in whole grains;
parts ofthe ARS mission is to carry • improve control ofcontaminating in- • devise a simple way to quantify
out research that supports action and sects and parasites; starch and fiber in feed grains;
regulatory agencies charged with en- • refme methods to assess the nutri- • design an automated grain inspection
forcing federal regulations and laws. tional status ofindividuals; system;
Currently, these include nine USDA • detemiine and enhance nutrient bio- • fine-tune instruments to measure cot-
agencies: the Agricultural Marketing availability; ton fiber qualit\ quickh^ and accu-
Service, Agricultural Stabilization and • identify nutritional components that rately, grade for objective evaluation
Conservation Service, Animal and reduce the risk ofcancer, diabetes, of meat animal cai'casses. and nonde-
Plant Health Inspection Service, Fed- obesity, and other chronic disorders. structively assess the ripeness of fresh
eral Grain Inspection Service, Food Pesticides and thie environment fruit
and Nutrition Service, Food Safety and • control aquatic and other serious
Inspection Service, Forest Service, Hu- weeds with integrated pest manage- Jesse W. Goble
man Nutrition Information Service, ment; ARS Budget and Program
and the Soil Conservation Service. • minimize applications that harni Management Staff
beneficial species;
The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color,
national origin, sex. religion, age. disability, political beliefs, and marital or familial status. (Not all prohibited bases apply to all
programs.)Personswithdisabilitieswhorequirealternativemeans forcommunicationofprograminformation(Braille, largeprint,
audiotape, etc.) should contact the USDA Office ofCommunications at [phone] (voice) or [phone] (TDD).
To file a complaint, write the Secretaiy ofAgriculture, U.S. Department ofAgriculture. Washington. DC 20250, orcall (202)
720-7327 (voice) or (202 720-1 127 (TDD). USDA is an equal employment opportunity employer.
2 Agricultural Research/January 1994
1
Agricultural Research
Cover: Imported redfire ants scurry across aPopsicle stick afterbeing disturbed by
scientists atARS' Medical andVeterinary Entomology Research Laboratory in
Gainesville, Florida. Widely disliked fortheir venomous, painful stings,fire ants have
spreadacross much ofthe southern United States. Photo by Scott Bauer. (K-5388-1)
4 Fighting the Fire Ant
ARS specialists aid a hapless town in the Amazonian rain forest.
10 Oat Chromosomes on Display
—
Video camera teams with computer to show all 21 pairs and in color.
f 11 Detecting Poultry Drug Residues
', '-3:.
Page 13 Monoclonal antibody probes speed tests for common coccidiostats.
12 Jumping Genes Make Genetic Leaps
One of these, corn's glossy-15, could lead to speedier crop maturation.
15 It's Over for Clover When Gnat Larvae Strike
Dark-winged fungus gnats can decimate stands in almost no time.
—
16 Super Slurper Two Decades and Still Growing
Agricultural uses for this starch-based absorptive may surpass use in
personal care products.
18 Breaking Up Is Hard To Do
Page 15
Impenetrable fragipan soils cause production and erosion problems.
20 Pheromone Monitoring Tracks Borers
Traps alert growers to the presence of mint and sugar beet pests.
21 Powerful Promoter Speeds Genetic Engineering Tests
Ubiquitin-1 has been shown to boost the effectiveness of marker genes.
22 New Seed Separator Gets the Goatgrass Out
Device fits on seed-cleaning machines already in commercial use.
23 Science Update
Page 18
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Agricultural Research/January 1994 3
—
Fighting tlie Fire Ant
Brazilian trip shows persistence of pest now found across the U.S. South.
HOMERCOLLINS/APHIS
ounds like somethingoutofan
old-time science fiction movie:
Millions ofaggressive,
stinging ants overrun a small city in
the Amazonrain forest, invading
homes, schools, churches, and stores.
Nothing seems to stopthem.
Butto thepeople ofEnvira, Brazil,
it's notamovie script. It's real Ufe.
There, in the Amazonrain forest,
the 10,000people whocallthis small,
riverbanktownhome havebeen
struggling against aboomingpopula-
tionoffire ants. It started several years
ago, when people noticed more and
more ofthe tiny, reddish-brown,
omnivorous insects foraging forfood.
Unable to stop them, the Brazilian
government askedforhelpfromfrre
ant experts in the U.S. Departmentof
Agriculture.
hi September 1993, three USDA
—
researchers entomologistDavid
Williams and agricultural engineer
Danel Haile oftheAgricultural
Research Service, andentomologist
HomerCollins ofthe Animal and
Plant Health Inspection Service
—
(APHIS) wenttoEnvira, armed with
2,000pounds ofbaitcontaining an
insect growthregulatorthat inhibits the
developmentofworkerfire ants. The
bait, calledLogic, was donated by the
chemical manufacturerCiba-Geigy.
The scientists went not only to help
the authorities control the pest, but also
to try to determine why fne ants Unnaturalimbalance: ClearedlandintheAmazonrainforestoutsideEnvira,Brazil,created
which now al—so infestthe southern adenviedleoalpmeennvtirmoanymebnetofnoerffiarcetoarntisn,fwihreicahnttphroipvuelawthieonnehxapbliotsaitosnsa.redisturbed.Scientistssay
United States hadtaken holdto such
an extentinEnvira, an otherwise as blanket coverage inside Brazil. "Almostevery familyhashad
typical town in the tropics. According to one report in the children attacked." the town's Mayor.
"It's notanexaggerationto say that Washington Post, the ants have Luiz Castro, was quoted as saying. If
the ants were overrunning the place," attacked vegetables, animals, and theproblemcannotbe solved. "Many
says Williams, echoing a sentiment people and have killed chickens, people are saying they will sell their
shared by Haile andCoUins. "We ducks, and turtles. Several children things andgo.... They are discouraged.
foundsomecolonies withmorethana were hospitalized after suffering Yourchildren can'tgo out andplay.
million ants inside. I'vebeen studying severe reactions to fire ant stings. You can't grow chickens. Myson
frre ants for 17 years, andI've never Like bee venom, the ant venom even hadbites inhis ears."
seen anything likeit." contains proteins that can cause The three scientists ha\e seen
The town'splighthas drawn anaphylactic shock and, in extreme serious fire ant infestationsbefore, in
international media attention, as well cases, even death. the United States. Williams, the team
4 Agricultural Research/Januar} 1994
realizedthen the extent ofthe prob-
—
lem how seriously they \'iewedit."
The nextday. the scientists began
looking forfire ant mounds, andit
didn'ttake long before they found
—
some. There werethousands andin a
dr\' ri\'erbed thatruns through the
town, they foundthe largest ones.
"We foundsomemounds there that
were about the size ofmy desk."
Williams says. "Ttwas a sight to see.
There wereeasilymorethan amilhon
ants in each one. They were thebiggest
fire ant colonies I've everseen."
On September 13, atatown meet-
ing, dozens ofpeople came forwardto
askquestions. "We reassuredthemthat
the insect growthregulatoris safe to
We
people andUvestock. also ex-
plainedhow it works andhow long it
would take to control the ants,"
Williams says.
Theybegan spreadingLogic, a
granularmaterial, on as much ofthe
2.400-acretownas they couldwith a
—
tractor andhand spreaders in areas
where the tractorcould notbe used.
"The ideal way wouldhave beenby
airplane, butthe areawas soremote
that it wouldn'thave beenpractical."
Haile says. "'Andit wouldhave been
too expensive thatway."
They spread about 500 pounds of
Logic andtreated individual fire ant
mounds. Logic contains the active
ingredientfenoxycarb. which inhibits
development ofworkerfire ants. The
chemicalis dissolvedin soybean oil
that is then appliedto com granules.
leader, is an entomologist at the ARS control and quarantine projects in the Fi—re ant workers carr>' the gran-
Medical andVeterinary Entomology United States. The Gainesville and ules about—the sizeofagrain of
ResearchLaboratory' in Gainesville, Gulfport sites are USDA's only fire ant coarse sand backto theirnest and
Rorida. He"s studiedthe ant extensive- research stations. feedthemtothe queen. She continues
lyinthe United States and in its native Despite theirexperience with the to lay eggs, butthey neverdevelop into
SouthAmerica. Haile. an agricultural pest, they weren'tpreparedforwhat workerants. Evenmally, workers that
engineer, is also based at the Gaines- they saw in En\rra when they landed at are present die and are notreplaced.
ville lab andprovided expertise inbait the small airstrip on September 10. Without workers, the queen also dies
appUcationtechnologies. ColUns. an ''No soonerhadwe steppedoffthe andthe colony collapses.
entomologist, is located at the APHIS plane than we were—surroundedby Williams says the remaining 1.500
Imported Fire Ant Station in Gulfport. about 8,000people almostthe town's pounds ofchemical will be used for
Mississippi, and has worked on fire ant entire popularion," WilUams says. "We additionaltreatments duringthe rainy
Agricultural Research/Januar\' 1994 5
—
DANHAILE/ARS
seasoninFebruary 1994and again SOquickly andcan out-compete other
lateras needed. The USDA teamhas ants that are less aggressive stingers ."
trained Brazihan scientists to make They also have the ability, unique
those applications, andthe Brazilian among ants, to float on water.
researchers will teach Enviracitizens to Envirais located alongtwo tributar-
treat individual ant mounds. Without ies ofthe Amazon, andduring the wet
these efforts, the ants will return. season, therivers flood. Rising water
drowns many ants, butfire—antworkers
Where'd They All Come From? formthemselves into aball the size
How were the ants able totake over ofa Softball oreven a soccerball
aroundthe queentoprotecther. Asthe
Envira?Theresearchers say there are
severalkeyreasons. waterrises, they float on top ofit like a
One was the rapidgrowth inthe area boat, WiUiams says.
"Whentheybump into something,
overthe lastdecade. Between 1980 and
1993, the town'spopulationmush- they climb onto it," he says. "Ifthat
something happens tobe ahouse,
roomedfromanestimated 1,000to
10,000. As the city expanded, more they'll nest inthe house. Forfire ants,
landwas clearedfornew housing, floods aren't adangerbut are simply a Totherescue: USDAresearchersreceiveda
streets, andotherconstruction. As the way forthemto move around." lotofattentionwhentheylandedina
The researchers also saythat, based BrazilianAirForcecargoplaneatthe
native forest andhabitatwere de- on whatthey weretoldbylocal En\iraairstrip.
stroyed, the fire antpopulation grew.
authorities, fire antpopulations began because they're pretty wellprotected
"Fire ants thrive wheneverthe
toboom several years ago whenthe deep inside."
native habitatis disturbed," Williams government stopped spraying DDT to WiUiams saidthey were unable to
says. "That'sbecause they reproduce
control malaria-causing mosquitoes. confirmmultiple-queencolonies
Also, until recenfly, trash wasn't
—
SCOTT BAUER properlydisposedof providing a DANHAILBARS
ready food supply forthe ants, which
will eatjustaboutanything.
"Withallthosefactors atwork, it's
nothardto see why the antpopulation
tookoff," WiUiams says.
Buttheresearcherscouldnot
conclusively determine akey biologi-
cal factor: whetherthe mounds in
Enviracontainedmultiple queen
colonies. Fire antnests usually contain
only one queen, whichcanproduce her
— —
weight in eggs about 2.000 every
24hours, WiUiams says. But, overthe
last decade, researchers have discov-
eredcolonies where workers—will
acceptmore than one queen meaning
muchhigherant populations.
"We'repretty sure that the larger
colonies, withmorethan 500,000 ants,
had multiple queens," he says. "Idug
Smallbutfeisty: Similartothefireantsin into one andfound aqueen right away. Ouch!Multiplefireantstingscausedthe
Brazil,thislaboratorycolonyofred Normally you'dhave ahardtime soresonthisyoungresident'slegandfoot.
importedfireantsgetsacloseinspection
fromentomologistDavidWilliams(left)and findingthe queeniftherewas only one.
agriculturalengineerDanHaile.(K5386-15)
6 Agricultural Research/Januaiy 1994
have similartrouble. "Othertowns
may have aproblembuthaven't
reportedit, since many ofthem are so
remote." Williams says.
The researchers have notyetmade
plans toretumtoEnvira, butwould
liketogobacktolearnmore aboutthe
fire antinfestation there andto see if
thebaitapphcations have worked.
Once theinitial supply ofbaitis used
up, Enviraofficials say, they don't
have money to buy more.
"One thing is clear: Ifthe BraziUans
don'tcontinue to treat, the fire ants will
be back," Williams says.
Fighting the Fire Ant at Home
There arenoEnvira's inthe United
States when itcomes to frre ants. But
thepests have causedtheirshare of
troublehere sincethey were acciden-
psrtiumdayrtihlyemb.ec"Iatusweasithwaarsdstooddioffmiucuclthto whyWhEantvitrhaehsacidenstuicsthsadnono'vtekrwnhoewhnising tally imported from South America
more than 50years ago.
poking around inthe antmounds,"he fire antpopulation, while othercities in
acknowledges. "I was stung 50, maybe the Amazonbasin apparently don't
75 times inthecourseofprobing about
five orsix ant mounds. I wasjumping HOMERCOLLINS/APHIS
aroundquite abit."
"When I wouldpoke amoundwith
a shovel, ants wouldcome up from
inside tiny tunnels thatcan extend 50,
perhaps 100feet outfrom larger
colonies," he adds. "They're more
aggressive than the frre ants we know
in the United States. Within afew
seconds ofpoking anest, the ants come
rightout ofthe tunnels underyourfeet
andstartattacking. You haveno time
toreact."
Basedonpreliminary studies, the re-
searchers believe the frre ant species in
EnviraisSolenopsissaevissima, com-
monly found in South America, and a
sisterspecies ofS. invicta that infests
much ofthe southernUnited States,
fromTexas to Florida and as farnorth
asTennessee andNorfolk, Virginia.
Cooperating scientists are conduct- Home—base: ARSscientist—sDavidWilliams(left) andDanHaile found a hugemoundof
earth about 10feetlong occupiedbyagiantcolonyoffireantsinadry riverbedleading
ingfiirthergeneticteststoconfirm that intotheTarauacaRiverinbackground.Duringthewetseason,floodsdrivesomeants
the species fromEnvirais indeedS. upwardandclosertopeople'shomes,whileothersfloatdownstreaminbuoyant,livingballs.
saevissima.
Agricultural Research/January 1994 7
HOMERCOLLINS/APHIS
They now infest 11 southern states Patterson andARS entomologist
and PuertoRico, andthey have been Juan Briano atthe agency's South
found in, buteradicatedfrom, several American Biological Laboratory in
western states. Hurlingham, Argentina, conducted a4-
Like otherforeign invaders that yearfield study there from 1989 to
enterthe United States, importedfire 1993 using T. solenopsis againstthe
antshave thrivedhere in the absenceof fire ant species Solenopsis richteri.
natural enemies andas development The result: 85 to 90percentofthe
has disturbedthe habitats ofcompeti- colonies died afterbeing infectedwith
tive native ants. the biocontrol protozoan. And surviv-
EradicatingthemfromtheUnited ingcolonies were weakenedand
States is unlikely because they are so reducedto sizes 70to 80percent
widespread, butthey can be managed smallerthan normal, Patterson says.
so they aren'tas much ofaproblem, T. solenopsis'biocontrol potential
U.S. DepartmentofAgriculture was boostedlate in 1993 when Briano,
scientists say. in lab tests in Argentina, was ableto
RichardPatterson heads the fire ant infectS. richterifire antsbyfeeding
research unit them the organism directly. "Previous-
atGainesville. SCOTT BAUER ly, we thoughtthe ants couldonlybe
He says infected indirectly through whatwe
scientists call an intermediate host," Patterson
there are says. "Ifthathadbeenthecase, it
studyingthe wouldhave made itmuch more
basic biology complicatedto usetheorganismas a
andbehavior biocontrol agent."
ofthe ants and Patterson says theprotozoancanbe
are working transmittedeitherthr—oughfoodorfrom
on chemical thequeentohereggs makingits Wheretractorscouldn'tgo: Workers
repellants, potential even greater. "Ifwe can infect appliedLogic,aninsectgrowthregulator,
baits, and the queen, thenaU ofheroffspringwill withhand-heldsprayersinthedryriverbed.
biological be infected," he says. "Thatmakes
control control even more effective." them. Several majorchemical compa-
organisms. Furtherstudies arebeing undertaken nies are also interestedin setting up
Biocontrol to determine that T. solenopsis will kill formal cooperative research and
involves find- the fire ant speciesS. invicta, the developments agreements tocommer-
ing natural en- problemant in the United States. S. cialize these repellants.
emies in the invicta andS. richteri are related In otherworkonrepellants. "a
ants' native Fireantsfeedon species, andPatterson expects the patentappUcation hasbeen submitted
South Ameri- laboratoryration. protozoan to be effective againstboth. covering several chemical classes of
caandbring- (K5387-14) Scientists areplanning additionallab repellants," says RobertK. Vander
ingthemback studies in 1994 andfield smdies in Meer, achemist atthe Gaines\"ille lab.
to this coun- 1995, before seeking regulatory "We alsohave formalresearch and
try. Oneofthemostpromisingcandi- approvaltouse T. solenopsis inthe development agreements withindustry
dates is Thelohania solenopsis. United States. aimed atdevising slow-release formu-
Itis atype ofprotozoan, called a In otherfire antresearch underway lations oftherepellants. So far, we've
microsporidian, thatresearchers atGainesville: beenabletoextendtheeffective
discoveredin South Americainthe •Wilhams has evaluated 33 repellantlife to 6 months."
1960's. Its spores infectfire antfat and chemicals as fire antrepellants and Currently available fire antbait
bloodcells, eventually weakeningthe found severalthatlookpromising. toxicantsharm nontargetant species,
ants andkillingthecolonies. Scientists can'tgive specifics yet, making iteasierforfire ants toreinfest
because ARS plans to seekpatents on an area. "We are de\elopingphero-
8 AgriculturalResearch/Januan 1994