Fire Ants!. In the 1930s, the red imported fire ant was introduced to the United States at the port...
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Transcript of Fire Ants!. In the 1930s, the red imported fire ant was introduced to the United States at the port...
Fire Ants!
• In the 1930’s, the red imported fire ant was introduced to the United States at the port of Mobile, Alabama.
• Originating in South America, it is generally thought that they arrived through soil used as ballast in cargo ships.
Origin
The Current Port of Mobile, Alabama
South America Stow Away Ants
The RIFA – Solenopsis invicta
http://www.aphis.usda.gov/plant_health/plant_pest_info/fireants/downloads/fireant.pdf
© RWR
Photo credit: Alex Wild - myrmecos.com
10/2/2008
• The Animal and Plant Health Inspection Service (APHIS) hopes to inhibit further infestation by regulating the transport of certain items identified in the Federal Quarantine.
• Imported fire ants currently infest more than 320,000,000 acres across thirteen states and one territory (Puerto Rico).
• They are considered a pest because of their painful stings, aggressive behavior and affect on numerous agricultural products.
Demonstrating Infected Areas Under Quarantine
• Females have a shiny red head with a black back segment.
• Males are totally black• Size: 2.4 6 mm
General Characteristics
• A mature nest consists of one-quarter million workers.
• The sole purpose of a male ant is to mate; after which, they die.
• Sterile female workers and a fertile queen ant are the primary occupants of a nest.
• Omnivorous• The colony will survive as long as
the queen and a few worker ants survive, making them basically impossible to eradicate.
• The species' Latin name, invicta, means "invincible“, which is extremely appropriate considering our incapability to eradicate them.
• Red imported fire ants are the most aggressive of the imported ants, tending to swarm when disturbed.
Behavioral Tendencies
• They prefer to occupy areas where the temperature mean is 15°C or higher.
• The mounds are large, cone-shaped domes with hard, weather-resistant crusts.
• The average size for a mature mound is 10 inches to 24 inches in diameter and 6 inches to 18 inches tall. In heavy clay soil, the mounds may be much larger, sometimes reaching 3 feet in height.
• Such mounds may have galleries extending as far as 6 feet underground.
RIFA Mounds
Mating flights on sunny days 1-2 days after a rain when temperatures are above 75ºF
Flights usually occur in spring and fall but can occur at any time of year
Reproduction
Mating takes place 300 to 800 feet above the ground.
After mating, female seeks moist or reflective surfaces on which to land; male dies.
Female vulnerable to predators during and just after mating flight, especially other fire ants.
Reproduction
New colonies are founded by newly mated females (queens).
Once a queen lands, she removes her wings, burrows into the soil and begins to lay eggs.
Colony Formation
First batch of eggs grows up to be worker ants.
Worker ants are all sterile females capable of stinging.
Workers begin foraging and constructing mound.
eggs
Colony Formation
A queen can live 5-7 years and lay up to her own weight in eggs per day (800-3000 eggs).
eggs
Colony Formation
Worker immature and mature stages
Large workers live about 90-150 days as adults Small workers live about 60-90 days as adults Regardless of size, they change jobs as they age
nurse guard/excavator forager
Development
Mounds often are not clearly visible within first few months.
A small mound with several thousand ants may be visible within six months.
Mound Development
Fire ant mounds can be recognized by their dome or cone-shape. Mounds can be quite large (sometimes 60 cm tall and 60 cm wide). Mounds usually found in open areas. Unlike the nests of most other ants, fire ant mounds have no openings and little visible activity on the mound surface, unless disturbed.
Mound Development
Lateral foraging tunnelExit / Entrance
Lateral foraging tunnel
Deep tunnels to water source
Interconnectedchambers
If the mound is disturbed, the workers rush to save the queen and the immature ants.
Workers move the immature fire ants and the queen around the nest, for near constant temperature and humidity, often more than once per day.
The fire ant has 4 life stages
Eggs
PupaAdult
Larvae
Larvae molt four times over a 12-15 day period.
Larval Stages
Fourth instars are the only stage that can feed on solid food (black arrow points to food particle).
Fire ants eat a variety of foods
and are excellent foragers.
Reagan, LSU AgCenter
Food Sources
Trophallaxis
Foraging ants bring the food back to the nest.
The ants pass the food to one another by regurgitating it from their crops as liquid until food is distributed to all members of the colony, including the queen (trophallaxis).
Adults cannot digest solid food.
15-80 mounds per acre, 7 million ants per acre One queen per colony Worker ants are territorial The majority of fire ant colonies are of the single queen type
Single Queen Colony
Multiple Queen Colony
200-800 mounds per acre, 14 million ants per acre More than one queen in each colony Colonies reproduce by budding Worker ants are not territorial Typical form in Texas
Reproduction Type
• Single queen (monogyne)– territorial and aggressive– limited life to colony
• Multiple queens (polygyne)– non-territorial and not aggressive toward
each other – will adopt new queens– long-lived colonies
Economic Cost Of Fire Ants?• Estimated total between 1957 and 1984:
– $172 million• Stings:
– 1500 cases of severe allergic reactions/year– 2-5 deaths per year– $2.84 million per year to treat sting victims
• Crops:– $125 million/year to soybean growers alone– Total estimated economic impact annually: $6 billion
C. F. Lard et al., An Economic Impact of Imported Fire Ants in the UnitedStates of America (Texas A&M University, College Station, TX, 2006).
Cost Estimates
http://www.ars.usda.gov/fireant/impact.htm
Problems with RIFA
• Cause numerous environmental and medical problems
• Destruction to crops, damage to farm equipment, demise of newborn livestock
• Medical problems include large local reactions, secondary infections from the sting, anaphylactic reactions, neurological manifestations, and even death
Problems Created By Fire Ants• Public health
problems• Agricultural problems• Wildlife and the
environment• Miscellaneous bizarre
effects
• Attacking en masse, the ants respond to pheromones that are released by the first ant to attack.
• A fire ant typically bites with its mandibles, then swivels its abdomen and stings repeatedly in an arc about the bite site.
• When used against prey, it can kill or paralyze. When injected into humans, the toxic alkaloids produce an immediate burning sensation at the entry site.
• Their stings develop into sterile pustules and then rupture
“Fire Ants ATTACK!”
Fire Ant “Bites”
Fire AntBaits
Chemicals for Fire Ant Control
Biological Control
Predatory flies(Phoridae)
Phorid Fly Selecting a Victim
Fire Ant Decapitated by Phorid Fly
Sting
• Burning pain, both bite and sting • Attaches itself with its mandibles • Arches at the peduncle and inserts the stinger
– 0.007 to 0.11 µl of venom is injected– Skin Responses
Venom
• Young workers use venom during brood care as an antiseptic
• Older workers use it to capture victims• Defense against intruders • 95% water-insoluble 2,6-disubstituted piperidine
alkaloids • Alkaloid components are classified as either
solenopsins, isosolenopsins, or dehydrosolenopsins
Venom
• Classification depends on the enantiomeric configuration and alkyl or alkenyl carbon chain
• Alkyl chains have either 11, 13, or 15 carbons • Composition of alkaloids may be different
depending on the size and age of the worker or in a particular nest
Venom
• Contains 5% soluble proteins• Proteins are the active allergens • 5% aqueous portion contains four allergenic
protein components: – Sol i 1 (37 kD)– Sol i 2 (13.2 kD)– Sol i 3 (24 kD)– Sol i 4 (13.3 kD)
Venom Alkaloids
• Alters normal physiologic function in rats• Inhibit Na+-K+-ATPase pump (mammalian
muscle cell) • Induce platelet aggregation• Hemolytic activity
© RWR
S. invicta Venom Alkaloids
•Unique among stinging insects
– ~95% alkaloids and ~5% proteins
•Potential for alkaloid toxicity unknown
Venom contains mixture of several forms – isosolenopsins – solenopsins– dehydrosolenopsins)
Synthesis by National Center for Natural Products Research (Ole Miss)
NH
(CH2)nCH3
(2R,6R)-Solenopsin A(2R,6R)-Solenopsin B(2R,6R)-Solenopsin C
n=10n=12n=14
NH
(CH2)nCH3
(2R,6S)-Isosolenopsin A(2R,6R)-Isosolenopsin B(2R,6R)-Isosolenopsin C
n=10n=12n=14
NH
CH
CH
(CH2)7CH3(CH2)n
(2R,6R)-Dehydrosolenopsin B(2R,6R)-Dehydrosolenopsin C
n=3n=5
10/2/2008
Entomology Humor