II' a' Imported Fire Ant Introduction and Biology

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II. a. Imported Fire AntIntroduction and Biology
Teaching Module for Advanced Master Gardener
Training
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Where are imported fire ants from? Where are
they found in the US?
Need new map
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History of Imported Fire Ants

• 1918 estimated introductions occurred of black
  imported fire ant (Solenopsis richteri)
• First introduced in Mobile, Alabama
• Red imported fire ant (S. invicta) followed in
  the early 1930s
• The two species have hybridized
• Imported fire ants currently infest 330 million
  acres in the U.S.
• No natural enemies native to U.S.

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History

• IFA are the most destructive and costly ants in
  the U.S.
• IFA thrive in disturbed habitats, natural or
  man-made disturbances
• IFA continue to expand in the U.S. and their
  final range has yet to be reached

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Identification

• Habitat found in open, sunny areas
• Mounds large, no activity on surface
• Ants very aggressive when disturbed
• Stings painful, leave white pustule, sting more
  than once

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Pustules
Bite and Sting
Sting and Poison Gland

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Types of Adult Fire Ants
Winged female
Winged male
Workers
UC Statewide IPM Program
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Polymorphism in Worker Ants
major
queen
media
minor
Adult fire ant workers have different morphs
(polymorphic), i.e. major, media and minor, which
greatly vary in body size. Majors are often used
in identification because of their large size.
Not all ant species exhibit polymorphism.
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Fire Ant Anatomy Major Body Parts
AL
AL alitrunkAN antennaCE compound
eyeG gasterH headM mandibleMT mesothoraxP
petiolePP post-petiolePR propodeumPT
prothoraxS stingT teeth (mandibular)
PR
PP
H
MT
G
PT
AN
S
CE
P
M
T
Solenopsis
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Solenopsis invicta BurenImported Fire Ant Anatomy
USDA

• Reddish to brown in color
• Large eyes
• Workers are polymorphic (1/6 1/5
  in. long)
• Waist with 2 nodes
• No spine on propodeum
• 10 antennal segments
• 2-segmented antennal club
• Brown gaster with stinger
• Extremely aggressive

Photos by AntWeb
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Comparing RIFA to a Carpenter Ant
Common Black Carpenter Ant
Alex Wild 2003
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Relative Size of Ant Workers of Various Species
Texas Imported Fire Ant Research Management Plan
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Mating and Dispersal

• Mating flights occur on sunny days within 24
  hours of rain, when temperatures are above 75ºF.
  
• Flights usually occur in spring and fall, but may
  occur after any rainfall.

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Mating and Dispersal

• Mating takes place 300 to 800 feet above the
  ground.
• After mating, females seek moist or reflective
  surfaces on which to land male dies.
• Female is vulnerable to predators during and just
  after mating flight, especially to other fire
  ants.

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Colony Development

• 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.

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Colony Development

• The first batch of eggs grow up to be worker ants
• Takes 20 45 days for adult maturity
• Worker ants are all sterile females capable of
  stinging
• Workers begin foraging and constructing the mound

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A Queens Life
EGG

• After the first batch of workers is grown, the
  queen will always be tended by her workers.
• The queen can live 5-7 years and can lay eggs
  equal to her own body weight each day.

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Mound Development

• Mounds often not visible the first few months
• Within six months a small mound becomes visible
• May have 100,000 ants present

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Mound Development

• Mature mounds may be quite large
• - Distinctive trait
• Mature colonies may contain 200,000 to 400,000
  worker ants
• - Polymorphic colony population

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Mound Structure
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If the mound is disturbed

• Workers rush to save the queen and the immature
  ants

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Colony Life

• Workers move the young fire ants and the queen
  around the nest
• Often move more than once per day
• Maintains near constant temperature and humidity

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Fire Ant Life Stages
Egg

• Complete metamorphosis
• 4 life stages

Pupa
Adult
Larvae
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• Eggs found in brood chamber of a mound
• Eggs usually take 7-10 days to hatch

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Larval Instars

• Larvae molt four times over 12-15 day period
• First three instars fed regurgitated liquid food

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Black arrows point to a piece of solid food in
the food basket below the mouth

• Fourth instars are the only stage that can feed
  on solid food

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Fire Ant Diet
Fire ants eat a variety of foods
Pollet, LSU AgCenter
and are excellent foragers
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What do fire ants eat?

• Mostly other insects (predators)
• Tend aphids and scale insects for honeydew
• Plants and seeds that produce oils
• Fire ant workers DO NOT eat solid food
• Feed by trophallaxis

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Trophallaxis

• Foraging ants bring food back to the nest.
• Ants pass the food one to the other by
  regurgitating it from their crops.
• Adults pass liquid food around.
• Adults cannot digest solid food.
• Food is distributed to all members of the colony,
  including the queen.

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Fire Ant Development
Worker immature and mature stages

• Large workers live about 90-180 days as adults
• Medium workers live about 60-90 days as adults
• Small workers live about 30-60 days as adults
• Regardless of size, they change jobs as they age
• - nurse
• - guard/excavator
• - forager

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Development of Castes
Worker immature and mature stages
Egg
Queen
Reproductive immature and mature stages

• Pattern of development similar for worker and
  reproductive stages
• Males develop from unfertilized eggs
• Female reproductives get special food and hormones

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Two Types of Colonies

• Single queen (monogyne)
• - territorial and aggressive
• - limited life span of the colony
• Multiple queens (polygyne)
• - not territorial or aggressive toward each other
  
• - will adopt new queens
• - long-lived colonies

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Monogyne Queen Colony

• 15-80 mounds per acre
• Up to 7 million ants/acre
• One queen per colony
• Worker ants are territorial
• Found in all southeastern states in the U.S.

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Polygyne Queen Colony

• 200-800 mounds per acre
• Up to 14 million ants per acre
• More than one queen in each colony
• Colonies reproduce by budding
• Worker ants are not territorial
• Predominant form in Texas

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For More Informationhttp//www.extension.org/fi
reants
Publications, slide sets, streaming video,
posters, and more
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Acknowledgments

• Thanks to the Texas Imported Fire Ant Research
  Management Plan, Texas AM University System, for
  the use of many of the images seen in this
  presentation.
• Portions of this presentation were made possible
  by a grant from the Southern Region Sustainable
  Agriculture Research and Education Professional
  Development Program.
• Authors
• Kerry Smith Alabama Cooperative Extension
  System
• Molly Keck Texas AgriLife Extension Service
• Bart Drees Texas AgriLife Extension Service
• David Williams University of Florida
• Ken and Rufina Ward, Alabama AM University

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Acknowledgments

• Reviewers
• Dale Pollet Louisiana State University AgCenter
• Karen Vail, University of Tennessee
• Chazz Hesselein, Alabama Cooperative Extension
  System
• Kathy Flanders, Alabama Cooperative Extension
  System
• Editor, Technical Facilitator
• - Neal Lee