RED IMPORTED FIRE ANT BIOLOGY AND CONTROL

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RED IMPORTED FIRE ANT BIOLOGY AND CONTROL

• James T. (JT) Vogt, Ph.D.

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TOPICS OF DISCUSSION

• Brief history of introduction and spread
• Basic biology
• Dos and Donts of control (how biology relates to
  control)
• Available products, cost considerations
• Tailoring control methods to particular situations

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FIRE ANT FACTS (introduction and spread)

• Scientific name Solenopsis invicta Buren
• Accidentally introduced into US in 1930s
• Stowaway in ship ballast, landed in Port of
  Mobile, AL
• Currently infests 250 million acres in US
• Is adapting to drier conditions in western areas
  of infestation

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SPREAD OF S. INVICTA

• Mating flights (wind)
• Flooding
• Vehicles
• Agricultural commodities
• Horticultural commodities

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CURRENT STATUS OF S. INVICTA (NATIONWIDE)
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IDENTIFICATION

• Workers are polymorphic, generally reddish-brown
• Mounds (generally) honeycombed inside

Courtesy TAMU
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IDENTIFICATION CONTD

• Characteristic stinging behavior

Courtesy Tx. Dept. Agric.
A pictorial key is available from Texas AM
University
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BASIC BIOLOGY

• Castes
• Reproduction
• Nest structure
• Foraging and diet

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FIRE ANT CASTES

• Workers--all female, young workers tend brood,
  older workers forage
• Female alates--large winged females
• Male alates--dark in color, small winged males
• Queen(s)--reproductive females

Photo by C. Barr
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FIRE ANT ALATES
Photo courtesy of TAMU
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FIRE ANT WORKERS
Photo courtesy of S.D. Porter, USDA-ARS
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FIRE ANT REPRODUCTION

• MONOGYNE
• Single queen colonies
• Reproduce via mating flights

• POLYGYNE
• Multiple queen colonies
• Reproduce via mating flights
• Reproduce via budding

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THE MOUND (GENERAL)

• Fire ant colonies do not always build
  easily-detectable mounds
• Foraging tunnels radiate out from the mound, 2-8
  cm below the soil surface
• The soil of the mound warms and dries faster than
  surrounding soil
• Colonies are located in different parts of the
  mound during different times of the day
• Mound shape and ease of detection change
  seasonally

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NEST STRUCTURE
Photo courtesy of Texas Ag. Ext. Servc.
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FIRE ANT MOUND WITH TYPICAL HONEYCOMBED INTERIOR
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FIRE ANT COLONY HIDDEN IN LEAF LITTER
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FIRE ANT COLONY IN SIDEWALK
Photo by B. Drees
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FIRE ANT COLONY IN JUNCTION BOX
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FORAGING AND DIET (GENERAL)

• Common names for Solenopsis spp. Lard ants,
  grease ants (they are attracted to greasy foods)
• Forage year-round, whenever soil temperatures are
  favorable
• Optimal temp. (2 cm depth) for maximum foraging
  lies between 70 and 90F

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DIETARY HABITS

• Small arthropods, bits of larger arthropods and
  dead animals
• A few seeds
• Liquid food sources (nectaries, homopteran
  honeydew, etc.)

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FIRE ANT FORAGERS
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THE DOS AND DONTS OF FIRE ANT CONTROL

• (Or, how fire ant biology relates to control
  methods and decisions)

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2 WAYS TO TREAT FIRE ANTS

• INDIVIDUAL MOUND TREATMENTS
• Labor intensive
• Rapid control if contact insecticides used
• Difficult to find all mounds
• Temperature-dependent

• BROADCAST BAITS
• Ca. 80-90 effective
• Control is slow (2-8 weeks depending on product)
• Controls small, hard to detect colonies
• Can treat large areas
• Temperature-dependent

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INDIVIDUAL MOUND TREATMENTS

• Dusts, granules, pre-measured drenches,
  injectible aerosols
• Good if rapid control of a few mounds is required
• Baits can be used on single mounds but control is
  slower

Courtesy Tex. Ag. Exp. Sta.
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BROADCASTING BAITS

• You should use a seed spreader to broadcast baits
  
• Cannot mix baits with fertilizer or other
  products
• Best for large areas that dont require immediate
  control

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DISTURBING THE MOUND

• Dont disturb mounds prior to any sort of
  treatment. This will alert the ants to danger,
  and will decrease the likelihood of hitting the
  queen and most workers with contact insecticides.

• Do take care to apply dusts, granules, and
  drenches very gently. This will insure contact
  with the greatest number of ants--and when
  baiting, will not distract ants from their
  foraging activity

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READING THE LABEL

• Dont apply products without carefully reading
  label instructions. Many products have
  specialized instructions that should be followed
  for best results.

• Do consult the label of the product you choose
  and check for info on timing of application,
  whether product requires watering in, etc.

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BAITING INDIVIDUAL COLONIES

• Dont apply baits directly to the tops of mounds.
  This will increase the time it takes for the
  ants to discover and retrieve the bait and
  increase the chances of photodegradation.

• Do apply bait products in a circular fashion
  around individual mounds, approximately 2-3 feet
  from the mounds base.

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FIRE ANTS IN ELECTRICAL EQUIPMENT

• Dont treat fire ant colonies in electrical
  equipment unless youre a qualified, licensed
  PCO. Check product label for specific
  applications!

• Do use materials specifically formulated for fire
  ants in electrical and utility housings. These
  include High Tech Insectape Insecticidal
  Strips, JS-685 , and Rainbow Fire Ant Killer.

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TEMPERATURE AND MOUND TREATMENTS

• Dont treat individual mounds when it is very hot
  or very cold outside. The colony will be far
  underground, lessening the chances of contacting
  all ants.

• Do treat individual mounds on warm, sunny
  mornings that follow cool nights. The colony
  will be located near the top of the mound, where
  insecticides will have a better chance of
  contacting ants.

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TEMPERATURE AND BAIT BROADCASTING

• Dont broadcast baits when it is too cold or too
  hot. Early season applications may not be
  effective--wait until late May-early June in
  Oklahoma.

• Do broadcast baits when soil temperature at 2 cm
  is approximately 80F (between 70 and 90F) after
  monitoring for activity.

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RAIN AFFECTS BAITING

• Dont apply bait products right before or right
  after a rain. Generally, if rain is expected
  within 24 h or has occurred in the last 24 h,
  postpone baiting programs.

• Do apply bait products when the ground is
  relatively dry. If applying in the morning, be
  sure that dew is not present on the grass.

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GIVE BAITS TIME TO WORK

• Dont be impatient! Hydramethylnon formulations
  will take 2 weeks or more to work, and IGRs will
  take up to 6 or even 8 weeks. Further
  application within this time interval is wasting
  !

• Do give the foraging ants plenty of time to
  retrieve and distribute baits. Avoid disturbance
  of colonies for at least 3 days after baiting,
  then treat problem mounds individually.

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USE FRESH PRODUCTS

• Dont use bait formulations that were opened more
  than several months ago, or have been stored in a
  hot area or left open.

• Do use fresh products whenever possible. Shake
  bait containers well before opening / using the
  product. Soybean oil attractants in baits can go
  rancid and can settle in stored containers.

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PRODUCTS AVAILABLE FOR FIRE ANT CONTROL
Mention of any product does not constitute
endorsement by Oklahoma State University,
Oklahoma Cooperative Extension Service, or
Oklahoma Department of Agriculture. The lists
presented here are not inclusive and may change.
Availability and registration of products may
change.
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BAIT FORMULATIONS
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INDIVIDUAL MOUND TREATMENTS
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COST CONSIDERATIONS

• Cost of product
• Baits per area basis or per mound basis
• 9-15 / acre, 0.50-0.90 / mound
• Drenches, etc. per mound basis
• 0.15-0.25 / mound
• Effort involved in application
• generally greater with indiv. mound trt.
• Time involved in application
• generally greater with indiv. mound trt.

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PLANNING CONTROL EFFORTS TO MEET PARTICULAR NEEDS

• No-tolerance areas
• nursing homes, mental health facilities, etc.
• Bait 2X / year, inspect monthly and drench any
  visible mounds. Encourage client to make
  improvements in structure, sanitation, etc., as
  necessary.
• Low-tolerance areas
• large green areas assoc. with businesses, etc.
• Bait 1 or 2X / year, inspect periodically.

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PLANNING CONTROL EFFORTS TO MEET PARTICULAR NEEDS

• Small lawns
• Bait 1 or 2X / year, drench problem mounds as
  they appear, or combination of both.
• Indoor infestations
• Immediately address the threat indoors (treat
  with a contact insecticide).
• Carefully inspect for mounds outside of
  structure, in wall voids, etc., and treat.

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WHERE TO BAIT?

• Researchers have shown that in order to eliminate
  fire ant foraging in areas next to polygyne
  infestations, a 40 m fire ant-free border is
  recommended!
• In NO TOLERANCE situations, it may be desirable
  to apply baits in areas bordering the property
  under contract--also in other situations, to
  reduce callbacks.

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TIPS FOR BAITING NEAR STRUCTURES

• Do not just place bait along exterior walls
• Never use outdoor baits inside structures
• Be sure to apply at appropriate temperatures!
• If necessary, treat border areas to slow
  re-infestation.

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TIPS FOR INSPECTING

• If you can, time inspections for 2-3 days
  following a good rain. New mound construction
  can be very visible during warm periods following
  rain.
• Pay particular attention to curbsides, sidewalk
  edges, and structures, especially where the
  grounds are frequently mown.
• Placing an attractive substance out and observing
  the foraging trail can tip you off on mound
  location.

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SUMMARY

• Knowledge of fire ant biology is essential for
  successful control programs.
• The two primary means of controlling fire ants
  (baiting and mound treatments) involve different
  costs and benefits, and can be integrated into a
  control program
• Tailoring your control program to the specific
  needs of the client is essential