July 2013 Articles

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Insect Management - Red Imported Fire Ants - Environmental and Economic Impacts

Insect Management—Red Imported Fire Ants—Environmental and Economic Impacts ( Continued from November Issue) Red imported fire ants can have positive and negative impacts on the environment and the life in it. However, to most of the public, fire ants' impact can only be considered negative. Environmental-Positive Impact
As generalist feeders, they can have more than one food source, Insect Management—Red Imported Fire Ants—Environmental and Economic Impacts ( Continued from November Issue) Red imported fire ants can have positive and negative impacts on the environment and the life in it. However, to most of the public, fire ants' impact can only be considered negative. Environmental-Positive Impact
As generalist feeders, they can have more than one food source, and other insects are often their prey. Researchers have found that RIFA can be beneficial in sugarcane and cotton fields. The ants predate on many of the lepidopteran larva found in these agronomic situations. For example, in sugarcane RIFA are known to feed on sugarcane borer larva. Whereas in cotton they feed on several of the pests present there. Research in cotton has found that the presence of 4 fire ants per boll can have a positive impact on cotton. As ground dwellers these ants are also known to prey upon the susceptible stages of fleas and ticks. This is a positive note for cattlemen attempting to deal with RIFA. Negative Impact
However, due to their competitiveness, it has been noted that there are decreases in the diversity and number of other ant species once RIFA infests an area. They also been found to affect wildlife, especially ground nesting species such as rodents, bobwhites, and deer. Economic The economic impact of RIFA is a definite negative. However, the actual economic impact is difficult to define due to the vast areas and types of situations it impacts. The average homeowner can spend hundreds of dollars a year in control measures. For example, a survey conducted in Arkansas found that $265/ household was lost to fire ants. Urban homeowners (<1 acre of land) reported an average of $87.00 lost, while rural homeowners (>1 acre of land) reported losses of $298.00. Red Imported Fire Ants—Frequently Asked Questions I have seen advertisements about using nematodes to control fire ants -- does it work?? Yes, and no.... Studies conducted in Florida found 10-20% control can be obtained. The studies found that the when fire ant colonies (mounds) are treated with nematodes, the colonies simply move and abandon the treated mound. 10-20% control generally isn't sufficient for most people trying to control fire ants and thus it may not be worth the effort. Why do fire ants sting all at once if you have more than one ant stinging?? Fire ants have a complex system of communication in which they use numerous types of signals. The signals can be chemical, visual, & vibrational. Entomologists and chemical ecologists have found for example that when a fire ant dies it emits an death pheromone that causes live ants to pick it up and carry it out of the colony tunnels. There are recognition pheromones, and trail pheromones which are also used by fire ants. Trail pheromones are used by other ant's to locate food.
To date, entomologists haven't found out exactly what cue the ants use to sting "all at once", but they believe it is one of their communication signals. If you have the opportunity - check out the Spring 1997 issue of American Entomologist - a relly good science-based article about the red imported fire ant.
and other insects are often their prey. Researchers have found that RIFA can be beneficial in sugarcane and cotton fields. The ants predate on many of the lepidopteran larva found in these agronomic situations. For example, in sugarcane RIFA are known to feed on sugarcane borer larva. Whereas in cotton they feed on several of the pests present there. Research in cotton has found that the presence of 4 fire ants per boll can have a positive impact on cotton. As ground dwellers these ants are also known to prey upon the susceptible stages of fleas and ticks. This is a positive note for cattlemen attempting to deal with RIFA. Negative Impact
However, due to their competitiveness, it has been noted that there are decreases in the diversity and number of other ant species once RIFA infests an area. They also been found to affect wildlife, especially ground nesting species such as rodents, bobwhites, and deer. Economic The economic impact of RIFA is a definite negative. However, the actual economic impact is difficult to define due to the vast areas and types of situations it impacts. The average homeowner can spend hundreds of dollars a year in control measures. For example, a survey conducted in Arkansas found that $265/ household was lost to fire ants. Urban homeowners (<1 acre of land) reported an average of $87.00 lost, while rural homeowners (>1 acre of land) reported losses of $298.00. Red Imported Fire Ants—Frequently Asked Questions I have seen advertisements about using nematodes to control fire ants -- does it work?? Yes, and no.... Studies conducted in Florida found 10-20% control can be obtained. The studies found that the when fire ant colonies (mounds) are treated with nematodes, the colonies simply move and abandon the treated mound. 10-20% control generally isn't sufficient for most people trying to control fire ants and thus it may not be worth the effort. Why do fire ants sting all at once if you have more than one ant stinging?? Fire ants have a complex system of communication in which they use numerous types of signals. The signals can be chemical, visual, & vibrational. Entomologists and chemical ecologists have found for example that when a fire ant dies it emits an death pheromone that causes live ants to pick it up and carry it out of the colony tunnels. There are recognition pheromones, and trail pheromones which are also used by fire ants. Trail pheromones are used by other ant's to locate food.
To date, entomologists haven't found out exactly what cue the ants use to sting "all at once", but they believe it is one of their communication signals. If you have the opportunity - check out the Spring 1997 issue of American Entomologist - a relly good science-based article about the red imported fire ant.

I put out bait and it didn't work? There are several things you need to know about baits and they are as follows:
Baits are less effective in areas with abundant food sources, such as: dumpsters, chicken houses, pet's feeding dishes, trash cans, etc.
The bait used was stale -- once the container is opened the bait needs to be used within 6 months to 1 year --- if not it becomes stale and unattractive to the ants
Contact insecticide applied some time prior to treatment, suppressing foraging activity
Baits should be used around building foundations, driveways, curbs, sidewalks, and other areas in which contact insecticides cannot penetrate. (Placement of 1 Tablespoon (TBSP) per 15 feet is equivalent to 1 1/2 pounds broadcast.)
Baits are most effective when temperatures are above 70F. IF daytime temperatures are in the 90's a nighttime application may be more effective. IF temperatures are questionable, place a same amount of bait or other food (potato chips) close to a mound. Ants will start to carry off the food within 15 minutes if conditions are favorable.
Do not use baits on wet surfaces such as grass with dew. This will make the bait less desirable to the ants - remember the ants perceive the baits as a potential food source.
Broadcasting baits is normally more effective in reducing fire ant populations than mound treatments.
Broadcasting baits is more economical and less labor intensive than mound treatments in areas with more than 40 mounds per acre.
Although most baits control mainly big headed ants such as fire ants, mound treatments with baits is probably least damaging to the native ant populations since it is site specific and there will be no ants other than fire ants foraging near a fire ant mound.
Treatments using a broadcast bait application is discouraged in areas with less than 20 mounds /acre based on concerns for non-target ants. A retreatment threshold of 20-30 mounds /acre.
Will RIFA develop resistance to the bait? Resistance to the insecticides is not expected due to RIFA's long reproductive cycle. However, behavioral resistance, i.e. avoidance of bait-formulated products is a concern. Red Imported Fire Ants—Health Hazards RIFA are very aggressive toward anything that disturbs their mound, and unlike bees red imported fire ants can sting more than once. A typical reaction to the sting of RIFA is a burning and/or itching sensation. Development of a white sore or pustule often results. Individuals who have a reaction to the venom may suffer chest pains and nausea. There have been individuals who have gone into comas due to the body's reaction to the venom. In 1988, 32 deaths across the southeast were attributed to RIFA. Against its prey the venom immobilizes or kills RIFA insect prey. The alkaloid based venom causes neucrosis or deadening of the tissues. Source: University of Arkansas—Fire Ant articles will continue to run over the next couple of months.