Who's in Control?
Beyond the fact that your customers want to get rid of them, what do you know about red imported fire ants (RIFA) and the options in controlling them? RIFA brought an interesting history with them to the United States, along with a reputation for being a health hazard and dangerous pest.
The red imported fire ant, Solenopsis invicta, established around Mobile, Ala., in the 1930s, and probably arrived via soil from South America used as ship ballast. They have spread relentlessly in every direction during the last 70 years. The map in Chart 1, page 27, shows their anticipated range in the United States. As a grounds maintenance professional, you may have a potentially life-threatening insect infesting the property for which you are responsible. A small percentage of the population is so allergic to fire ants that two or three stings can cause anaphylactic shock and, ultimately, death. Damage to electrical equipment by fire ants also is a fact of life in the South.
If there was one fire ant control product that was best for every situation, this would be a very short article … and I would be out of a job. Unfortunately, no single product offers all the best control characteristics. Consequently, effective, affordable fire ant control is best done through what I like to call the “targeted treatment” approach: Treat only where you need to treat, using the least-expensive, most-effective product.
What is the best treatment? Ask yourself what your goal is. Do you want them gone fast? Do you want them gone for a long time? How much can you afford? Product selection is a balancing act based on your control needs. There are three basic characteristics of concern: speed of control, duration of control and cost. To note, here's a simple fact of life in fire ant country: No product will give 100 percent control every time or last more than about a year.
SPEED OF CONTROL
If the head coach storms into your office on Aug. 25 and rants about fire ants on the football field for that Sept. 1 game, speed of control is your goal. Until last year, there wasn't much you could do for that coach. The fastest products, those containing hydramethylnon, took three to six weeks to fully control colonies. In 2004, however, DuPont Professional Products introduced a broadcast bait containing Indoxacarb (DuPont Advion fire ant bait). It is used just like any other bait and reliably gives more than 90 percent control in three days, and close to 100 percent in a week, at a cost of about $15 per acre. Other than surface-sprayed contact insecticides, no other product comes close to that speed.
DURATION OF CONTROL
With most other insecticides, the term “residual control” is used for the period in which a chemical residue will continue to kill insects after application. However, none of the fire ant bait products have any chemical residual control. Reappearance of fire ants in a treated area is due to natural reinvasion by either mating flights or ground migration. The rate of reinvasion depends on season, weather and a host of other factors, but it will generally happen in less than a year. Consequently, the term “duration of control” is more appropriate than “residual control.”
Granular fipronil (TopChoice) is applied as a broadcast granule and takes about a month to work; however, it provides an extremely long, true residual. Some tests show more than 90 percent control maintained for over a year, and sometimes longer. The cost: $245 per acre.
Broadcast-applied contact insecticides still are used widely by many professionals. Their main advantage over baits was speed, but that is less of an issue with the advent of Advion. Bifenthrin, for example, can provide residual control for several months. The problem with these treatments is they use several times the amount of pesticide per unit area as baits, and are indiscriminate killers of non-target organisms. Costs range from about $50 to $100 per acre.
Following the previous mentions of cost for various products, consider that labor differences on a per-application basis are minor because all the products are applied similarly; however, you must look at your year-long fire ant control program before deciding on a product. Fipronil granules cost more, but you will need only one application per year. How does this compare to your labor and product costs for two or three applications of other products?
Let's say it takes a worker 5 minutes to treat an acre with a vehicle-mounted spreader. Labor and machine costs are $30 an hour, so that's $2.50 per acre. Using fipronil then costs $245 + $2.50, for a total of $247.50 per acre.
Bifenthrin costs $100 per acre, but you need at least two, possibly three, applications per year: ($100 × 2) + ($2.50 × 2), equaling $205 per acre. This is less than fipronil, but you've used several times the amount of active ingredient; and what if you need a third application?
Even without doing the math, baits will come in at a fraction of the cost, but what if there is reinvasion between treatments and a stinging incident occurs? These are the kinds of choices you have to make in choosing fire ant control.
Broadcast products (primarily baits) are the most economical way to control fire ants from a commercial grounds-maintenance standpoint. The main reason? Time. It takes one person approximately 15 minutes to treat an acre of land with bait using a hand-held spreader, and it takes two people an hour to locate and treat every colony in even a moderate infestation on that same acre (and they would probably miss a significant percentage of the colonies). With a bait, there is no need to search out any colonies since the ants find the bait themselves.
Charts 2 and 3, left, show the results of a test conducted in East Texas in the fall of 2004 that is probably the most “textbook” trial I have conducted in 16 years of fire ant research. Advion and Talstar have their usual, extremely fast control, followed by Amdro, ExtinguishPlus and TopChoice. By the time Distance kicks in with the hot weather in the spring, fast-acting plots already are getting reinfested. Talstar appears to “break” after about eight months, while TopChoice is still going strong. Speed versus duration — it's almost always a tradeoff.
My team and I also have initiated two projects designed to demonstrate the concept of targeted treatments. One is a 9-hole golf course. The map in Photo 1, page 30, shows an aerial photo of the course with our treatment plan overlaid on it. We prepared several treatment options (see Table 1, page 29). For our purposes, we used maximum control on the front half, with moderate control on the back. Due to budget constraints, the management likely will drop to monitored or even super-economy in the future. Initial results show close to 100 percent control of ants in treated areas through two months. Because this course had an existing fire ant problem, we treated the high-traffic areas with Advion.
The second map, shown in Photo 2, below, is of a high school campus. The maintenance manager already was using TopChoice on his sports fields and playgrounds; however, the fans had to dodge dozens of fire ant mounds outside the stands. We simply filled in the gaps by treating with Extinguish Plus, using about 25 pounds ($200 worth), for virtually complete coverage. Why treat parking lot islands and roadsides? People stand there when they get out of their cars. Why treat behind the school where the HVAC equipment is located? Fire ants are notorious for shorting out relays, air-conditioning units and transformers. Need to justify treatment costs to your superintendent? Figure how much fire ant bait you can buy for the costs to repair a shorted-out air-conditioning compressor.
Fire ant control is not about killing fire ants, it's about preventing fire ant problems — stings and electrical shorts — and keeping those fairways and greens nice and smooth. An effective control program starts with a diagram of your site and knowing its use patterns. By selecting the proper balance of speed of control, duration of control and cost based on those needs, you easily can design a highly effective, surprisingly inexpensive fire ant management program that can be maintained for a few hours of labor per year. The potential for economic loss and human injury versus ease and low cost makes fire ant control an issue you can't ignore.
Dr. Charles Barr holds a Ph.D. in Rangeland Ecology and Management from Texas A&M University. He has worked in fire ant research for the past 16 years, specifically on the control of red imported fire ants. His areas of emphasis include product testing, biological control and the promotion of economically feasible fire ant control in the agricultural sector through integrated pest management practices.
|Acres||Maximum||Moderate||Monitored||Super Economy||Whole property|
|Tees, pool clubhouse||1.4||A+TC
||A+ TC, $364||Bait
||Bait × 2, $34||Bait × 2, $1,512|
||Bait × 2, $33||Bait × 2, $33|
|Fairways||24.5||Bait × 2, $588||Bait × 2, $588||Bait × 1, $294||None|
|Rough||35.75||Bait × 1, $429||None||None||None|
|Labor, Application Equipment||1.5 days, manual and motorized||6-8 hours, manual and motorized||3-4 hours, manual and motorized||2-3 hours, manual only||2 days, motorized|
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