Application of a broadcast fire ant bait treatment to a lawn using a hand-held spreader.
Several products said to be "organic" (of natural origin) are currently marketed for fire ant control. These products may or may not be registered as pesticides by the EPA and the appropriate state regulatory agency. In 1996 the EPA established that certain ingredients that pose minimum risk to users no longer require EPA approval to be marketed as insecticides. Many of the "organic" products fall into the minimal risk category. One consequence of this decision is that the EPA does not require efficacy data on minimal risk products unless the target pest carries specific diseases. Therefore, not every product sold for fire ant control is supported by research-based evidence that it is effective against fire ants. Note that not all products that contain naturally occurring active ingredients are completely organic; some contain non-organic inert ingredients. Products approved as organic are certified by the Organic Materials Review Institute (OMRI). OMRI provides an independent review of products intended for use in certified organic production, handling, and processing. Acceptable products are OMRI Listed® and appear on the OMRI Products List. State and federal organic certification programs are limited to food crop and livestock production systems where only approved organic products are allowed for use. In other use sites such as landscapes including turfgrass and ornamental plant maintenance, "organic" products are defined by the user and may include home remedies and physical and mechanical methods. In this section, we will discuss the use of organic insecticides and not consider these other methods that some may consider "organic". Please remember, some “organic” treatments are not necessarily safer or less toxic than conventional insecticides and should always be used as directed and with care.
Organic Fire Ant Bait TreatmentOMRI Listed® organic fire ant bait products currently on the market contain spinosad as the active ingredient. Bait products may be used by broadcasting over an entire area or as individual mound treatments. In most cases, a broadcast application according to label directions is the most effective way to use bait products. Fire ants forage for the broadcast bait and carry it back to the mound to kill the queen. Individual mound treatments with baits are also effective if you have a small number of mounds in your yard and can locate them for treatment. If colonies are young or if the weather is hot and dry, mounds may be difficult to locate. The advantage to broadcasting baits is that this method is effective on mounds that you cannot see. Organic Individual Mound TreatmentsOMRI Listed® fire ant products for individual mound treatments contain either spinosad or d-limonene (a component of citrus or orange oil). Apply mound drenches by mixing the specified amount of insecticide per gallon of water and pouring onto the fire ant mound. The ants are killed by contact with the insecticide. Therefore the amount of drench needed to saturate the mound depends on the size of the mound. One gallon is sufficient for small mounds, but two gallons or more may be needed for large mounds. Use a watering can, or similar container, to mix and apply the drench according to label directions. Do not disturb the mound before drenching. Be sure to use enough drench volume to saturate the mound. Not using enough drench to thoroughly soak the mound is the main reason for control failures with mound drenches. D-limonene kills contacted ants within minutes but has little residual effect, so mounds need to be drenched thoroughly and quickly in order for the drench to be effective. Any granular products (other than baits) should be applied to the mound according to label directions. These are usually watered in using one or two gallons of water depending on mound size. Use of Both Baits and Drenches - The Two-Step MethodOne of the most effective ways to control fire ants with these organic treatments is to use the baits as the primary control program. Then, a week or two later use individual mound treatments to spot treat mounds that survive the bait treatments or that ‘pop up' between bait treatments. The individual mound treatments can be either mound drenches or individual mound bait applications. This is called the The Two-Step Method. Other Organic ProductsThere are several other products that are OMRI Listed® for general ant control. Some of the active ingredients contained in these certified organic products are spinosad, d-limonene or orange oil, mint oil, clove oil, diatomaceous earth, pyrethrins, pyrethrum, cottonseed oil and canola oil. These products can be used for fire ants if label directions are followed. There are other products on the market that contain naturally occurring active ingredients that are completely organic along with naturally occurring inert ingredients that are not OMRI Listed®. However, some products sold as "organic" or "eco-friendly" with naturally occurring active ingredients may contain non-organic inert ingredients. So, you need to read the label carefully if the product is not OMRI Listed® to make sure you are getting an all natural, wholly organic product. Sources and Modes of Action of Organic Active IngredientsSpinosad, which includes spinosyn A and spinosyn D, is derived through the fermentation of a naturally occurring organism. These insecticides have a unique mode of action that is different from all other known insect control products. Spinosad causes excitation of the insect nervous system, leading to involuntary muscle contractions, prostration with tremors, and finally paralysis. These nerve toxin effects are consistent with the activation of nicotinic acetylcholine receptors by a mechanism that is novel and unique among known insecticidal compounds. The citrus or orange oil component, d-limonene, is a cytotoxin that kills cells after entering the insect body through direct contact. Other essential oils or components of essential oils have come on the market in the last few years in a variety of pesticides. Essential oils are volatile, highly concentrated substances extracted from plant parts, including the oils of cedar, cinnamon, citronella, citrus, clove, eugenol (a component of clove oil), garlic, mints, rosemary, and several others. As insecticides, they vary in their modes of action, but most work as contact killing agents only, so re-treatment may be needed. Some are promoted as repellents. Some essential oils used as pesticides may work by disrupting an insect neurotransmitter that is reported to be not present in people, pets, or other vertebrates. Most of these ingredients are generally regarded as safe for mammals by the United States Food and Drug Administration when used as directed. Many are even used extensively as flavorings and scents in foods, cosmetics, soaps, and perfumes. Pyrethrum is the source of natural insecticides made from the ground dried flowers of certain species of a chrysanthemum plant. The ground flowers contain a mixture of several different compounds called pyrethrins and cinerins. Pyrethrins are natural insecticidal compounds that are extracts of the chrysanthemum plant. Pyrethroid insecticides, such as permethrin, bifenthrin, cypermethrin and others, are synthetic versions of this naturally occurring insecticide. Pyrethrins, like pyrethroid insecticides, bind to sodium channels that occur along the length of nerve cells. Sodium channels are responsible for nerve signal transmission along the length of the nerve cell by permitting the flux of sodium ions. When pyrethrins bind to sodium channels, normal function of the channels is obstructed thereby resulting in overexitation of the nerve cell and, consequently, a loss of function of the nerve cell. Diatomaceous earth (DE) acts as a desiccant by scratching and absorbing the waxy layer that makes up part of the insect's exoskeleton. DE is most commonly applied as a dust to ant foraging trails to kill foraging ants; however, this use will have little or no effect on the ant colony or nest. Insecticide grade DE products are available, but when applied as a dry dust to the top of an ant mound or as a drench, fail to contact ants. Also, high humidity in ant mounds prevents desiccation. Thus, this ingredient acts more as a carrier in fire ant products that list DE as an active ingredient. |
