Dick Murray, technical manager at Syngenta Australia, delves into detail about what it means to take an IPM approach to ant control. 

Ants are considered the most difficult pest to control amongst leading pest management professionals. This can be attributed to a number of reasons, but is thought to be mainly due to the increasing use of more targeted insecticides being applied in and around the home to cracks and crevices where surface crawling insects tend to inhabit. This has led to reduced use of broadcast residual sprays around the home and in turn, less residual ant control.

Integrated Pest Management for controlling ants includes:

  1. Attention to hygiene
  2. Exclusion through physical means
  3. Modifying ant habitats
  4. Insecticides.

Researchers agree that when managing ants you should consider their specific biology, with attention to both behavioural and feeding habits. Firstly, identify the ant you are dealing with so that the strategy can be tailored to its control. For instance, the feeding habits of ants vary regarding preference for sugars, fats, oils or protein and if the priority is to feed the brood, then there is a preference for protein.

Secondly, attempt to find the colony nest or at least access the trail. However, the ants on foraging trails that are seen in and around domestic and commercial properties are only a fraction of the number of individuals in a colony. At any one time less than 10% of the colony might be foraging, so it is important to realise that broadcast spraying with a knockdown will have very little colony impact.

The use of insecticides in ant management includes either repellents such as synthetic pyrethroids, or colony controlling agents such as non-repellent baits and chemical spray treatments.

A hot topic in the pest management industry is how to decipher what is and what is not considered a repellent insecticide, and furthermore, how repellent and non-repellent insecticides should be used to control ant pests.

In general, the concept of repellency for insecticides is really about the speed with which the insecticide acts on the pest insect. Insecticides like Syngenta’s Optigard Ant Bait Gel, Advion Ant Gel and Arilon Insecticide control exposed ants slower than pyrethroids, with knockdown times in the range of 90 to 120 minutes. Because of this delayed toxicity, ants are able to successfully recruit nest mates to the trail of the food sites so there is no apparent repellency.

Faster acting insecticides, like pyrethroids, generally knockdown exposed ants in less than 10 minutes which prevents the ants from forming a recruitment trail for others to follow, and inhibits recruitment to food sources. The result is that it appears as if the surfaces treated with pyrethroids are repellent to the ants. If insects are repelled away from a treated surface before picking up a lethal dose of insecticide the treatment will be less effective. In addition, insects that have contacted a pyrethroid insecticide may display hyperactivity as a result of the product’s irritancy and the erratic movements may carry them away from treated surfaces.

Advion Ant Gel and Arilon are formulated with indoxacarb and Optigard Ant Bait Gel with thiamethoxam. These are two of the most effective non-repellent actives available. Each is proven to exhibit a delayed response that allows foraging ants to carry the product back to the colony and transfer it to nest mates. Both gels have their own unique bait matrices that are highly palatable to all major species including sweet feeders. The use of non-repellent baits capitalises on the fundamental behaviour of ants, which is the exchanging and sharing of food amongst nest mates in an ant colony (i.e. trophallaxis).

It makes sense that insecticide control strategies that target the whole colony, such as workers (that feed the colony) and queens (that reproduce the colony) should be implemented. The best approach would be the use of a non-repellent gel such as Optigard or Advion, in combination with a non- repellent treatment such as Arilon. Below are quotes from pest managers who have had success with this approach.

Julie Trouten, branch manager of Amalgamated Pest Control Darwin said, “When Advion has been used with Arilon, you have the combination approach of a non-repellent bait and spray, thus ensuring the two options can work together.

“A big advantage of Arilon is that it can be used in conjunction with a bait such as Advion,” adding that new technicians can’t believe how good the results are. “The combination of the two products has been used where multiple nests were difficult to access and has certainly given us results.”

Using Arilon in conjunction with a non-repellent gel bait has also proved to be an ideal management approach for difficult ant jobs for Peter Morris, the branch manager of Amalgamated Pest Control in Townsville. “I had a difficult ant job in a block wall, and within days of treating with Advion and Arilon, the wall was completely absent of all live ant activity which could only have been achieved through colony control,” he advised.

No service callbacks on ant jobs is important for Gary James of Pestblue in Broken Hill. Many of his jobs are round trips of up to 600km and a service call can quickly turn a job into a loss. Mr James said, “I have been using Advion as my gel and Arilon as my surface spray for the last 12 months without one call back, I am very pleased with both products particularly as they can be used in conjunction in one treatment.”

An important requirement of baits is for the active ingredient to be distributed throughout the colony to all colony members. This transfer back to the brood (early life stages) is particularly important when you consider that up to 80% of the colony can be in that life stage. This transfer requirement is achieved by both Optigard (thiamethoxam) and Advion (indoxacarb) through their unique modes of action that spread quickly through the colony, controlling all life stages.

Thiamethoxam is readily transferred to individuals within ant colonies to control workers, brood and queens. It targets the nicotinic acetylcholine receptors in the insect’s nervous system, resulting in the death of the insect. Indoxacarb is the only current member of a class of insecticides called the oxadiazines with a new novel mode of action involving bio-activation in the gut of the insect. The bio- activated indoxacarb molecule then binds to the insect’s sodium channel in the nerve tissue blocking that channel and causing insect paralysis and death. The ideal option therefore, is to have a rotation of the thiamethoxam and indoxacarb chemistries in your ant control strategy to eliminate any insect resistance issues.

In summary, both Advion and Optigard non-repellent gels are attractive to ants foraging for food, assuring the consumption of the gel and their respective active ingredients, indoxacarb and thiamethoxam. Arilon is the latest non-repellent residual spray chemistry for ant control that is designed specifically for the pest control industry. Until the release of Arilon, it has been difficult to use sprays in the same area as bait products, as pyrethroid sprays tend to be repellent and unlike other non-repellents, Arilon can be used both indoors and outdoors. Arilon can be successfully used in conjunction with Advion and Optigard without negative effects.

In fact, gel consumption has been shown to improve when used in conjunction with Arilon as the spray can hydrate the gel. This combination of non-repellent baiting and spraying provides excellent control when treating ants in both commercial and domestic situations.

If you are unsure which gel is best for your job simply keep both products on board your truck and conduct a simple test. Place a spot of each gel down on ant trails and whichever gel is accepted first, continue with that one. As discussed, both Optigard and Advion offer delayed mortality, which is essential for colony control. For improved control, and large populations, apply Arilon with the gel. The use of these non-repellent options will lead to colony control, which is the sure way to avoid expensive callbacks.

Dick Murray, Technical Manager, Professional Pest Management Products, Syngenta Australia