Dick Murray, technical manager at Syngenta Australia, outlines the range of options available for controlling ants, including gel baits and residual sprays. 

Amongst leading pest management professionals, ants are now considered the most difficult pest to control. To get on top of an ant problem and provide lasting control, the homeowner also has a role to play in an integrated pest management (IPM) program.

An IPM program for ant control would include activities in the following areas:

  1. Attention to hygiene
  2. Exclusion through physical means
  3. Modifying ant habitats
  4. Application of appropriate insecticides.

In focusing on the application of appropriate insecticides, researchers agree that when managing ants, you should consider their specific biology, with attention to both behavioural and feeding habits of the target pest ant.

Species identification is key for baiting

The first key step in an ant control program is to identify the ant you are dealing with so that the strategy can be tailored to its control. The identification of species is key to understanding how many bait applications are needed as multi-nesters and multi-queen colonies are more likely to need repeat applications.

For many species, food preferences vary throughout the year depending on the colony’s priority and their nutritional requirements. Some well-known sugar preferring ants, such as the white footed house ants and Argentine ants, will show a preference for protein in the summer months to answer the needs of increased egg laying and the developing young life stages of the colony at that time of the year.

Native ants are generally easier to control. For instance a single bait application near the nest entrance will control the green-headed ant in hours. The black house ant normally succumbs to a single sugar bait placement, whereas the white footed house ant can require repeated baiting.

Repellent v non-repellents

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

Faster acting insecticides, like pyrethroids, generally knockdown exposed ants in less than ten minutes, which prevents the ants from forming a recruitment trail for other ants to follow, therefore inhibiting 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 as a residual spray.

Although pyrethroids have commonly been used for ant control, it is important to understand that any one time less than 10% of the colony might be foraging. So directly spraying foraging trails with a ‘knockdown’ product will have very little colony impact.

Insecticides such as Syngenta’s Optigard Ant Bait Gel, Advion Ant Gel and Arilon Insecticide, control exposed ants more slowly than pyrethroids, with knockdown times in the range of 90 to 120 minutes. This is actually a good thing – with this delayed toxicity, ants are able to successfully recruit nest mates to the trail of the food sites so there is no apparent repellency. As a result there is a good transfer of insecticide.

Advion Ant Gel (main picture above, being consumed by crazy ants, Nylanderia pubens) and Arilon Insecticide are formulated with indoxacarb and Optigard Ant Bait Gel with thiamethoxam. These active ingredients are two of the most effective non-repellent actives available. Each one 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, affecting all life stages.

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 is highly effective in colony control, as these treatments capitalise on the fundamental behaviour of ants, which is the exchanging and sharing of food amongst nestmates in an ant colony (trophallaxis).

Product performance

It makes sense that insecticide control strategies that target the whole colony, including workers (that feed the colony) and queens (that reproduce) should be implemented. The best approach is proving to be the use of a non-repellent gel, such as Optigard or Advion, in combination with a non-repellent chemical spray treatment, such as Arilon.

According to Simon Lean, Rentokil Australian technical manager, “It is new products and technologies that are helping to shape the pest control industry.”

Mr Lean said that companies such as Syngenta were leading the push towards new technologies and that Advion and Optigard gel formulations that target ants were widely used by his organisation with very good results. “These gel products are well formulated, very attractive, as well as being very easy to use. Their formulation and safety are key factors as to why we actually get to use them.”

Using Arilon in conjunction with Advion gel bait has also proved to be an ideal management approach for difficult ant jobs for Peter Morris, 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 be achieved through colony control,” said Mr Morris.

An added advantage of Arilon is that it is a non-repellent residual spray that can be used both indoors and outdoors which is particularly important when you have some ant species, such as white-footed house ant (Technomyrmex spp.), that will nest both inside and out.

No service callbacks on ant jobs is particularly important for Gary James of Pestblue in Broken Hill. This is because many of his jobs are round trips of up to 600km and a service call can quickly turn a job into a loss.

“I have been using Advion as my gel and Arilon as my surface spray for the last 12 months without one call back, so I am very pleased with both products, particularly as they can be used in conjunction in one treatment,” commented Mr James.

Odorous house ants feeding on Advion

Scott Hammond from Hammond Pest Management in Jindabyne uses Optigard and gets feeding ‘straight away’. After only two baiting applications he achieved elimination of big interlocking nests of black house ants. Mr Hammond says he has had no call backs since using Optigard against all levels of infestation.

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 had 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.

The ability to use a non-repellent spray, such as Arilon in conjunction with higher performing gels, such as Advion and Optigard, has provided pest managers with a winning combination, providing excellent control of ants in both commercial and domestic situations.

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

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