Chris Mills from Bayer Pest Management outlines the benefits of baiting when it comes to cockroach control.

Controlling German cockroaches can present one of the more challenging jobs in commercial pest control. Whilst there are many different approaches and application methods such as sprays, dusts, aerosols and even foams, gel baiting can provide many benefits.

A gel bait is targeted specifically at cockroaches and is applied to harbourage areas, cracks and crevices. This method of application is recognised as a lower risk alternative to liquid sprays as gel baits contain a relatively small amount of active ingredient (AI) and are applied at a much lower rate per square metre of the property.1 Baiting significantly reduces the amount of chemical used in the vicinity of humans. By applying gel baits, pest managers also gain a better understanding of the environment they are treating, enhancing the potential to educate the customer about managing their cockroach issue.

Gel bait matrices are formulated as a palatable food source that the target pest will ingest. AIs chosen for gel baits are slow acting, which allows for far greater ‘transfer’ or secondary kill with social insects such as German cockroaches. Secondary kill occurs through behaviours such as trophallaxis (food exchange), coprophagy (consuming faeces), necrophagy (consuming dead cockroaches), and emetophagy (consuming vomitus). This is how a gel baiting treatment can penetrate far beyond the cracks and crevices where bait has been applied and well into harbourage areas or nests within wall cavities, machinery, splashbacks, and voids that cannot be treated with a liquid spray. Even early instar nymphs hidden away inside inaccessible harbourages can be affected by the secondary kill behaviours associated with gel baits.

Having a slow acting AI formulated into a palatable food source can also be advantageous over a liquid spray formulated with a similar slow acting AI that does not contain a food source. Spray applications rely more heavily on the target pest coming into contact with a treated surface, as opposed to gel baits which are designed to take advantage of behaviours promoting secondary kill.

Bait palatability is everything. You could have ‘the best AI in the world’ in your bait formulation, but it won’t do anything if the cockroaches don’t eat it! In other words, the bait needs to be highly palatable to cockroaches to ensure ingestion of the AI. Good sanitation and hygiene practices are also important to ensure your bait is the most attractive food source available to the target pest.

An ideal bait matrix should be highly attractive to both adults and nymphs and not contain any of the ‘big eight’ food allergens: eggs, soy, seafood, milk, wheat, shell fish, tree nuts or peanuts. The bait should remain stable both in the tube and on a surface, remaining palatable after application for up to 12 months. These are all qualities found in Bayer’s Maxforce gel range.

Bait aversion is considered to be more of an issue than AI resistance in relation to cockroach baiting. In countries where the problem is well documented, gel baits containing certain food ingredients are rendered useless because cockroaches will not feed on them. This may be the case where one bait has been used for a long period of time. Bait rotation is imperative in treatment management programs where long-term baiting is relied upon for control. Bait aversion is not currently considered an issue in Australia as pest managers have adopted sensible and planned gel bait rotation practices.

The Bayer Maxforce range contains three different cockroach bait gel matrices developed in light of the ongoing global research into bait aversion. Having three different formulations gives Australian professional pest managers the flexibility to manage bait rotation and avoid bait aversion.

More and more restrictions, regulations and standards will continue to govern what control methods pest managers can use, where they can use them and how they can apply them. Certain areas and surfaces that we can spray today may not be allowed to be sprayed tomorrow. For these factors and other benefits already outlined, gel baiting is likely the best method of cockroach control for your business moving forwards.

Chris Mills, Territory Sales Manager (QLD/NT) Bayer Pest Management

1 Dhang, P. (2011). Urban Pest Management: An Environmental Perspective.

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