PPC115 | Technical

Laurence Barnard, Country Business Manager at BASF Pest Control Solutions shares his advice on best practice, as well as outlining important considerations for safe and effective pest control.

When it comes to recurring and severe infestations, it can be a minefield for pest controllers to determine the best approach to staying in control, whether it be via a permanent method or a long-term baiting programme. Both methods have limitations and precautions to consider, and with guidance frameworks ever-changing, it is easy to become unclear on what is considered the most suitable approach.

Permanent baiting

I think the easiest way to explain the meaning of permanent baiting is to use the term ‘insurance baiting’, or placing bait in areas of no current issues, but where you deem the risk of infestation or reinfestation as very high. This could be due to a rodent problem in neighbouring buildings where you have no access, regular incoming goods from infested sites, or simply the nature of the site you are trying to protect.

This approach helps to mitigate the risk of a full-blown rodent infestation by pre-emptive targeting of areas that are most vulnerable.

The aim for permanent baiting is to prevent and protect, by baiting target points using secure tamper-resistant boxes. Pest controllers can position these bait boxes inside and outside of buildings, but this does not cover sewers or open areas. If permanent baiting is to be implemented outside, some extra precautions should be taken. Remember, too, that only trained professionals can undertake permanent baiting.

When baiting outdoors, non-chemical methods should be considered first, such as non-toxic monitoring products, traps and increased preventative measures like proofing and environmental management as part of an ongoing integrated pest management (IPM) strategy. Not only is this much more cost-effective, and offers a more targeted approach, but it also reduces the risk to non-target species.

If a chemical approach is required, it’s vital to know that not all products are authorised for lawful use.

Cholecalciferol rodenticides like Selontra® are authorised for use when permanent baiting, whereas only a selection of rodenticides containing the active bromadiolone and difenacoum are approved for this use, so always ensure you refer to the product labels before proceeding. Baits containing the actives brodifacoum, difethialone or flocoumafen are not authorised for permanent baiting.

It is also of paramount importance that the user completes a full environmental risk assessment (ERA) prior to any working on the site, to determine the most appropriate form of action.

Long-term baiting

A long-term baiting strategy is usually employed if an infestation hasn’t been cleared in at least 35 days. This could be due to the volume of rodents, the nature of the site, or neophobia to new bait or bait boxes. In some cases, it could also be due to rodenticide resistance, making it difficult to reduce the infestation using some second-generation baits containing difenacoum and bromadiolone.

If you notice consistent bait uptake but no decline in activity after the 35-day mark, it is vital to review and establish the likely cause. When other elements have been excluded, such as new entry points or access to preferred food sources elsewhere, consider using an alternative rodenticide with a different mode of action. It might also be beneficial to implement traps as an additional method of control.

Just ensure that you refer to product labels when using a new product and continue to follow the product label conditions for long-term baiting.

Reducing the risk to wildlife

When using both the long-term and permanent baiting strategies, it is crucial to consider the risks to non-target species. If it becomes evident that any non-targets, or a species not outlined as the intended target on the product label, such as voles, field/wood mice (Apodemus sylvaticus), have consumed the bait, then the rodenticide should be removed immediately to protect wildlife and the reputation of the pest controller.

Pest controllers are required to carry out an ERA, with consideration to potential poisoning of non-target species, the potential risk to human health and to determine if the site is high risk.  Also ensure that CRRU documentation and advice is adhered to, to reduce the risks to wider wildlife, secondary-toxicity and also to protect yourself and your professional reputation.

Decision matrix for continuous baiting

Managing high-risk areas with Selontra® and Monitoring Paste

Selontra® is an effective rodenticide for use in permanent baiting strategies when there is a higher risk of secondary poisoning. Its active ingredient, cholecalciferol, is not persistent in the environment, does not bioaccumulate and is readily metabolised by rodents – in fact it is the only product on the market that is approved for use against wood/field mice (Apodemus sylvaticus)! 

Monitoring products, like Monitoring Paste from BASF, are also invaluable, not only giving pest controllers early indication of rodent activity but also offering a cost-effective alternative to permanent baiting with baits containing active ingredients.

Monitoring products is a cheaper way to reduce the risk of an infestation without using harmful toxic baits year-round when they are not required, and it is also much more cost-effective. Unconsumed bait can go mouldy or be eaten by slugs and snails, therefore proving ineffective and a waste of time, money, and resources.

As it is fundamentally the same recipe as Selontra®, minus the dye and active ingredient, it also ensures a smooth and quick uptake when swapped with the active alternative after rodent activity has been detected.