INTERVIEW | PPC102 MARCH 2021
BASF has launched Selontra®, a new bait with a new active, cholecalciferol. PPC caught up with Helen Ainsworth, from BPCA member company and Selontra’s manufacturer, BASF to find out what the deal is with this new rodenticide.

Why is everyone talking about Selontra?
This is the biggest development in UK rodent control this century and offers pest controllers a new bait that rodents have no known resistance to. It is the first bait that can control even large rodent infestations in just seven days.
Selontra isn’t a second generation anticoagulant rodenticide (SGAR) and has a pretty unique mode of action. How does it work?
Cholecalciferol occurs naturally in all animals and is a key regulator of calcium concentrations in the blood. Toxic doses of cholecalciferol result in high concentrations of blood calcium, known as hypercalcemia.
Due to the great palatability of Selontra, a toxic dose of cholecalciferol can be consumed in just one day, enabling control to be reached more quickly compared to anticoagulants.
The unique way Selontra works obviously helps with resistance issues. How likely is it that UK rodents will end up with a cholecalciferol resistance?
Rodents have no known resistance to cholecalciferol which means it will be effective in areas of the UK where rodents have shown resistance to some SGARs.
We explored over 1,200 compounds to overcome resistance over the last ten years. Three years were spent developing Selontra and we are now very proud to be able to provide it in the UK.
Resistance in the UK has been detailed by the Rodenticide Resistance Action Committee (RRAC) in an online map. The spread of resistance is a threat to rodent control in the UK, so we need a resistance breaker, and Selontra gives us this.
Resistance to cholecalciferol is also highly unlikely to develop in the future because it is a naturally occurring essential prohormone. This means that rodents are highly unlikely to be capable of adapting to it.
To do so, they would have to evolve to tolerate physiologically fatal levels of calcium in the blood.
We’ve had cholecalciferol-based rodenticides on the market before. Can we really call Selontra new?
Cholecalciferol baits are not new. However, Selontra has been developed to ensure that a lethal dose is consumed in one day by having the most palatable formulation possible.
Prior to the launch, laboratory tests showed Selontra to be three to four times more palatable than other cholecalciferol baits. It’s also more appealing to rats than common farm feeds such as maize silage and piglet feed.
The palatability of the product is important because the rodent must consume a lethal dose in 24 hours for it to be effective. Selontra is even more palatable to rats than popular human foods.
We offered rats a beef burger or Selontra and, in our trials, the rats preferred Selontra and consumed more of the product in a day than the burger.
Maybe you should market Selontra as ‘better than a Big Mac’? Although that probably wouldn’t get past BASF’s legal department. One of the key selling points for Selontra is fast-acting. What makes it faster than a traditional SGAR?
Selontra works by the rodent having too much calcium in the blood. This triggers the rodent to lose appetite which makes Selontra the perfect product for areas where there is a biosecurity risk to humans or animals, such as in livestock buildings or food preparation facilities.
Rodents that have consumed a lethal dose of Selontra will stop feeding and moving 24 hours after eating a lethal dose. Death will be two to five days later, which is how Selontra can control even large infestations in just a week.
In laboratory trials, BASF has shown that anticoagulants take over three times longer than Selontra to control rats. The average time to death with Selontra is just under three days. By comparison, the meantime with an anticoagulant is nine days. Through the ‘speed baiting’ method, Selontra reduces the number of visits needed to achieve control, which will save users time and money.
You need to pass an online training course to be supplied with Selontra. Do we have to use it differently to other baits?
The label advises users to place sufficient bait and only return to replenish after two days.
The aim is to take out dominants with the first application, then subdominant and non-dominant rats. If consumption continues, bait can be replenished every week until control is achieved.
Tell us a bit about the block itself and what pest professionals can expect if they purchase some?
Selontra is a 20g bait that can be secured in bait stations or can be used in covered and protected baiting points. It is a soft block that is pale green and comes in a protective wrapper.
The non-permeable film has perforations to allow the bait to be detected by rodents while protecting the bait. Selontra is made of almost 99% food-grade ingredients and contains no animal fats, which are common amongst many other pasta baits.
The overall result is a bait that is both attractive and effective in extreme temperatures. It’s also resistant to mould growth, can be used as part of a permanent baiting strategy, and has a shelf life of three years.
What’s your thirty-second sales pitch for professionals thinking about using Selontra?
Selontra offers a new tool for rodent control at a time when problems with resistance are rising.
The new cholecalciferol active represents an opportunity to reduce the use of anticoagulants and balances performance and environmental impact.
Selontra is a resistance buster that will save pest controllers time and money.
We advise that anyone choosing to use the product completes the online training, adheres to the label and practices speed baiting accurately to realise the full potential of the bait to control rodents in seven days.
More information
Learn more about Selontra by taking BASF’s online training course (and you’ll pick up some CPD points on the way) training.selontra.com or join them for a series of seminar sessions at PestExtra.