Resistance to Rat poison
In Pests in Autumn, Pests in December, Pests in February, Pests in January, Pests in Winter, Rats & Mice
Resistance to Rat Poison:
In my experience this (resistance to rat poison) is over exaggerated. Resistance to rat poison is often blamed when treatments fail when in fact there are other reasons why treatment failure occurs. If after c couple of weeks rat poison is still being consumed and rats are still present then immediately some pest control technicians or Enviormental Health Inspectors will put this down to resistance and either walk away or start some long investigation that will either be inconclusive or will find the gene for resistance in rat tails or other body parts containing DNA. (I will come onto this later.)
Rats normally have to feed on poison bait several days in a row (depending how much they eat at each sitting which depends on availability of other food, position in the social hierarchy & other factors) before consuming enough to kill them. So say they are not eating enough per feed or the bait runs out then the bait will disappear but some rats may survive who will breed, replacing rats that have been killed. There can be several reasons for this. It may be that only the ‘edge’ of the infestation is being treated, for example rats feeding from bird feeders next door & commuting in to feed will present a problem unless the whole area is baited and the food source removed. Rats may not eat enough or frequently enough if other foods are available. Even if they wanted to feed more on the baits, other rats may have eaten all the poison so there is none left or more dominant rats will hog the bait points, bullying less dominant rats to keep away or a combination of both. If there are not enough bait points, the baits are not replenished often enough or cover a wide enough area the treatment will fail.
PEST UK covers all of Berkshire, North West Surrey, South Oxfordshire and North Hampshire. West Berkshire and North Hampshire are supposed hot spots for resistance. Well we have had very few treatment failures due to this supposed problem. When tests are carried out then it is quite common to find the resistance gene in the sample. In our experience this does not mean the treatment will fail. Resistant rats are under normal circumstances under a disadvantage compared to other rats as the gene requires that they need high levels of Vitamin K. This is only available in large quantities form green crops such as Kale or in cattle food. This is rarely available.I believe the gene may be present any way in a high percentage of rats. We had a case in Newbury where the EHO was convinced that resistance was rife and even advised us not to use poison. After a failed trapping program (we were instructed to do this) we persevered with baiting and although this took longer than normal the treatment was a complete success.
Because in most cases the technicians at PEST UK guarantee rat treatments they take great effort to make sure the treatment succeeds unlike some other companies and local authorities. PEST UK is one of the largest ‘local’ companies in Berkshire so if resistance was a real problem we would know about it but so far it isn’t.