Can cat fleas build up a resistance to flea treatments? In other words can the species that is the cat flea evolve into something slightly different which cannot be killed by current flea treatments (insecticides). The evolutionary process is one in which fleas which survive are able to pass on their genes and therefore there are more fleas with genes that resist treatments. There are, though, other types of resistance which I won’t go into her for sake of clarity.
Note: On the Mumsnet website a number of mums have said on their forum that they believe that Frontline has lost its effectiveness in killing fleas while Advantage works better.
“Individuals with genetic traits that allow them to survive exposure to an insecticide/acaricide will pass genes on to the subsequent generation, thereby potentially increasing the percentage of a population that can survive subsequent exposure to the chemical”
This short article was prompted by Elisa’s comment. Quotes and information is from the study: Insecticide/acaricide resistance in fleas and ticks infesting dogs and cats by Tad Coles and Michael Dryden.
Using simplified language, resistance was stated as being a trait in the species of insect (e.g. the cat flea) which results in a notable increase in the percentage of fleas surviving treatments.
The conclusion from the study was as follows:
It is possible that cat fleas can become resistant to flea treatments but the only way to find out is to show scientifically “that the parasite population has changed” meaning genetically I presume. As far as I am aware no such research has been conducted.
Therefore, when, for example, a veterinarian’s client, a cat owner, attends the vet’s clinic, and says that the flea treatment is not working because the fleas are not being killed, the response is to check for reasons other than resistance to treatments.
In the words of the Coles and Dryden:
“it is essential to review the history and look for potential treatment deficiency, because the ultimate cause is much less likely to be actual flea or tick resistance. If reduced susceptibility to treatment is seen, then other more common causes must be ruled out before resistance can be considered as likely.”
In other words make sure the treatment is holistic – covers the entire household and is applied correctly. Potential examples of cat flea resistance to common commercially available treatments are much more likely to be a failure of the owner to tackle the presence of fleas effectively and in compliance with well-known guidelines.