As diverse as the types of ectoparasites are, so are the repellents against them. Perhaps you have already had to choose between a product containing pyrethrum or a product based on modified pyrethroids? There are differences in the degree of effectiveness, the duration of protection and the possible side effects.
Pyrethrum wird aus den Blüten verschiedener Tanacetum-Arten gewonnen
Natural pyrethrum has been a proven insecticide for centuries. It is extracted from the flowers of several species of chrysanthemum. The main active ingredients are pyrethrins, as well as cinerins and jasmolines. Pyrethrum is not UV-stable and is quickly degraded by exposure to daylight.
Pyrethrum acts as a contact poison that is neurotoxic to insects. The mechanism of action is based on the fact that the voltage-dependent sodium channels in the nerve membranes are blocked. When insects come into contact with it, they become paralyzed - the so-called "knock-down effect". The insects fall to the ground unable to move. Pyrethrum also acts as a repellent - an agent that repels insects.
The use of pyrethrum is permitted in organic farming. In the home, pyrethrum is used to protect against flies, mites, mosquitoes, cockroaches, ants, fleas and head lice.
The production costs of natural pyrethrum are high and the demand for insecticides alone cannot be met. This has led to the development of selective, highly effective compounds based on pyrethrum, known as pyrethroids, which are synthetic and above all cheaper.
Due to the targeted chemical modification, pyrethroids are more stable and more long-lasting in their effectiveness than natural pyrethrum. This sounds positive at first, but: Due to their longevity, pyrethroids can enter the body of mammals, even if only in small quantities. They can be absorbed through breathing, the skin or food. When used as a spray, the toxins are absorbed directly through the lungs into the bloodstream. There are therefore restrictions on the use of pyrethroids, particularly in cats, as they are less able to break them down than other animal species. Cats are also particularly susceptible to pyrethroid poisoning, which is usually fatal. However, some side effects can also occur in humans.
Babies, small children and cats are particularly sensitive to pyrethroids. In correspondingly high concentrations, pyrethroids can cause irritation of the skin and mucous membranes, burning eyes and an irritating cough. Symptoms of neurotoxicity such as headaches, dizziness, tiredness, weakness, loss of appetite, nausea and sweating can also occur.
The high and long-lasting efficacy of preparations containing pyrethroids speaks for itself. However, this increases the risk of side effects. As pyrethrum is broken down comparatively quickly, the risk of undesirable effects (side effects) is lower than with pyrethroids. Due to their lower effectiveness, preparations containing pyrethrum generally need to be applied more frequently or the protection renewed at shorter intervals.
