Cockroaches are developing resistance to insecticides

As bacteria develop resistance to antibiotics more and more efficiently over time, even cockroaches, to a lesser extent, are developing different degrees of resistance to the best insecticides. This was revealed by a study by Michael Scharf, a professor in the Entomology Department of Purdue University.

In his study, published in Scientific Reports, the researcher studied the German cockroaches, noting that it has become more difficult to eliminate them. This problem, which is more widespread in urban areas, opens up what could be one of the new challenges that will affect the future of humanity to combat pathogens of pathogenic bacteria, similar to what is done today with mosquitoes.

The cockroaches, in particular their saliva and their feces, carry several potentially dangerous bacteria that can cause, for example, allergies and asthma and several other conditions especially in children. In the future, it may be impossible to control the parasites of cockroaches with simple chemicals, those that are today contained in the most classic insecticides.

The researcher, together with his colleagues, tested three insecticides of different classes for repeated periods. In another phase, they used only one insecticide for which the cockroaches had developed an initial resistance, however of low level. In other phases, they still rotated the use of various insecticides of various classes. The result they have obtained is that in most cases they have had problems in containing populations and that the best result was obtained by using several insecticides of different classes simultaneously.

What the researchers observed is that insecticide resistance increased four to six times in a single generation, much faster than one might have thought. In fact the experiment lasted only six months: evidently, the same researchers believed that gender adaptations could have taken place only after years or in any case after many more generations.

Female cockroaches are characterized by a reproductive cycle of three months during which they can give birth to up to 50 children. This means that evolution can accelerate more easily: even if very few of the children show resistance to an insecticide or cross-resistance to more insecticides, the population can afford to re-explode after a few months with the advantage of resistance.