No, it's not your impression. There are more and more cockroaches and they appear more frequently. This is confirmed by entomologists – biologists who study insects – and companies dedicated to treating pests.
“Climate change favors the proliferation of cockroaches: there are higher temperatures and for longer, and that allows them to grow and reproduce faster and more times,” summarizes Xavier Bellés, professor at the Institute of Evolutionary Biology (CSIC-UPF) who He has been researching and working with cockroaches for 42 years, especially with the blonde, the domestic one, which, along with the American one (reddish and somewhat larger), are the most common in urban areas.
And he predicts that, as temperatures rise, these insects will proliferate more: “When we raise them in the laboratory, at controlled temperatures, we observe that at 30º Celsius their biological cycle lasts a month, while at 25º it takes 48 days; so that, at a higher temperature (if it does not exceed 40º C), the larvae grow faster, reaching adults and reproducing sooner."
Furthermore, this acceleration of the cycle not only increases the number of cockroaches in an environment, but also gives them an advantage in surviving in human habitats because they develop resistance to insecticides in less time. "By sequencing their genome we have seen that they have more duplicated genes that give them resistance to toxins, that are useful for detoxification and that allow, when a new synthetic toxin is invented, the strain of cockroaches exposed to it to take very little time, "It only takes a few generations to be able to metabolize it and become resistant to that insecticide," explains Bellés.
Therefore, if with the increase in temperatures caused by climate change, cockroaches reproduce more times in less time, they skip the generations necessary to achieve resistance sooner and become immune to insecticides more quickly. “We are witnessing an endless race between humans who invent increasingly powerful insecticides and the cockroach that, after a few reproductions, invents how to metabolize it,” comments the researcher at the Institute of Evolutionary Biology (CSIC-UPF).
And he points out that the genome of these insects also reveals genes that give them a great sense of smell and touch, which gives them an advantage to access houses and places where they find food and better temperatures than in the sewers through unexpected spaces. “Domestic cockroaches have adapted to compete with man in their own home,” he emphasizes.
And what can be done to keep them at bay? The entomologist assures that they cannot be eliminated and we will have to live with them, controlling their movements and, in the case of pests, use professional means that are not toxic to people but that do not induce resistance in cockroaches either.
“He is a difficult opponent and there are no miraculous homemade solutions; What there is are alternative products to synthetic toxins, such as hormonal anti-growth or uric acid insecticides that work and are more environmentally friendly, but you have to put yourself in the hands of professionals.”
It is the same recommendation made by Jorge Galván, general director of Anecpla, the association of environmental health companies. "To fight against cockroaches, comprehensive management is needed by a professional who detects whether the product used is effective or not because, in addition to resistance, we have observed that cockroaches develop an aversion to certain products, that is, that the "The substance that is used to attract them stops attracting their attention and they no longer eat it, so you have to try other substances to eliminate them," he explains.
And he emphasizes that “if we find one or two cockroaches, we can apply a domestic biocide; But if it does not work or the problem is more serious, it is important to call a professional to apply another product that is effective, because if they do not die, those resistant cockroaches will continue to reproduce.”
He also advises taking extreme hygiene measures at home to prevent them from finding food and shelter. “It is important not to leave crumbs or residue that are palatable to cockroaches, because they enter and see where you don't, like under or behind the refrigerator,” agrees Bellés, who adds that although the presence of these insects does not entail a high health risk, , they can transmit some bacteria, such as salmonella, because they live and move through places where there is excrement and carrion, such as sewers.
The truth is that the greater presence of cockroaches in urban environments worries public health officials. The Barcelona Public Health Agency, which has already received more citizen notifications regarding sightings of these insects these days of high temperatures, has reinforced preventive surveillance and has increased the budget allocated to the fight against cockroaches.
However, Bellés explains that, in the case of Catalonia, “since it is raining less this year, we may see fewer cockroaches, not because there are fewer of them, but because fewer will come out of their shelters; “They like humidity.”
