In the war against cockroaches, we are likely to suffer a crushing defeat. These small animals seem almost invincible, as revealed by the analysis of their DNA, conducted by researchers from the Normal University of South China.
In a publication published in the Nature Communications journal, Chinese scientists presented the secrets behind the resistance of a particular species of cockroach, the American cockroach, referred to by their scientific name Periplaneta americana. Its secrets lie in its genome which is out of the ordinary. It is indeed one of the most complex of this class of insects.
Made up of more than 20,000 genes, it is almost as massive as our own genetic heritage. Among the multitude of DNA sequences, researchers have identified several gene families that make the American cockroach an insect which can stand up to almost anything. ‘It's a tiny pest, but it has an incredible vitality,’ said lead author Sheng Li to The New York Times.
Particularly developed senses
The first formidable weapon the American cockroach has is its infallible sense of smell. It has a series of genes, the exclusivity of which have endowed it with a number of olfactory receivers, almost twice as many as that of the other species of insects.
‘These extensive olfactory receptors could help Periplaneta americana more easily detect traces and odours of food, especially fermented foods, that the American cockroach prefers,’ the researchers explain in their publication.
In addition to a sensitive nose, these unusual insects also have a particularly sensitive palate. They have more than 500 taste receptors, which, according to scientists, allow them to better adapt to various diets, and to avoid certain bitter, potentially deadly foods. This capacity to adapt is essential for their survival in inhospitable environments.
Urban housing is indeed their favourite area. And yet, this environment is particularly threatening for these small animals, which are potential victims of toxins and contaminants that proliferate there. But again, their genome saves them from a death that could have been unavoidable.
Enzymes against toxins
Many of the American cockroach’s genes orchestrate the production of enzymes that can break down any toxic substance, including pesticides. Their immune system is also much more powerful than that of their fellow insects. Even in case of injury, Periplaneta americana can cope. In the nymph stage, some of its genes allow it to grow back one of its limbs amputated by an enemy attack.
The identification of these multiple genetic peculiarities allows us to unravel the mystery behind the resistance of the American cockroach. Knowledge that could also now turn against it: researchers see each of the genes responsible for its survival as a potential weak point to attack it, in order to finally win the war against Periplaneta americana.