The male cockroach has found the courtship in the rejection of sugar which allows him to normally attract the female, by modifying the composition of his offering to the one he is courting and by shortening the foreplay before taking action, according to a study on Wednesday.
By trying to bait cockroaches with sweet compositions, the trap makers could not imagine the consequences that this would have on the breeding strategies of the critter.
Thirty years ago, a study in the journal “Science” announced the appearance of a line of German cockroaches that had developed an aversion to glucose. Small in stature, Blattella germanica, the most common species of cockroaches, nests in kitchens around the world.
Traps to eliminate it have long worked by using its craving for glucose, which coats a deadly substance. Some of the insects have adapted by avoiding them.
But their aversion to sugar had an impact, because this substance was initially as important for food as for reproduction, notes the study published in the journal “Proceedings B” of the British Royal Society.
The male cockroach has a very particular tactic to curry favor with a female. It spreads its wings, secreting with a gland a nuptial juice based on maltose, a form of sugar. The female comes to taste it by climbing on her back, which then gives the male time to connect his genitalia to that of his partner.
Females who developed an aversion to sugar, to better avoid deadly traps, also shortened their antics with males.
Until the male cockroaches sharing this aversion found the parade, as explained in the study carried out by Ayako Katsumata, researcher at the laboratory of urban entomology of the American University of Raleigh, pioneer in this field.
The male cockroach has developed two techniques to achieve his ends.
It has modified the composition of its nuptial secretion, which contains five times less glucose than that of an ordinary cockroach, and above all two and a half times more maltotriose. This kind of sugar has a double benefit. It is very popular with females, and converts more slowly than maltose into glucose under the effect of the female’s saliva.
Second parry, the male cockroach springs into action in an average of 2.2 seconds, almost twice as fast as the average cockroach. Not leaving time for the female to convert part of her juice into glucose, and thus shortening the foreplay.
So much so that the big loser in the affair is now the ordinary male cockroach, which strives to produce a juice that is too rich in glucose, and which, slow to conclude, is sent back to the ropes by the female when she leaves. reports.
The study authors stress that understanding how the sugar-aversion trait spreads through the cockroach population is important if industry is to develop effective control strategies against the insect.