(ORDO NEWS) — A new study of spider habits by scientists from Canada has shed light on the mystery of female false widows attracting breeding partners.
It turned out that the secret lies in a special way of making the web, where special pheromones are mixed as ingredients, the release of which is regulated by the widow herself.
Attracting or finding a mate is essential for all animal species capable of sexual reproduction. The process can use signals of various nature – from sound and visual to vibrational and chemical.
The latter include the oldest form of communication signals – pheromones, the use of which has evolved in parallel in various taxa of animals.
Sex pheromones, also called sex attractants, that cause attraction to the source of the smell in organisms that perceive them, are best studied among insects.
Beetles, moths, ants, wasps and other representatives of this class of animals produce and secrete pheromones from special glands located in various parts of their body.
Spiders, although not insects, are very original in terms of the use of attractants: instead of spreading pheromones through the air, female spiders add them to the web when weaving nets.
Nevertheless, a number of details of this process are not completely clear and investigated. For example, how and in what organ does this very addition of pheromones to the web take place, how pheromones are then released from spider webs to attract a partner, and also how female spiders can (and can) control all this.
To answer these questions, scientists from Simon Fraser University (Canada) studied female false widows ( Steatoda grossa ) – a deeply invasive species that lives mainly in residential buildings, where they are able to breed all year round.
A total of 163 representatives of S. grossa participated in the study , 93 of them were sexually mature adult virgin females, and another 70 were young immature females.
For three days, on a special prismatic frame, they weaved nets, which were then collected by scientists and analyzed for the content of attractants.
To the surprise of the authors of the study, three previously unknown pheromone components were contained not only in the web of mature females, but also in the web of younger false widows.
However, as it turned out, in order for these three components of pheromones to become an effective attractant, attract partners and force them to court the female S. grossa , they must be chemically broken down.
For this, a special enzyme is provided in the composition of the web – carboxyl ester hydrolase. It turned out that it is precisely this component that is missing in the composition of the web of young false widows, who are not yet ready for mating and therefore are not able to weave an “attractive” web.
At the same time, according to the authors of the article, the speed of this enzyme directly depends on the pH value of the environment, that is, in this case, the web. Thus, by changing the pH of the released web, S. grossa females can regulate its attractiveness to males.
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