The perfumed language of flowers to attract insects


Not only shapes and colors, flowers and insects "communicate" also through the perfume according to specific, specialized or generalist strategies. In practice, the more the perfumes are simple and made up of few aromatic components the more they are addressed to a certain category of pollinators, if instead the fragrance of the flowers has a more complex bouquet the olfactory message will indiscriminately attract a wide range of insects.

The discovery of this language of flowers comes from a study carried out at the University of Pisa and published in an article in the magazine "Basic & Applied Ecology". Researchers from the Departments of Agricultural, Food and Agro-environmental Sciences and Pharmacy conducted the experimentation on fifteen species of wild flowers - including cornflower, gittaione, delphinium, nigella, wild carnation - and the related pollinators, such as bees, bumblebees, diptera and butterflies. The strips of spontaneous flowers were set up adjacent to the crops in the experimental wheat fields in agro-ecosystems affiliated with the University of Pisa and in the laboratory chemical analysis of volatile compounds was carried out. These strips, commonly defined as "wildflower strips", are in fact used for the survival of all those pollinating insects that are increasingly rare today both because of the growing scarcity of "entomogame" crops and for an increasingly less diversified use of the territory.

"The specialist and generalist interactions - stresses Stefano Benvenuti, a researcher at the Pisan University - therefore define the two models of co-evolution of insect flowers and whether the specialist strategy is more effective from the point of view of gene flow, as pollinators transfer pollen almost exclusively within the same species, however, it is certainly the one most at risk. This is because pollination depends on a fragile dependence on a few species of pollinators whose simultaneous presence with the blooms is unfortunately further threatened by the ongoing climate changes ".

The specialist flowers have in fact certain insects as pollen "carriers", suitably attracted by perfumes dedicated to them, which in turn have co-evolved mutualistically developing "tomentosity", ie pelurias, for the transport of pollen and elongated mouthparts to reach the nectar in semi-closed or particularly elongated corollas. The generalist flowers, on the other hand, do not select insects by accepting most of the pollinators which, however, prevents them from maximizing the efficiency of the transfer of pollen because in most of it it is also transported on flowers of different species.

"Understanding these particular interactions - concludes Benvenuti - means defending biodiversity and ultimately also preserving the beauty of the rural landscapes that surround us, such as ours in Tuscany renowned worldwide for their uniqueness".


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