According to a study recently published in Current Biology, humidity is as important as scent in attracting pollinators to any plant: this basic biological discovery opens new perspectives for agriculture in the time of global warming.
The world of plant-insect interactions has been dramatically changed by work done on visual and olfactory cues, without taking into account how many other factors play a role in plant reproduction and influence insect decision-making, pollination, and success. Researchers have in fact discovered that the weevil (Rhopalotria furfuracea), which pollinates the cycad (Zamia furfuracea), is sensitive to humidity as well as scent. Additionally, humidity serves as a signal for the tobacco sphinx (Manduca sexta) to pollinate the sacred datura flower (Datura wrightii). This shows that two very distantly related plants actively use humidity to encourage pollination: humidity is not just a result of nectar evaporation, but an active process of the flower, which passes through specialized cells, and these organisms they may even have evolved to prioritize moisture release because it attracts pollinators.
Until now, the study of pollination and plant-insect interactions had focused on visual and olfactory markers, signals that humans can also interpret: insects are much better than humans at sensing changes in humidity, carbon dioxide and temperature. While humans need relatively large changes in humidity before they can sense a difference, insects have specialized receptors that can sense tiny changes: even a change of 0.2% to 0.3% can cause the activation of a neuron.
Considering that climate change has a direct impact on these very things, it is crucial to understand how insects use all this information in their interactions with plants. For example, farmers and food distributors could use these findings to encourage pollination of food crops or to direct insects away from stored foods and into traps.