Bees, useful and intelligent

He said bee, he thought honey. This is the most common association we make. But, there are many more bee products, whether tangible (wax) or intangible (pollination), in addition to medicinal ones (propolis). Recent studies have shown that bees have also developed the ability to control parasites that infest them, through a sophisticated process, which begins with obtaining certain substances present in the nectar of specific plants. Subsequently, they are processed in the digestive system or with the help of the bees' intestinal microbiome, to produce bioactive and useful substances.

The reason for studying the topic is that, among the threats faced by pollinators – which are in clear decline around the world – are health problems, such as predators, parasites or diseases. These agents harmful to bee health can be introduced and disseminated via global trade routes and spread from managed bee colonies to wild pollinators. Its effects on bees are worsened by other stress factors to which colonies are subjected.

It is known that animals – including pollinators – have different microbiomes in their intestines, or that they are found in the environment in which they nest. These communities of microorganisms may be important for the health of pollinators, for example by defending them against disease or producing important nutrients. Understanding its functional importance, in addition to the contributions and interactions of microbiome species, can provide important information for the preservation of pollinators. Bee colonies can be maintained through new probiotics, or healthy microbiomes can be supported by foraging on plants with nectar or pollen containing substances that stimulate microbiome improvement.

Bioactive compounds

In an article published in May 2022, the team of researchers led by Dr. Hauke ​​Koch (University of Kew), in partnership with Professor Mark Brown (University of London), began their studies by collecting samples of nectar and pollen from lime trees and strawberry trees at Kew Gardens Botanic Gardens. The main objective was to discover which chemical substances were involved in antiparasitic activities, protecting bees from the Crithidia bombi parasite, a species of trypanosome that reduces the fertility of the queen and affects the survival of bee colonies. The researchers discovered that two compounds, found naturally in the nectars of these species, are activated alone by the bees' digestive system, by their intestinal microbiome or by a joint action of both (http://bitly.ws/qDet).

The first compound analyzed by the team, called unedone, was found in the nectar of Arbutus unedo, a tree that inhabits part of the Mediterranean region and the United Kingdom, and is known in Portugal as strawberry tree. Its flowers, rich in nectar and pollen, constitute an important food source for bees in autumn. From this nectar, bees produce honey with a bitter taste, which is appreciated in Europe.

Unedone was tested on laboratory-reared C. bombi individuals as well as bees. The researchers fed the bees a mixture of sugar syrup and pollen for two weeks. After the deadline, laboratory analyzes were carried out to check the presence of parasites. Due to the low incidence of parasitism in bees, a new test was carried out, with one group of bees receiving only sugar syrup and another with syrup added with unedone. Then came a very interesting discovery: unidone inhibits C. bombi infections only after interacting with the microbiome, as the initial metabolic processes in the bees' midgut inactivate its antiparasitic effect.

The second compound studied by the researchers was tiliaside, extracted from the nectar of the linden tree (Tilia sp.). However, contrary to what occurs with unedone, tiliaside is activated by the digestive processes of bees. Both compounds were presented as evidence of the benefits that food and microbiomes have in protecting and strengthening the health of pollinators, both for individuals and their communities and neighboring communities.

These discoveries represent an advance in scientific knowledge, allowing the improvement of bee management techniques, or providing conditions for wild bees, allowing infections of parasitic origin to be kept under control, improving the survival capacity of pollinators.

Box - Bees separate even numbers from odd numbers

To demonstrate that bees understand the difference between odd and even, researchers placed cards with different numbers of geometric shapes (triangles, squares, circles) next to bee feeders. A set of bees were trained to associate 2, 4, 6 and 8 with sugar water (which bees love!) and 1, 3, 5 and 7 with quinine, which bees hate. A second group was taught the opposite, odd numbers with sugar water and even numbers with quinine. See details at http://bitly.ws/qDhw.

Once the bees demonstrated their ability to choose the appropriate number associated with the sugar water feeder, they were faced with the choice between feeders marked with 11 and 12 shapes. It turns out that the bees had never been exposed to cards with either of these two numbers of shapes, as, in training, the quantities reached, at most, 7 or 8. However, those that were taught to associate even numbers with reward (water sugar) predominantly flew to the feeder with 12 shapes, while those trained to prefer odd numbers chose the feeder that contained 11 shapes. The success rate of the choices was greater than 70%, which provided confidence in stating that the difference was real and not due to chance, in accordance with the appropriate statistical treatment.

More than just a seemingly useless curiosity, this discovery raises interesting questions: do bees use mathematics in their daily work? Differentiating flowers by the number of petals or stamens? Enhancing the perfect hexagonal shape of honeycomb cells? Orienting yourself to look for food and return to the hive (or nest? Tracing collection routes that use less energy? New research will answer these questions.