Observation of living organisms in the 21st century

Biodiversity is in massive decline, mainly due to the increase in anthropogenic pressure on ecosystems (climate change, habitat fragmentation, introduction of exotic species, etc.). It is therefore more urgent than ever to make an inventory of living organisms in order to ensure that measures aimed at preserving this biodiversity are effective for all the species that compose it.

While the issues at stake have taken a dramatic turn, the tools available to scientists have evolved, whether due to improvements or to various technological developments. One example is the widespread use of photographic traps, which allow the observation of more discreet species without requiring an observer to be present on the site. In the same vein, the improvement in the quality of images from cameras integrated into mobile phones makes it possible to mobilise the public in participatory/citizen science projects. Each picture taken, once sent to a platform dedicated to the project, allows the photographer to know the name of the species observed, while the researcher obtains information on the geographical range of the species.

However, the most promising technique of the early 21st century goes beyond the visible spectrum, through the laboratory.

Environmental DNA or metabarcoding

Rather than basing the inventory on the species that might be observed on a site, we are interested in the DNA content of that site. To do this, we will target a specific DNA fragment called a “barcode”. Depending on the type of organism considered (plants, insects, mammals, fungi, bacteria, etc.), the fragment may be different. However, a barcode is chosen because it meets two criteria

• individuals of the same species have similar barcodes
• different species have different barcodes

This technique avoids the randomness of visual observations. It allows microscopic species to be recorded (and is therefore more complete), and also leads to greater distinction between species. It is sometimes difficult to separate two species on morphological characteristics alone. This method is also applicable to a wide variety of organisms (plants, insects, etc.), and has been used successfully in different types of environments, whether aquatic (detection of biodiversity in a lake), aerial (a volume of air passed through a filter), in soil, or even in dust swept up in a cabin in the woods. But you have to know what to sample and how to sample it.

Environmental DNA combined with the genius of the bee and the expertise of BeeOdiversity make it possible to substantially refine the characterisation of an ecosystem and to identify biodiversity deficiencies more precisely. How can this be done?

Bees as highly skilled pollen samplers

On average, over the course of an hour, a honey bee (Apis mellifera) will visit and collect pollen from about 250 flowers. The number of foraging hours will vary according to the time of year and the weather (rainfall, wind strength, but also temperature). Each time, she will bring her harvest back to a single place, the hive. Thus, 10,000 to 15,000 foragers will prospect the 700 hectares surrounding the hive during the 6 to 7 months of the beekeeping season. Honey bees are often considered as “super-generalists”, i.e. they will forage on a wide variety of flowering plant species. Thanks to this behaviour, it is possible to find not only the dominant plant species present in the environment, but also the rarer ones whose detection may be of greater interest (e.g. threatened, protected or invasive plant species). These bees therefore indirectly carry out an extremely thorough sampling of their immediate environment for BeeOdiversity. Only a tiny fraction of this pollen is collected for analysis. This is enough to ensure that the environment is representative, without compromising the colony’s development.