Pollinators are animals that help to transport pollen from one location to another in the plant reproduction process. Pollination is crucial to our well-being and to the survival of ecosystems. Pollination is used by about 85% of wild plants and over 70% of cultivated plants to reproduce. However, the diversity of pollinator species is declining due to climate change, habitat loss and the intensification of farming.

Maddi Artamendi, a researcher at the UPV/EHU, explained that “in most of the studies conducted on this issue across the world, plants were found not to bear fruit if no pollinator was present. Studies of this type have been mostly conducted on crop species, but that does not give a true picture, since the diversity of pollinators is going to decrease, is already decreasing, but is not going to disappear completely. What is more, wild plants were also taken into consideration as well as crop plants. We wanted to approach the subject from a more realistic perspective”.

A study led by Maddi Artamendi, a researcher in the UPV/EHU’s Department of Plant Biology and Ecology, and Ainhoa Magrach, an Ikerbasque Research Professor at BC3, has been published in the prestigious journal Nature Ecology & Evolution; it reveals that protecting pollinator diversity is essential not only to preserve nature but also to ensure the sustainability of ecosystems. “There is an urgent need to mitigate the factors that reduce pollinator diversity,” said the researchers.

The study reveals that the reduction in the diversity of pollinating animals has a negative impact on the reproductive success of plants (in terms of the number of fruits, the number of seeds and the weight of the fruits) and, what is more, “exerts a greater influence on wild plants than on cultivated plants”. They also saw that self-pollinating plants are also affected by the loss of pollinator diversity, “showing that it is very beneficial for these plants to exchange pollen”, explained Artamendi.

Moreover, the results show that wild pollinators have a greater influence on the reproductive success of plants than domestic pollinators (honey bees are usually classified as domestic pollinators). So “the decline in the diversity of wild pollinators further exacerbates the reproductive success of plants”, the researcher added. In particular, the loss of invertebrate pollinators is more pronounced than the loss of vertebrate pollinators; the loss of nocturnal pollinators is more pronounced than the loss of diurnal pollinators, and the loss of wild pollinators is more pronounced than the loss of domestic pollinators.

Meta-analysis of 207 pieces of research conducted across 46 countries

Meta-analysis, a method that uses statistical tools to synthesize data from a large collection of studies in a weighted manner, was used to conduct this study. So Artamendi and Magrach conducted a meta-analysis of the research that did not analyse the total loss of pollinators: a meta-analysis of 207 pieces of research conducted across 46 countries.

“We analysed research done across the world. We had to bear in mind that there are different varieties of plants depending on the climate, that the influence on one plant or another may have been different, and how large the sample was, etc. We took into account many variables so that all the pieces of research could be compared, and that is how we achieved a real, quantifiable result,” explained Artamendi. “Meta-analysis gives you a very global view,” explained the researcher, “to find out where the most research has been done, in which countries and climates, on which types of plants, etc. And that way you can see where the gaps may be, where the biases are...”

With all this, the researchers concluded that “all pollinators play a role, both in crop plants and in wild plants. We cannot focus on domestic pollinators alone. There are more pollinators, and we saw that they are all of great importance in the reproductive success of plants and in maintaining plant diversity. We should not focus just on crop plants and domestic pollinators, the view has to be opened out”.

Further information

This research is part of the thesis being written up by UPV/EHU researcher Maddi Artamendi, under the supervision of BC3 Ikerbasque Research Professor Ainhoa Magrach and the UPV/EHU lecturer and researcher Arantza Aldezabal.