Local Conditions Could Save Pollinators
This post is written by Paolo Biella, ZooPlantLab, Department of Biotechnology and Biosciences, University of Milano-Bicocca, Italy.
Honeybees, bumblebees, solitary and social wild bees, hoverflies and other types of flies, butterflies, moths and even beetles are among the most frequent insect pollinators that visit flowers. However, pollinators and insect populations worldwide are disappearing at alarming rates. Even though most people love pollinators, little is usually done to halt the decline. Human activities alter natural systems at different levels. At a landscape scale, pollinator populations can be put at risk through habitat loss and fragmentation caused by replacing natural habitats with cement structures or intensive agriculture. Smaller scale management decisions, including unwise and pollinator-unfriendly management of green areas that decrease flower diversity or interfere with nesting, use of long-lasting pesticides or spaying them during plant flowering, or introduction of competitors or harmful diseases that do not naturally occur in the area can also trigger insect population declines. Cumulatively, these changes dramatically impact the ecosystem services provided to humans by biodiversity, including those related to agricultural production (e.g., pollination), regulation, health and ultimately human wellbeing.
Increasingly, the scientific community has come to recognize that losing pollinators will have significant consequences. Crop markets are strongly dependent on the pollination by animals, and animal-pollinated crops often have higher sale prices than pollinator-independent crops. It has been estimated that if there is a complete loss of pollinators, the average global supplies of fruits, vegetables and nuts will decline by 16-23 percent. Furthermore, pollinators are directly responsible for up to 40 percent of the world’s supply of critical micronutrients, including vitamins A and C, calcium, fluoride and folic acid. Insufficient intake of key micronutrients from pollinator-dependent species of fruit, vegetables and nuts constitutes an important risk factor for a number of diseases.
For all of these reasons, my colleagues and I have been studying pollinator diversity and their interactions with plants in several countries, including Tanzania, the Maldives, Italy and the Czech Republic. In the Czech Republic, we tested how simplification of the plant community impacts pollinator abundance, interactions with plants and pollination efficiency. We explored these effects by setting up field treatments specifically designed for testing these hypotheses. We also tested the effects of insect declines by experimentally decreasing the number of foraging bumblebees in a number of commercial colonies and assessed whether and how the remaining workers changed their foraging rates and the diversity of pollen collected.
In Tanzania, Italy and the Maldives, we are now studying the effect of landscape structures on pollinators, plants and their interactions in urban and agricultural areas, together with my colleagues at the ZooPlantLab at the University of Milano-Bicocca and other international collaborators. The Maldives are particularly exciting to be working in because island systems function as natural laboratories. Essentially, because pollinators cannot leave the island, islands are relatively more efficient for testing land-use impacts on pollinators. Furthermore, the knowledge of the pollinator fauna in the Maldivian islands is quite limited, which makes every observation a potential discovery.
In Northern Italy, we are also studying the impacts on pollination posed by the fast and widespread urbanization processes taking place in the area; a situation that is emblematic of what is happening in many areas around the world.
In Tanzania, we studied three different farming systems, comparing small urban farms, fields grown with organic techniques and areas of intensive agriculture. There, we obtained a number of intriguing results. One of the most relevant findings is that the way single farms are managed in terms of wildflower diversity and cover plays a big role in determining pollinator species richness, abundances and interactions with plants. In other words, the management of small areas could play a major role in enhancing pollinator diversity and pollinator services. These results are very encouraging because it means that even small-scale management and pollinator-friendly practices have a large capacity for rescuing pollinator populations. And every small step we can take to protect pollinators will be necessary as we wait for more enlightened and sustainable landscape planning, particularly in growing urban centers.