According to the first global assessment of pollinators, a growing number of pollinator species worldwide are declining and are being driven toward extinction by diverse pressures. The decline is primarily due to changes in land use, intensive agricultural practices and pesticide use, alien invasive species, diseases and pests, and climate change.
A two-year study was conducted and released last week by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), an independent intergovernmental body for assessing the state of the planet's biodiversity, its ecosystems and the essential services they provide to society.
The assessment, titled "Thematic Assessment of Pollinators, Pollination and Food Production," is a groundbreaking effort to better understand and manage a critical element of the global ecosystem. It is also the first assessment of its kind that is based on the available knowledge from science and indigenous and local knowledge systems.
"Pollinators are important contributors to world food production and nutritional security. Their health is directly linked to our own well-being, " said Vera Lucia Imperatriz-Fonseca, Ph.D., co-chair of the assessment and Senior Professor at the University of São Paulo.
There are more than 20 000 species of wild bees alone, plus many species of butterflies, flies, moths, wasps, beetles, birds, bats and other animals that contribute to pollination. Pollinated crops include those that provide fruit, vegetables, seeds, nuts and oils. Many of these are important dietary sources of vitamins and minerals, without which the risks of malnutrition might be expected to increase. Several crops also represent an important source of income in developing countries from, for example, the production of coffee and cocoa. Pollinators also contribute to crops that provide biofuels, fibers, medicines, forage for livestock, and construction materials. Some species also provide materials such as beeswax for candles and musical instruments, and arts and crafts.
According to the study, the volume of agricultural production dependent on animal pollination has increased by 300% during the past 50 years, but pollinator-dependent crops show lower growth and stability in yield than crops that do not depend on pollinators. In addition, nearly 90% of all wild flowering plants depend at least to some extent on animal pollination.
Factors affecting pollinators
The assessment found that an estimated 16% of vertebrate pollinators are threatened with global extinction with a trend toward more extinction. This number is even greater for island species - 30%.
Mostt insect pollinators have not been assessed at a global level, however, regional and national assessments indicate high levels of threat, particularly for bees and butterflies - with often more than 40% of invertebrate species threatened locally.
The study found that pesticides, including neonicotinoid insecticides, threaten pollinators worldwide, although the long-term effects are still unknown. A pioneering study conducted in farm fields showed that one neonicotinoid insecticide had a negative effect on wild bees, but the effect on managed honeybees was less clear.
"While gaps remain in our knowledge of pollinators, we have more than enough evidence to act," Prof. Imperatriz-Fonseca said.
Pests and diseases pose a special threat to managed bees, but the risk can be reduced through better disease detection and management, and regulations relating to trade and movement of bees.
Genetically modified crops are usually either tolerant to herbicides or resistant to pest insects. The former reduces the availability of weeds, which supply food for pollinators. The latter often results in lower use of insecticides and may reduce pressure on beneficial insects including pollinators. However, the sub-lethal and indirect effects of GM crops on pollinators are poorly understood and not usually accounted for in risk assessments.
Pollinators are also threatened by the decline of practices based on indigenous and local knowledge. These practices include traditional farming systems; maintenance of diverse landscapes and gardens; kinship relationships that protect specific pollinators; and cultures and languages that are connected to pollinators.
Options to safeguard pollinators
The safeguards include the promotion of sustainable agriculture, which helps to diversify the agricultural landscape and makes use of ecological processes as part of food production.
Specific options include:
- Maintaining or creating greater diversity of pollinator habitats in agricultural and urban landscapes;
- Supporting traditional practices that manage habitat patchiness, crop rotation, and coproduction between science and indigenous local knowledge;
- Education and exchange of knowledge among farmers, scientists, industry, communities, and the general public;
- Decreasing exposure of pollinators to pesticides by reducing their usage, seeking alternative forms of pest control, and adopting a range of specific application practices, including technologies to reduce pesticide drift; and
- Improving managed bee husbandry for pathogen control, coupled with better regulation of trade and use of commercial pollinators.
- A high diversity of wild pollinators contributes to increased stability in pollination, even when managed bees are present in high numbers.
- Crop yields depend on both wild and managed species.
- The western honey bee is the most widespread managed pollinator in the world, producing an estimated 1.6 million tonnes of honey annually.
- The number of beehives has increased globally over the past 50 years, but a decrease in hives has occurred in many European and North American countries.
- Climate change has led to changes in the distribution of many pollinating bumblebees and butterflies and the plants that depend upon them.
The IPBES assessment has critically evaluated an enormous body of knowledge on pollinators, pollination, and food production to ensure decision makers have access to the highest quality information. The assessment was compiled by a team of 77 experts from all over the world. The assessment cites approximately 3 000 scientific papers and includes information about practices based on indigenous and local knowledge from more than 60 locations around the world. It underwent two rounds of peer review involving experts and governments.
Featured image: European Honey Bee Touching Down by Autan (CC - Flickr)