Silent fields: a cocktail of pesticides is stunting bumblebee colonies across Europe, study shows

Subject: Environment

Section: Species in news

In the news:

In November 2023, the European Parliament voted against a proposal to limit the use of agricultural pesticides. These chemicals, which are crucial for protecting crops from pests, also pose a risk of contaminating air and water, potentially harming people and wildlife.
This decision contrasts with Europe’s reputation for leading in sustainability and its commitments to international environmental pledges.
Research indicates that efficient pesticide use is critical for the health of bumblebees, key pollinators for both crops and wildflowers.

Lab results v the real world:

Decades of laboratory experiments have shown that individual pesticides can be fatal to bees, and these tests are used to inform pesticide regulations.
However, these laboratory tests often examine single compounds, which doesn’t reflect the real-world scenario where bees are exposed to multiple pesticides in agricultural landscapes.
Field-based tests, which are rare, also usually focus on single compounds, despite evidence that bees encounter various pesticides in their environment, including in their food and nesting materials.
While it’s logical to think that chemicals toxic in the lab would be similarly harmful in the field, the actual impact on bees varies due to environmental persistence and various ecological factors.
Recent research has revealed that real-world exposure to multiple pesticides across landscapes significantly harms the health of bumblebees, affecting their growth, survival, and reproduction.

Colonies at risk:

Researchers placed over 300 commercially-reared bumblebee colonies at 106 sites across eight European countries and analyzed the pollen they collected for 267 pesticides.
Colonies with higher pesticide risk showed lower growth and produced fewer offspring, especially in landscapes with extensive cropland.
This underscores the importance of semi-natural habitats for pollinator populations.
The European Food Safety Authority has proposed that bumblebee colonies should not lose more than 10% of their strength due to pesticides.

Monitor pesticides like drugs:

Learning from pharmaceutical regulations, there’s a call for post-approval monitoring of pesticides under real-world conditions, in addition to pre-approval testing.
This is crucial because harmful effects of pesticides, like neonicotinoids, are often only revealed through post-approval field testing, especially on non-honeybee species.
A major initiative, with partners like The Nature Conservancy, Google, and the Brazilian state of Para, aims to promote regenerative farming practices, such as reduced tillage and lower pesticide use.

Colony Collapse Disorder (CCD):

Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee colony disappear, leaving behind a queen, plenty of food, and a few nurse bees to care for the remaining immature bees.
Several possible causes for CCD have been proposed, but no single proposal has gained widespread acceptance among the scientific community.
Suggested causes include:
- Pesticides;
- Infections with various pathogens especially those transmitted by Varroa and Acarapis mites;
- Malnutrition;
- Genetic factors;
- Immunodeficiencies;
- Loss of habitat;
- Changing beekeeping practices; or a combination of factors.
A large amount of speculation has surrounded the contributions of the neonicotinoid family of pesticides to CCD, but many collapsing apiaries show no trace of neonicotinoids.

Source: DTE