Different Bee Species in Ireland Show Different Pesticide Exposure Patterns

Bees are vital pollinators of many crops and wild plants, providing essential ecosystem services and supporting food security and biodiversity.

However, bees are facing multiple threats, such as habitat loss, climate change, diseases, parasites, and pesticides.

Pesticides are chemicals that are used to control pests or weeds, but they can also harm non-target organisms, such as bees. It can affect bees directly by contact or ingestion, or indirectly by contaminating their food sources, such as pollen and nectar.

What are neonicotinoids and how do they affect bees?

(Photo : Dan Kitwood/Getty Images)

Neonicotinoids are a class of systemic insecticides that act on the nervous system of insects. They are widely used in agriculture and horticulture, as well as in veterinary and household products.

Neonicotinoids can be applied as seed coatings, soil drenches, foliar sprays, or granules. They can be taken up by plants and translocated to all parts of the plant, including the flowers, where they can be found in pollen and nectar.

Neonicotinoids have been linked to the decline of honey bees and other pollinators, with evidence suggesting that the pesticides harm baby bee brain development, weaken immune systems, and can leave bees unable to fly.

It can also impair bees' learning and memory abilities, which are crucial for foraging and navigation.

Moreover, neonicotinoids can affect bees' social behavior, such as communication, reproduction, and colony cohesion.

Even at sublethal doses, neonicotinoids can have chronic and cumulative effects on bees over time.

Also Read: 'Pollen Thief' Bees Could Threaten Plants

What are the findings of the new study on pesticides in bee pollen?

A new study by researchers from Trinity College Dublin and Dublin City University evaluated pesticide residues in crop pollen at 12 sites in Ireland and in pollen collected from honey bees and bumble bees from the same sites.

They published their findings in the journal Science of the Total Environment.

The study found that most pesticides detected had not been applied recently to the sampled fields, suggesting that some chemicals may persist for a long time in the soil or come from other sources within the foraging range of bees.

The study also found that crop pollen was only contaminated with fungicides; honey bee pollen was mostly contaminated with fungicides; bumble bee pollen was mostly by neonicotinoid insecticides.

The highest number of compounds and most pesticide detections were in bumble bee pollen.

All five neonicotinoid insecticides assessed were found in bumble bee pollen, even though these had not been applied recently to the sampled fields.

The study concluded that these results raise significant concerns about the potential widespread exposure to multiple pesticides for different bee species.

Using honey bees as a reference for understanding the exposure to different pesticides cannot give a complete picture, as different bee species may be exposed differently to pesticides, according to the study.

Researchers highlighted the need for more comprehensive monitoring of pesticide residues in bee pollen and other matrices to assess the risks to pollinator health.

Pesticides in bee pollen pose a serious threat to pollination and biodiversity. Neonicotinoids are especially harmful to bees, as they can affect their nervous system, cognition, behavior, and survival.

Since different species of bees are extremely important for food security and the continuous harmony of the ecosystem, scientists are conducting various studies to help improve bees' lives and prevent them from going extinct.