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BeeLife at the Complementary Hearing on Pesticides - Event at the European Parliament

Updated: Jan 6, 2022

An overview of the risk posed by neonicotinoids and others economic and variable alternatives.

On Wednesday 5 September 2018, the political party The Greens organised a hearing on Pesticides and their effects on human health and the environment at the European Parliament. BeeLife’s Scientific advisor, Noa Simon Delso, was a guest speaker. She presented the state of the art on the risks that neonicotinoids (and fipronil) pose to biodiversity. The presentation also focused on the Worldwide integrated assessment of the impact of systemic pesticides on biodiversity and ecosystem.

Greens Complementary Hearing on Pesticides, 05 september 2018

Dr. Noa Simón Delso explained the development of the first world-wide meta-analysis on the effects of neonicotinoids and fipronil in the environment. Several scientists, with different backgrounds, collaborated on the research. Thanks to such collaboration, it was possible to measure the impact of these substances on ecosystems and the alternatives that caused to reduce negative impacts on the environment. The main findings are:

  • The clear evidence of harm - sufficient to trigger regulatory action

  • Neonics persist for months/years, counting that they are systemic and water soluble

  • Toxicity is increased by the duration of exposure

  • Effects of exposure range from acute to chronic

  • Environmental Impacts of Pesticides, including Mitigation Measures at Member State Level.

In the case of pollinating insects and mainly in the case of bees, there are high levels of exposure through plants, water, soil and the air, as may be seen in the following infographic.

Levels of exposure and ecotoxicological effect of neonicotinoids in insects

After the study, researchers concluded that the effects of neonicotinoids were stronger when exposed together with other insecticides than when exposed alone, showing that bees do not die after exposure to them but they develop many physical and perception problems. Findings reveal a strong impact on the queen’s reproductive success. Besides, bees develop problems to return to their hive.

Even though results vary depending on several factors, including the bee species, the intended use for the pesticide and the different routes of exposure through pollen and nectar residues prove to be harmful to non-targeted insects. Due to the dispersion of the dust during the sowing of treated seeds or through the consumption of Water, the harm of these pesticides also leaps from the targeted location.


These pesticides have been found to have the following sub-lethal effects:

Behavioural modifications (learning, memory, response to stimuli, etc.)

Morphological modifications (glands or organs)

Physiological modifications (metabolic, respiratory rhythm, etc.)

Reproduction modifications (of queens and drones)

Problems with activity, locomotion, homing flight Interactions with pathogens making bees more sensitive to develop clinical signs of disease


The following lethal effects have been identified in honeybees:

  • Acute toxicity (after 1 contact) – extremely high (between 7000 and 11000 higher than DDT)

  • Delayed toxicity – contaminated colonies do not show visible effects until some weeks or months later

  • Chronic toxicity at even lower doses, but during longer exposure time (e.g. 10 days)

  • Atypical dose-effect relationship with a high toxicity at very low and very high doses

  • Synergistic effects with other pesticides

From all the above, Dr. Noa Simón Delso concluded that the present scale of use is not sustainable, particularly when alternatives exist and are economically viable. The continued use of such substances can only accelerate global decline of important invertebrates. Viable alternatives for reducing risks are available and would greatly benefit the environment, farmers and beekeepers.

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