Kaikki aineistot
Lisää
Abstract Background: Intensive agriculture, including pesticides, is one of the many reasons for pollinator decline. The EU legislation on plant protection products (hereon pesticides) demands that the risks of active substances and their use in pesticide products are assessed for bees. However, the risk assessment is not always sufficient as shown, for example, in the case of the fungicide Amistar. The fungicide has been shown to cause lethal and sublethal effects on bumblebees at levels that, according to the EU risk assessment, do not require risk mitigation measures to protect bees. In order to understand the effects of chronic Amistar exposure on bumblebees, we studied whether 5 days of oral exposure to 0.015 μl Amistar (3.75 μg azoxystrobin/day) impairs bumblebees’ learning and memory performance in the 10-colour discrimination task. Results: Chronic Amistar treatment did not impair the learning of the bees, but a statistically non-significant negative trend was observed in memory retention between the final learning bout and the subsequent memory test. Conclusions: The results of our study suggest that chronic sublethal exposure to Amistar fungicide did not significantly impair the learning ability of bumblebees. However, there was a trend towards impaired memory retention, although this was not statistically significant. These findings provide further support for the hypothesis that Amistar may have a negative effect on bee cognitive performance. It is important to continue studying the effects of widely used pesticides on pollinators, as their decline is a complex issue with multiple contributing factors. Understanding the effects of different pesticide residue levels on bumblebees can inform policymakers in making more sustainable pesticide legislation and help protect pollinators.
Abstract Pollinator decline is a grave challenge worldwide. One of the main culprits for this decline is the widespread use of, and pollinators’ chronic exposure to, agrochemicals. Here, we examined the effect of a field-realistic dose of the world’s most commonly used pesticide, glyphosate-based herbicide (GBH), on bumblebee cognition. We experimentally tested bumblebee (Bombus terrestris) color and scent discrimination using acute GBH exposure, approximating a field-realistic dose from a day’s foraging in a patch recently sprayed with GBH. In a 10-color discrimination experiment with five learning bouts, GBH treated bumblebees’ learning rate fell to zero by third learning bout, whereas the control bees increased their performance in the last two bouts. In the memory test, the GBH treated bumblebees performed to near chance level, indicating that they had lost everything they had learned during the learning bouts, while the control bees were performing close to the level in their last learning bout. However, GBH did not affect bees’ learning in a 2-color or 10-odor discrimination experiment, which suggests that the impact is limited to fine color learning and does not necessarily generalize to less specific tasks or other modalities. These results indicate that the widely used pesticide damages bumblebees’ fine-color discrimination, which is essential to the pollinator’s individual success and to colony fitness in complex foraging environments. Hence, our study suggests that acute sublethal exposure to GBH poses a greater threat to pollination-based ecosystem services than previously thought, and that tests for learning and memory should be integrated into pesticide risk assessment.