Not all neonicotinoid insecticides have negative effects on bees, according to researchers at Sweden's Lund University and the Swedish University of Agricultural Sciences. The new study indicates that the use of certain neonicotinoids could benefit bumblebees and pollination.
In a field study, researchers Maj Rundlöf with Lund University and Ola Lundin with the Swedish University of Agricultural Sciences found that the neonicotinoid thiacloprid does not have any detectable negative impact on bumblebees, according to an announcement from Lund University.
When the insecticide was used on red clover fields, insect pests were successfully controlled while, at the same time, more bumblebees came to visit and pollinated the crop, the researchers said.
The study also showed that the bumblebee colonies close to the thiacloprid-treated red clover fields grew larger compared to bumblebee colonies in landscapes without red clover fields, the researchers added.
The research, therefore, indicates that certain neonicotinoids that are still permitted in the European Union could actually benefit the bumblebees rather than harming them. The risk of direct impact on the bumblebees is low, while the thiacloprid protects the flowering fields where the bumblebees feed.
"Our study shows that neonicotinoids should not be treated as a homogenous group when evaluating the environmental risks of insecticides. There are pest management solutions that do not detectably harm bumblebees," Rundlöf said.
Since Dec. 1, 2013, the EU has banned the use of three neonicotinoids on flowering crops: clothianidin, imidacloprid and thiamethoxam; the reason for the ban is that the substances have been identified as harmful to bees, the announcement said. In spring 2018, the EU tightened the ban, and now insecticides containing any of the three substances may be used only in permanent greenhouses.
If the recently studied neonicotinoid thiacloprid meets the same fate, it could lead to negative consequences for bumblebees, according to Rundlöf.
"If this effective pest management solution was to disappear from the market without there being an adequate alternative, farmers would most likely grow less red clover seed, and this would mean less food for the bumblebees," she said.
Thiacloprid is on the EU list of candidates for substitution, meaning it could be banned in the near future, the announcement said. This is because it has been found to have endocrine-disruptive properties. However, Rundlöf hopes future studies can build on the findings from this research.
"Our study nuances the view on neonicotinoids a little. The results open up to there being other alternatives within the neonicotinoid group that are not suspected to have endocrine-disruptive properties. These could be alternatives for efficient pest regulation that are still acceptable for pollinators as well as humans," she concluded.