A new study finds that enzymes in honey bees and bumble bees determine how sensitive they are to different neonicotinoid insecticides.

The joint study by Exeter University, Rothamsted Research and Bayer found that certain neonicotinoids are more toxic to bees than others.

As in other organisms, toxins in bees can be broken down by enzymes called cytochrome P450s. The researchers carried out the most comprehensive analysis of bee P450 detoxification enzymes ever conducted. The study identified one subfamily of these enzymes in bees - CYP9Q - and found it was responsible for the rapid breakdown of certain neonicotinoids, such as thiacloprid, making them virtually non-toxic to bees. Bayer is confident that this knowledge will enable the company to design further bee-friendly insecticides in an even more targeted way, using relatively simple methods (in vitro) at an early stage of a product’s development.

"Identifying the mechanisms that contribute to inherent tolerance helps us, and regulators, to better understand why certain insecticides have a high margin of safety in bees," said Dr. Ralf Nauen, an insect toxicologist at Bayer and lead investigator of the study. "The knowledge from our study can also be used to predict and prevent potential harmful effects that result from inadvertently blocking these key defense systems, for instance, by different compounds with synergistic effects in tank mixtures." 

This knowledge is valuable at a time when it has become increasingly difficult to register new pesticides, particularly in Europe. 

What does the science say? In general, that 19 of the top 20 insecticides are intrinsically highly toxic. However, even the different compounds in the class of neonicotinoids vary in terms of their toxicity.

By the time it reaches the market, each crop protection product will have cost, on average, $286 million and required 11 years of research and development to ensure the highest safety and efficacy standards.

Source: Bayer