A study has discovered enzymes in honey bees and bumble bees that determine how sensitive they are to different neonicotinoid insecticides. By the time a pesticide 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. This new knowledge will help to make the development of insecticides, which are broadly applicable and fully compatible with bee pollinators, more efficient.

As in other organisms, toxins in bees can be broken down by enzymes called cytochrome P450s. In the joint study by Bayer, Exeter University, and Rothamsted Research, researchers carried out a comprehensive analysis of bee P450 detoxification enzymes. Researchers were able to identify one subfamily of enzymes in bees – CYP9Q – and found it was responsible for the rapid breakdown of certain neonicotinoids, such as thiacloprid. This rapid breakdown made them virtually nontoxic 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. “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.”

Nauen is confident that the required knowledge and obtained tools will promote innovation and improve Bayer’s ability to develop selective insecticides.

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

The safety of neonicotinoid insecticides to bees is a controversially discussed subject and one that, in 2013, led to a ban in the European Union on the use of three compounds on crops that are attractive to bees. In general, 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. This new knowledge will help develop insecticides that are more efficient, according to a Bayer statement.