Breakthrough
Could Aid Development
of Bee-Friendly Pesticides
Efforts to create pesticides that are not toxic to bees have
been boosted by a scientific breakthrough.
of Bee-Friendly Pesticides
Efforts to create pesticides that are not toxic to bees have
been boosted by a scientific breakthrough.
University of Exeter –
March 22, 2018 -- A joint study by the University of Exeter
The potential impact of neonicotinoids on bee health is a
subject of intensive research and considerable controversy, with the European
Union having restricted three compounds on crops that are attractive to bees in
2013.
However, both honeybees and bumblebees exhibit profound
differences in their sensitivity to different members of this insecticide class.
The researchers aimed to understand why this is, in order to aid the
development of pesticides that are non-toxic to them.
Just as in other organisms, toxins in bees can be broken
down by enzymes called cytochrome P450s. The study identified one subfamily of
these enzymes in bees – CYP9Q – and found it was responsible for the rapid
breakdown of certain neonicotinoids.
“Identifying these key enzymes provides valuable tools to
screen new pesticides early in their development to see if bees can break them
down,” said Professor
Chris Bass, who led the team at the University of Exeter
“It can take a decade and $260 million to develop a
single pesticide, so this knowledge can help us avoid wasting time and money on
pesticides that will end up with substantial use restrictions due to intrinsic
bee toxicity.”
Dr Ralf Nauen, insect toxicologist and lead investigator
of the study at Bayer added: “Knowing the mechanisms contributing to inherent
tolerance helps us and regulators to better understand why certain insecticides
have a high margin of safety to bees”.
“The knowledge from our study can also be used to predict
and prevent potential harmful effects that result from inadvertently blocking
these key defence systems, for instance by different pesticides (such as
certain fungicides) that may be applied in combination with insecticides.”
Professor Lin Field, Head of the Department of
Biointeractions and Crop Protection at Rothamsted Research added: “Some
neonicotinoids are intrinsically highly toxic to bees but others have very low
acute toxicity, but in public debate they tend to get tarred with the same
brush.
“Each insecticide needs to be considered on its own risks
and merits, not just its name.”
The researchers carried out the most comprehensive
analysis of bee P450 detoxification enzymes ever attempted.
Comparing the effects of two neonicotinoids, they found
bees metabolise thiacloprid very efficiently, while they metabolise
imidacloprid much less efficiently.
Although previous work had suggested rate of metabolism
might explain why bees react differently to different neonicotinoids, the
specific genes or enzymes were unknown until now.
The research was part funded by Bayer, which is a
manufacturer of neonicotinoid insecticides.
The paper, published in the journal Current Biology,
is entitled: “Unravelling the molecular determinants of bee sensitivity to
neonicotinoid insecticides.”
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