# Sub-lethal imidacloprid exposure leads to presynaptic and postsynaptic alterations

## TL;DR

Exposure to low levels of the pesticide imidacloprid affects the nervous systems of honey bees and nematodes by altering synaptic structures and gene expression.

## Contribution

The study demonstrates sub-lethal imidacloprid effects on synaptic structures in two off-target organisms using comparative neuroscience methods.

## Key findings

- Honey bees exposed to imidacloprid showed reduced microglomeruli density in their brains.
- Nematodes exposed to imidacloprid exhibited decreased expression of both presynaptic and postsynaptic cholinergic structures.
- Field-relevant concentrations of imidacloprid impact the nervous systems of non-target species.

## Abstract

Pesticides are commonly used in agriculture to mitigate a wide array of pests. Imidacloprid, the most frequently used neonicotinoid pesticide, has been reported to affect cholinergic signaling of off-target organisms, such as honey bees and nematodes. Taking comparative neuroscience approaches, we exposed both organisms to field-relevant sub-lethal doses of imidacloprid. In the honey bee brain, we examined microglomeruli (synaptic structures of the mushroom bodies) using synapsin immunostaining. There was a decreased density of microglomeruli following one week of imidacloprid exposure. Furthermore, to take a separate look at either side of cholinergic synapse, we used two distinct strains of transgenic nematodes labeling either presynaptic or postsynaptic cholinergic structures. Following 48 hours of exposure, we found decreased expression in both strains. These results indicate that concentrations of imidacloprid commonly occurring in the field alter the nervous systems of off-target organisms.