Chronic exposure to insecticides impairs honeybee optomotor behaviour

Area of Science:

• Neuroethology
• Ecotoxicology
• Insect Physiology

Background:

• Honeybees (Apis mellifera) rely on wide-field visual motion for navigation and communicate flight distances via the waggle dance.
• Seed treatment insecticides, including neonicotinoids and sulfoxaflor, negatively impact bee health, causing navigation and survival deficits.
• Neonicotinoids are known to disrupt visual motion detection in other insects, but this effect was unconfirmed in honeybees.

Purpose of the Study:

• To investigate the impact of sublethal imidacloprid and sulfoxaflor exposure on honeybee optomotor behavior.
• To determine if these insecticides disrupt wide-field motion detection in honeybees.
• To correlate behavioral changes with gene expression and neuronal effects.

Main Methods:

• Honeybees were exposed to sublethal doses of imidacloprid and sulfoxaflor.
• Optomotor behavior was assessed to measure wide-field motion detection capabilities.
• Gene expression in the brain and neuronal apoptosis were analyzed.

Main Results:

• Sublethal exposure to both imidacloprid and sulfoxaflor impaired honeybee optomotor behavior.
• Behavioral deficits correlated with altered stress and detoxification gene expression.
• Sulfoxaflor exposure caused neuronal apoptosis in the optic lobes, while imidacloprid did not.

Conclusions:

• Cholinergic insecticides like imidacloprid and sulfoxaflor disrupt the honeybee's ability to process wide-field visual motion.
• This disruption leads to impaired optomotor behaviors and likely contributes to navigation deficits.
• Findings provide a mechanism for neonicotinoid navigation effects and extend this understanding to sulfoxaflor.