Monoterpenoid-based preparations in beehives affect learning, memory, and gene expression in the bee brain

Area of Science:

• * Environmental toxicology
• * Apiculture science
• * Neurobiology

Background:

• * Honeybee colonies face decline due to environmental contaminants.
• * Monoterpenoid preparations are used to control Varroa mites but their long-term effects are unknown.
• * Cognitive functions like learning and memory are crucial for bee survival.

Purpose of the Study:

• * To investigate the long-term effects of monoterpenoid exposure on honeybee olfactory memory.
• * To analyze the impact of monoterpenoids on gene expression related to memory pathways.
• * To understand the implications for alternative pest control strategies in apiculture.

Main Methods:

• * Olfactory conditioning of the proboscis extension reflex (PER) in honeybees.
• * Exposure of bees to monoterpenoid-based miticides in hives.
• * Measurement of gene expression levels (Amoa1, Rdl, trpl) in the bee brain.

Main Results:

• * Miticide exposure impaired PER to odors for three weeks post-treatment.
• * Both short-term and long-term olfactory memories improved months after monoterpenoid introduction.
• * Chronic exposure significantly altered gene expression of Amoa1, Rdl, and trpl, including seasonal variations.

Conclusions:

• * Monoterpenoids have complex, long-term effects on honeybee cognition and neurobiology.
• * Altered gene expression, particularly seasonal changes, may underlie memory improvements.
• * Findings offer insights into alternative bee treatments and their cognitive impacts.