Odorant-binding proteins and olfactory coding in the solitary bee Osmia cornuta

Area of Science:

• Chemical Ecology
• Insect Communication
• Pollination Biology

Background:

• Solitary bees are crucial pollinators, yet their olfactory communication remains understudied.
• Understanding bee olfaction is key to improving pollination strategies and conservation efforts.

Purpose of the Study:

• To investigate the olfactory coding mechanisms in the solitary bee Osmia cornuta.
• To identify specific volatile compounds involved in chemical communication within O. cornuta.
• To characterize the olfactory receptor repertoire and binding proteins in O. cornuta antennae.

Main Methods:

• Gas chromatography-mass spectrometry (GC-MS) for volatile compound identification.
• Antennal transcriptome analysis to identify olfactory genes (ORs, OBPs, CSPs, SNMPs).
• Heterologous expression and in vitro binding assays for OBP characterization.

Main Results:

• Identified female-specific (E)-geranyl acetone and male-specific 2-hexyl-1,3-dioxolane.
• Quantified 48 olfactory receptors (ORs), 6 odorant-binding proteins (OBPs), 5 chemosensory proteins (CSPs), and 1 sensory neuron membrane protein (SNMP) in O. cornuta antennae.
• Discovered a lower number of ORs and OBPs compared to honeybees, with a notable absence of C-minus OBPs.
• Expressed OBPs showed binding affinities for common plant odorants and bee-derived volatiles.

Conclusions:

• Osmia cornuta possesses a distinct olfactory system with fewer olfactory receptors and binding proteins than honeybees.
• The identified sex-specific volatiles likely play a role in O. cornuta mating and communication.
• Further research into O. cornuta olfaction can enhance understanding of solitary bee pollination and conservation.