An antennal-specific OBP mediates bait odorant perception in fire ants

Area of Science:

• Entomology
• Molecular Biology
• Chemical Ecology

Background:

• Odorant binding proteins (OBPs) mediate external stimuli to neuron activation.
• The invasive ant Solenopsis invicta uses ham sausage as an effective field monitoring bait.
• Chemoreceptors for bait odorant perception in S. invicta remain uncharacterized.

Purpose of the Study:

• Investigate the role of SiOBP2, an antenna-specific OBP in S. invicta, in detecting bait odorants.
• Characterize the binding properties of SiOBP2 with key bait odorants.
• Determine the functional significance of SiOBP2 in S. invicta's olfactory responses and foraging behavior.

Main Methods:

• SiOBP2 expression analysis in S. invicta antennae.
• In vitro binding assays to assess SiOBP2 affinity for bait odorants (e.g., 3-mercapto-2-butanone, furfuryl mercaptan).
• SiOBP2 knockdown via RNA interference, followed by electroantennogram (EAG) and behavioral assays.

Main Results:

• SiOBP2 is specifically expressed in sensillum basiconca of S. invicta antennae.
• SiOBP2 exhibits strong binding affinity and diverse binding mechanisms with 3-mercapto-2-butanone and furfuryl mercaptan.
• SiOBP2 knockdown abolished EAG and behavioral responses to odorants, impaired neuron signaling, and reduced bait-searching efficiency.

Conclusions:

• SiOBP2 is indispensable for S. invicta's perception of ham sausage odorants.
• Sensillum basiconca are specifically tuned to 3-mercapto-2-butanone and furfuryl mercaptan.
• SiOBP2 represents a promising molecular target for developing novel S. invicta attractants.