1-Octen-3-ol - the attractant that repels

Area of Science:

• * Chemical ecology and sensory neurobiology of insects.
• * Vector-borne disease control strategies.

Background:

• * 1-octen-3-ol is a semiochemical known to attract certain mosquito species, but its effect on the southern house mosquito (Culex quinquefasciatus) is debated.
• * Odorant receptors (ORs) in insect olfactory organs, such as maxillary palps and antennae, mediate responses to semiochemicals.
• * Enantioselectivity of odorant receptors suggests specific molecular interactions between odorants and receptors.

Purpose of the Study:

• * To identify 1-octen-3-ol-sensitive odorant receptors (ORs) in the southern house mosquito (Culex quinquefasciatus).
• * To investigate the repellent properties of 1-octen-3-ol against this mosquito species.
• * To determine the role of maxillary palps and antennae in the detection of 1-octen-3-ol repellency.

Main Methods:

• * Isolation and characterization of odorant receptors (ORs) from maxillary palps and antennae of female southern house mosquitoes.
• * In vitro and in vivo assays to test the selectivity of identified ORs towards different enantiomers of 1-octen-3-ol.
• * Surface landing and feeding assays to evaluate the repellent activity of racemic and enantiopure 1-octen-3-ol.
• * Behavioral assays using mosquitoes with ablated maxillary palps.

Main Results:

• * Identified CquiOR118b in maxillary palps with selectivity for (R)-1-octen-3-ol and CquiOR114b in antennae with preference for (S)-1-octen-3-ol.
• * Both racemic and enantiopure forms of 1-octen-3-ol demonstrated repellent activity at a 1% dose.
• * Mosquitoes with ablated maxillary palps were still repelled by 1-octen-3-ol, indicating the involvement of both maxillary palps and antennae.

Conclusions:

• * 1-octen-3-ol acts as a repellent for the southern house mosquito (Culex quinquefasciatus).
• * Both maxillary palps and antennae, housing distinct enantioselective odorant receptors (ORs), are crucial for detecting 1-octen-3-ol's repellent effects.
• * Findings contribute to understanding mosquito olfaction and developing novel control strategies using semiochemicals.