Mosquitoes are major vectors of diseases, such as dengue, malaria, and Zika. Research on the ecological importance of mosquitoes has focused on vector–host interactions, but relatively little is known about the odor cues and neural mechanisms that lure the insects to pollinate and acquire nectar sources of nutrients from plants.

The researchers conducted pollination experiments and chemical analysis of floral odors, examined behavioral responses of Aedes mosquitoes to scents emitted by different Platanthera orchid species, and used calcium imaging to record neural responses in an olfactory brain region called the antennal lobe.

The mosquitoes both pollinated and were attracted to the Platanthera obtusata orchids, which emit a scent consisting of relatively high levels of the compound nonanal. This odor produced strong responses in an antennal lobe structure called the LC2 glomerulus, while inhibiting activity in the AM2 glomerulus.

By contrast, other Platanthera species not visited by the mosquitoes emitted scents consisting of relatively high levels of the compound lilac aldehyde. Compared with nonanal, the unattractive odors evoked the opposite pattern of neural responses in AM2 and LC2.

According to the authors, the findings illuminate the sensory underpinnings of mutualism between mosquito pollinators and nutrient-providing plants. 

https://www.pnas.org/content/early/2019/12/20/1910589117

http://sciencemission.com/site/index.php?page=news&type=view&id=publications%2Fthe-olfactory-basis-of&filter=22