Neuromodulation and differential learning across mosquito species.

Area of Science:

• Neuroethology
• Insect Olfaction
• Behavioral Ecology

Background:

• Mosquitoes exhibit adaptable feeding behaviors influenced by prior experiences.
• Dopamine's role in insect feeding flexibility is known, but its function in the antennal lobe (AL) is unclear.
• It is unknown if mosquitoes learn specific odors or if learning patterns are conserved across species.

Purpose of the Study:

• To investigate aversive olfactory learning in four mosquito species with varying host preferences.
• To determine if mosquitoes learn host-specific odors and if learning abilities differ between species.
• To explore the role of dopaminergic innervation in the antennal lobe (AL) in olfactory learning.

Main Methods:

• Assayed aversive olfactory learning in four mosquito species.
• Compared brain structures, specifically dopaminergic innervation patterns in the AL, across species.
• Utilized calcium imaging in the *Aedes aegypti* AL and 3D image analysis of dopaminergic innervation.

Main Results:

• Mosquito species differentially learned odors relevant to their preferred hosts.
• Human-preferring mosquitoes learned mammalian skin odors but not floral odors; a nectar-feeding species learned floral odors.
• Significant differences in AL dopaminergic innervation were observed across species, with learnable odors showing higher innervation.

Conclusions:

• Dopamine-mediated changes in the insect AL facilitate olfactory learning adaptation without altering brain structure.
• This neurochemical adaptation allows mosquitoes to adjust their olfactory circuitry for new host acquisition.
• Findings suggest an evolutionary mechanism for mosquitoes to enhance host-seeking capabilities.