Cross-modal sensory compensation increases mosquito attraction to humans

Area of Science:

• Neuroethology
• Sensory Biology
• Insect Behavior

Background:

• Sensory compensation is a phenomenon where the loss of one sense enhances another.
• Female Aedes aegypti mosquitoes rely on olfactory cues for host-seeking.
• Odorant receptor co-receptor (Orco) plays a crucial role in olfaction.

Purpose of the Study:

• To investigate a novel mechanism of sensory compensation in female Aedes aegypti mosquitoes.
• To understand how olfactory sensory loss affects other sensory modalities in host-seeking behavior.

Main Methods:

• Utilized Orco mutants to assess changes in sensory perception.
• Examined heat-evoked neuronal activity in foreleg sensory neurons.
• Investigated the role of Ir140, an ionotropic receptor, in sensory compensation using double mutants.

Main Results:

• Orco mutants exhibited heightened attraction to human skin temperature and increased heat-evoked neuronal activity.
• Ir140 expression was found to be up-regulated in the legs of Orco mutants.
• Ir140, Orco double mutants lacked the enhanced heat-seeking behavior observed in Orco single mutants.

Conclusions:

• Up-regulation of Ir140 in the foreleg is a key mechanism for sensory compensation in Orco mutant mosquitoes.
• This compensation involves an indirect, long-range mechanism due to sparse Orco expression in legs.
• Female Aedes aegypti mosquitoes maintain effective host-seeking despite olfactory loss by enhancing thermal attraction.