Neural correlates to flight-related density-dependent phase characteristics in locusts

Area of Science:

• Neuroethology
• Animal Behavior
• Insect Physiology

Background:

• Locust phase polymorphism involves dramatic behavioral changes driven by population density.
• Behavioral plasticity in locusts includes altered flight behavior and performance between solitary and gregarious phases.
• The neurophysiological underpinnings of these phase-specific behaviors remain largely unexplored.

Purpose of the Study:

• To investigate density-dependent differences in flight-related sensory and central neural elements in the desert locust.
• To elucidate the neural basis for the distinct flight behaviors observed in solitary versus gregarious locust phases.

Main Methods:

• Comparison of locust phase responses to controlled wind stimuli using established techniques.
• Electrophysiological recordings of neural activity in flight-related interneurons, including tritocerebral commissure giants (TCG) and tritocerebral commissure dwarf (TCD).
• Assessment of wind-induced flight initiation thresholds and spike frequency adaptation in TCG neurons.

Main Results:

• Gregarious locusts exhibited a lower threshold for wind-induced flight initiation compared to solitary locusts.
• Wind-induced spiking activity in TCG neurons was weaker in solitary locusts, with stronger spike frequency adaptation.
• Despite more wind-sensitive hairs in solitary locusts, TCG stimuli to flight motor centers were weaker.
• Increased TCD spontaneous activity in darkness was significantly stronger in gregarious locusts.

Conclusions:

• Phase-dependent differences in the activity of flight-related interneurons (TCG and TCD) correlate with behavioral phase characteristics in locusts.
• Neural processing of sensory input related to flight initiation differs significantly between solitary and gregarious locust phases.
• These findings highlight the neurophysiological mechanisms underlying behavioral plasticity in locust phase polymorphism.