Oviposition digging in the grasshopper. I. Functional anatomy and the motor programme

Area of Science:

• Neuroethology
• Insect Physiology
• Behavioral Neuroscience

Background:

• Acridid insects (grasshoppers and locusts) possess complex ovipositor appendages.
• These appendages are crucial for egg burial, egg manipulation, and capping egg pods.
• Oviposition involves cyclical movements of the ovipositor valves, driven by intrinsic musculature.

Purpose of the Study:

• To investigate the neural control underlying oviposition digging behavior in acridid insects.
• To identify the presence and location of a potential central pattern generator (CPG) for oviposition.
• To analyze the motor program for digging in isolated insect nervous systems.

Main Methods:

• Studied the ovipositor appendages and associated musculature in grasshoppers.
• Recorded muscle and nerve activity during natural and isolated oviposition behaviors.
• Utilized severed abdomens of sexually mature female grasshoppers to isolate neural activity.

Main Results:

• Isolated abdomens of female grasshoppers produced rhythmical ovipositor movements, mimicking natural digging.
• Electrical recordings from ovipositor nerves in isolated systems revealed spontaneous rhythmical bursting activity.
• This neural activity directly correlated with the digging component of the oviposition motor program.

Conclusions:

• A central pattern generator (CPG) for oviposition digging is located within the terminal abdominal ganglion of female acridids.
• The identified CPG can generate the digging motor program independently of higher brain centers.
• This finding provides insight into the neural basis of complex, rhythmic behaviors in insects.