Plant Approach-Avoidance Response in Locusts Driven by Plant Volatile Sensing at Different Ranges

Area of Science:

• Insect olfaction
• Chemical ecology
• Behavioral entomology

Background:

• Herbivorous insects rely on plant volatiles for host location.
• Antennae and maxillary palps are key olfactory organs in insects.
• Limited research exists on distance-dependent effects of specific plant volatiles on insect food selection.

Purpose of the Study:

• To investigate the role of olfactory organs in locust food selection.
• To assess the impact of plant volatile compounds at varying distances on locust behavior.
• To identify specific volatile compounds that elicit responses in locusts.

Main Methods:

• Assessed palp-opening response (POR), biting response, and selection behavior of locust nymphs (Locusta migratoria).
• Tested responses to volatile compounds from host and non-host plants at distances of 3m, 1m, and 1cm.
• Identified 30 active odorants through POR tests.

Main Results:

• Locusts were attracted to common volatiles from both host and non-host plants at 3m, with some acting as repellents.
• Responses to volatile compounds were more pronounced at 1m.
• At 1cm, locusts primarily used palps for detection, and some long-distance attractants had no short-distance biting effect.

Conclusions:

• Plant volatiles generally attract locust nymphs at long distances, with effects modulated by distance and concentration.
• Antennae and palps exhibit distinct functional roles in detecting volatiles across different distances.
• Locust food selection via olfaction involves a multi-range mechanism based on chemosensory organ sensitivity and odorant characteristics.