Visual Aggregation Sensitivity of the Locusta migratoria manilensis Under Partially Polarized Light in Greenhouses

Locusta migratoria manilensis causes frequent locust outbreaks in China. This study addresses technical barriers to developing monitoring and control methods based on optical traps. We examined the synergistic effects of spectral light and linear polarized light, and their relationship to visual aggregation under partially polarized illumination. Results showed that the coupling of unpolarized and polarized components within partially polarized light determines the effectiveness of polarized spectral vector illumination on locust aggregation sensitivity. Spectral characteristics modulate polarization-dependent visual sensitivity and affect synergy between spectral and polarized light. The induction of aggregation depended on both the spectral properties of partially polarized light and the illumination parameters. Among the tested conditions, unpolarized violet light combined with linearly polarized orange light at a 270° vector angle produced the strongest time-dependent effect, followed by unpolarized orange light combined with linearly polarized violet light at 0°. The combined stimulation of spectral and polarized-light-triggered aggregation through polarization-enhanced polarotaxis and spectrum-driven phototaxis. This behavior appears to result from nonlinear regulation between unpolarized and polarized components, which increases directional sensitivity for orientation. These findings show that partially polarized light can effectively trap locusts, promote aggregation, and interfere with navigation, providing a basis for improved optical control strategies.