Locust and grasshopper plagues pose a serious threat to crop production in many areas worldwide. However, there is a lack of effective, quick-acting methods to control such outbreaks. Methods exploiting the phototactic response of these insects are receiving increasing attention. The current study investigated the effect of linearly polarized and unpolarized light on locust phototactic and polarotactic responses, in particular the function of their dorsal rim area (DRA) and non-DRA visual fields. The results showed that the polarotactic function weight of DRA vision was stimulated by linearly polarized ultraviolet (UV) and violet light, the phototactic function weight was induced by blue, green, and orange light, and under linearly polarized light, the functional effect of DRA vision was strongest in response to linearly polarized violet light. Moreover, the locust visual response effect was related to spectral light attributes, with the linear polarization effect intensifying in response to the short-range vision sensitivity of non-DRA visual fields, whereas DRA vision regulated the short-range sensitivity of compound eye vision. When illumination increased, the synergistic enhancement effects of linearly polarized ultraviolet and violet light were significant, whereas the visual sensitivity was restricted significantly by linearly polarized blue, green, or orange light. Thus, non-DRA vision determined, while DRA vision enhanced, the phototactic response sensitivity, whereas, in linearly polarized UV or violet light, non-DRA vision determined, while DRA vision enhanced, the visual trend and polarotaxic aggregation sensitivity, with opposite effects in linearly polarized blue, green, or orange light. When illumination increased, there was a driving effect caused by linearly polarized violet light on non-DRA vision, whereas at short-wave lengths, the control effect induced by linearly polarized orange light was optimal; however, the photo-induced effect of linearly polarized violet light and the visual distance control effect of linearly polarized orange light were optimal. These results provide theoretical support for the photo-induced mechanism of the locust visual response effect and for the development of linearly polarized light sources for the environmentally friendly prevention and control of locust populations. Keywords: Locusta migratoria, linearly polarized light, spectral light, visual response, DRA and non-DRA vision DOI: 10.25165/j.ijabe.20231603.7959 Citation: Zou S G, Liu T, Ma Y C, Zhang P C Liu Q H. Influences of DRA and non-DRA vision on visual responses of locusts stimulated by linearly polarized and unpolarized lights. Int J Agric & Biol Eng, 2023; 16(3): 15–22.

Synergistic influence of the capture effect of western flower thrips (Frankliniella occidentalis) induced by proportional yellow-green light in the greenhouse

Peculiar influence of linearly polarized spectrum illumination patterns onthe sensitivity characteristics of locust response to polarized light

Influences of linearly polarized light and linearly polarized vectors on the visual selection sensitivity and polartactic response effect of locusts

This study investigated the effects of polarized and spectral light interactions on locust polarotaxic behavior and elucidated the regulatory mechanisms of polarized and spectral lights. Locust visual response effect was investigated using a combined light source system comprising linear detection polarization violet light with various spectrum lights and a response device to explore the interaction mechanism of polarized and spectral lights on locust visual sensitivity characteristics and the specific sensitivity of locust phototaxis and polartaxis. Results indicated that the polarized vector sensitivity of locusts was related to combined light intensity, showing high visual response sensitivity at 0° and 180° under 1000 lx, whereas under rated illumination (150 mW/cm 2), the coupled spectrum attributes induced changes in the locusts' sensitive vectors. UV, violet, and blue lights enhanced the sensitivity at 90° and 270°, and green and orange lights did so at 0° and 180°. Moreover, UV and violet lights enhanced the aggregation and trend sensitivity at 210° and 30°, blue, green and orange lights induced high sensitivity at 0° and 180°. Under increasing illumination, the enhanced effect of light intensity on aggregation sensitivity under blue, green, and orange spectra and on trend sensitivity under orange spectra at 90° and 270° were highly pronounced because of the interaction between heterogeneous spectrum illumination and linear detection polarization vector illumination. Meanwhile, the spectral attribute determined the locust visual response effect, which was affected by the linear detection polarization vector. When illumination increased to rated illumination, coupled light intensity induced a specific vector sensitivity related to optical distance, showing the strongest response sensitivity to 180° under orange spectra and the strongest aggregation and trend sensitivity to 210° under violet spectra due to the interplay of polarization degree, coupling light intensity, and specific vision sensitivity caused by partially polarized light. Then, the locust visual response effect was improved by utilizing the enhancement effect of polarized violet light coupled with violet light at a close range and the inductive effect of polarized violet light coupled with orange light at a long distance, which provide theoretical support for understanding locust polarotactic orientation mechanisms, facilitate the development of polarization induced light sources for attracting locusts.

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.