Spectral Characteristics of Spring Wheat Pests Using Hyperspectral Data: Diagnostics and Adaptation Features of Colouring

Abstract

Using hyperspectral imaging, the spectral characteristics of six pest species (Chorosoma schillingii, Loxostege sticticalis, Tettigonia viridissima, Chaetocnema aridula, Calliptamus italicus, and Laodelphax striatella) associated with spring wheat in northeastern Kazakhstan were investigated for the first time, complementing the few existing studies on this topic. Spectral analysis revealed how these insects reflect, transmit, and absorb light, providing insights for the future application of such data in pest recognition tasks under field conditions. The analysed species exhibited spectral responses within the 500-780 nm range. The analysed species exhibited pronounced spectral responses in the 500-780 nm range, corresponding both to peak reflectance values and the spectral window suitable for diagnostic purposes. A high reflectance coefficient was characteristic of light-coloured and smooth body surfaces, while darker, uneven, and rougher regions tended to scatter light, thereby reducing overall reflectance. Among the studied specimens, Chorosoma schillingii showed the highest reflectance due to the combination of a smooth body structure and light pigmentation, which also contributed to strong reflectance in the near-infrared region. The lowest reflectance coefficient was recorded in Chaetocnema aridula, explained by the absorption of light by dark pigments. Despite the generally light-coloured exoskeletons of most other species, their reflectance coefficient remained low due to the matte texture of the cuticle. Insect colouration not only aids in camouflage against vegetation but also serves as an adaptation to environmental conditions. Light pigmentation contributes to solar reflectance and prevents overheating, while darker colouration may offer protection against ultraviolet radiation. The variation in colouration across different body parts reflects functional adaptations to specific ecological conditions.