Spectral Signatures of the Developmental Stages of Sphenophorus levis (Vaurie, 1978) (Coleoptera: Curculionidae) on a Natural Diet

This study investigated the spectral profiles of different developmental stages of Sphenophorus levis, possibly the most important sugarcane pest in the Southeast, Midwest, and South regions of Brazil, given its economic relevance, distribution, and management challenges in sugarcane plantations. Hyperspectral remote sensing (HRS) techniques were employed. Spectral signatures were obtained for eggs, larvae, pupae, and adults using a Pika-L sensor (range, 400–1000 nm). This made it possible to identify distinct spectral patterns for each developmental stage, allowing for the differentiation between eggs, larvae, pupae, and adults. The results indicate the presence of such distinct spectral patterns, which may suggest the potential of hyperspectral imaging for the non-destructive identification of each stage of S. levis, although further investigations are needed to validate this approach. The eggs showed high variability in reflectance, possibly related to compositional changes during embryonic development. The larval instars exhibited a decrease in reflectance with age, likely due to cuticular changes. The evaluated pupae presented spectral differences that coincidentally enabled early sex determination, while adult males and females can also be distinguished based on their reflectance profiles, with females typically showing higher overall reflectance. This spectral library provides a foundation for the determination and sexing of instars, as well as the assessment of quality patterns in this important sugarcane pest. This study highlights the integration of advanced hyperspectral imaging technologies with insect biology to enhance integrated pest management strategies and sheds light on the biological and ecological aspects of the species.