The two-spotted spider mite (Tetranychus urticae) is a major herbivorous pest in greenhouse and open-field cucumber production (Cucumis sativus), where early infestation detection is essential for effective biological control. Within the DHYNAmite project, funded by the German Federal Ministry of Research, Technology and Space, an integrated approach combines hyperspectral imaging (HSI) for hotspot detection with targeted release of beneficial arthropods via drones. Reliable hotspot detection requires identifying infestation independently of plant developmental stage. However, plant ontogeny may influence herbivore performance and plant physiological responses to feeding. Younger plants are often assumed to exhibit higher constitutive or induced resistance, potentially delaying visible symptoms and altering spectral stress signatures. We therefore hypothesize that (1) reproductive performance differs between plant developmental stages and (2) timing and intensity of hyperspectral stress detection depend on plant age, resulting in stage-specific differences in presymptomatic detectability. This study investigates whether cucumber developmental stage affects reproductive performance of T. urticae and whether presymptomatic detection is equally reliable in young and older plants. Cucumber plants were grown under controlled climate chamber conditions and examined at two developmental stages (1 and 2 months after sowing). Three leaf categories (young, intermediate, old) were selected per plant. In a standardized micro-infestation assay, three adult females were confined to defined leaf areas using glue rings to ensure uniform feeding conditions. Mite population size, egg production, and fecal deposition were recorded daily for seven days. Hyperspectral images of infested and control leaves were acquired daily. Reflectance spectra were extracted from defined regions of interest, and spectral data were statistically analyzed to test effects of plant developmental stage, leaf position, and time. Preliminary experiments show that reproductive performance of T. urticae varies between leaf positions, indicating ontogenetic differences in host plant suitability. These findings highlight plant developmental stage as a bottom-up factor in spider mite population development. We expect reproductive output and short-term population growth to differ between plant stages, with leaf position independently modulating performance under standardized conditions. Initial hyperspectral measurements reveal detectable spectral alterations prior to visible symptoms. The completed study will determine whether these responses depend on plant age. Overall, the results will advance understanding of ontogenetically driven variation in spider mite population dynamics and provide a basis for stage-adapted monitoring and early-detection strategies.