Nanosensor Technology for Monitoring <i>Diceraeus melacanthus</i> in Agricultural Systems

This study presents a sustainable approach for monitoring stink bugs using cantilever nanosensors functionalized with polyaniline nanocomposites doped with graphene oxide (PANI/GO) and silver nanoparticles (PANI/Ag) for the selective detection of pheromones and defensive compounds released by the brown stink bug Diceraeus melacanthus. Initially, the sensors were tested with synthetic compounds of the natural blend emitted by the pest, 4-oxo-(E)-2-hexenal, (E)-2-octenal, and tridecane, showing concentration-dependent responses with detection limits below 0.007 μg/mL, compatible with the insects’ natural emissions. The selectivity of the nanosensors was confirmed through tests against common agricultural interferents, which did not cause significant resonance frequency changes, reinforcing the sensors’ specificity. Multivariate statistical analyses, including principal component analysis, linear discriminant analysis, and receiver operating characteristic curve evaluation (area under the curve, AUC > 0.98), confirmed the sensors’ ability to accurately discriminate adult and nymph developmental stages based on their volatile emission profiles. Under seminatural conditions, the sensors accurately distinguished adults from nymphs (AUC > 0.98), with only adults showing significant responses. Increasing insect density and male–female pairing produced stronger signals, consistent with pheromone release dynamics observed in soybean environments. Together, these findings demonstrate that the developed nanomechanical sensors enable real-time, selective detection of pest-related volatiles, offering a scalable platform for integration into smart traps and automated monitoring systems in precision agriculture.