Odor-based real-time detection of maize plants under attack by pests: proof of concept

Rapid detection of crop pests and diseases can enable timely, targeted interventions, and help reduce pesticide use. Plants under biotic stress are known to rapidly emit characteristic blends of volatile compounds that could potentially serve as fast and attacker-specific cues for precise pest monitoring. Here, we evaluated the feasibility of this approach using two complementary, state-of-the-art sensing technologies: a handheld nanomechanical membrane-based sensor array and chemical ionization time-of-flight mass spectrometry. Under laboratory conditions, with enclosed headspace sampling, both technologies readily distinguished undamaged maize plants from plants infested by caterpillars or infected with a fungal pathogen. Under semi-controlled outdoor open-air conditions, where volatile concentrations were strongly diluted, the membrane-based sensor no longer retained discriminatory power, whereas mass spectrometry predicted herbivory status with high accuracy using one-second measurements. Finally, a preliminary one-day field trial indicated that a compact, field-deployable, real-time mass spectrometer may discriminate between undamaged maize plants and plants subjected to simulated herbivory using spectral information averaged over 60-s measurement periods. Together, these results provide initial evidence for the potential of real-time mass spectrometry as a promising tool for crop monitoring to detect plants under attack by pests. However, further field validations are needed and several critical challenges remain to be addressed before translation to practical field applications.