Aerodynamic Design and Laboratory Evaluation of a Variable Cross-Section Wind-Suction Channel for Capturing Small Agricultural Pests

Physical control technology as an alternative to chemical pesticides is of great significance for modern sustainable agriculture. However, small pests such as tea green leafhoppers and tea thrips possess sensitive aerodynamic receptors that easily perceive disturbances generated by suction airflow and initiate stress-induced escape behavior. The current bottleneck in the state of the art is that conventional straight tube capture devices generate severe airflow pulsations and turbulence near the intake which act as alarm signals causing pests to escape before entering the effective capture zone. To resolve this trade-off, this study developed and validated a variable cross-section wind-suction channel based on the principle of biological behavioral suppression. This design incorporates a three-stage functional structure consisting of a flow-stabilizing intake section a guided acceleration section and a high negative-pressure throat to achieve a synergistic balance between low disturbance induction and strong aerodynamic confinement. Numerical simulations and prototype experiments show that this design establishes a stable rectified environment at the intake with relative wind speed deviations within 5%. Under controlled laboratory conditions, the average capture rate for target pests exceeded 85% within an effective operating radius of 20 cm. Comparative biological validation further confirms that the capture efficiency of this design is improved by more than 32 percentage points compared with a conventional straight-tube benchmark device. Furthermore, the critical stress-response distance was reduced by approximately 50%, significantly enhancing the concealment of the capture process. These findings elucidate the critical role of channel geometry in resolving the conflict between suction intensity and environmental disturbance providing a theoretical foundation and technical support for the development of high efficiency and precision plant protection equipment.