Unmanned Aerial Vehicle-Based Techniques for Monitoring and Prevention of Invasive Apple Snails ( Pomacea canaliculata ) in Rice Paddy Fields

The destructive impact of invasive apple snail ( Pomacea canaliculata ) on young rice seedlings has garnered global attention, particularly in warm regions where rice production occurs. The preventative application of insecticide, particularly in areas with young rice seedlings and water depths exceeding 4 cm, has proven effective in mitigating this damage. In line with this recommendation, our study investigates the efficacy of site-specific drone-based insecticide applications to mitigate snail damage in rice paddies. These site-specific drone applications were strategically executed as directed by a highly accurate prescription map indicating the required insecticide quantity at specific locations. The prescription map was automatically generated through an advanced data processing program that used the aerial images acquired by a Real-Time Kinematic (RTK)-Unmanned Aerial Vehicle (UAV) as the input. Criteria were established to select the treatment locations; a value of below 4 cm from the top 95% percentile in the histogram of ground elevation data was used as a threshold to identify areas with a high-density of snail damage. The results demonstrated reductions in both the rates of rice damage and chemical usage following site-specific drone applications compared with the control fields. The findings in this study contribute to the advancement of effective site-specific pest control in precision agriculture.