Comparative efficacy of low-volume remotely piloted aircraft spraying with adjuvants for coffee berry borer control

ABSTRACT The coffee berry borer (Hypothenemus hampei) is one of the main pests in coffee cultivation, requiring more efficient and sustainable application technologies. This study aimed to evaluate the efficacy of different spray volumes and adjuvants for pest control using remotely piloted aircraft (RPA). The experiment was carried out in a commercial coffee plantation, in a randomized block design, with a 2 × 5 + 1 factorial arrangement: two volumes (9 and 12 L ha -1) and application of bifenthrin + acetamiprid, alone or combined with four adjuvants (mineral oil, nonionic surfactant, vegetable oil and organosilicate), in addition to a control without application, with four replications. Applications were performed with a DJI T10 RPA operating at 1.5 m height, 6.0 m s-1 speed, and 3.5 m swath width, under environmental conditions of 26-30 °C, 51-81% relative humidity, and wind speeds of 2.6-8 km h-1. Spray deposition was quantified using manganese sulfate as a tracer and analyzed by spectrophotometry. Infestation was evaluated at 7, 14, 21, and 28 days after application (DAA). The 9 L ha-1 volume provided 67-71% control at 28 DAA, superior to 12 L ha-1. The vegetable oil adjuvant increased deposition by 15-20% compared to the insecticide alone. RPA technology ensured adequate canopy penetration with a 25% reduction in spray volume compared to conventional methods. Vegetable oil and organosilicate were the most effective adjuvants. It is concluded that RPA applications with optimized low spray volumes and specific adjuvants are effective for coffee berry borer management.