Insecticide application using an unmanned aerial vehicle for Diaphorina citri control in citrus orchards

The use of unmanned aerial vehicles (UAVs) combined with other methods to spray insecticides may be a useful technique for controlling Diaphorina citri Kuwayama (Hemiptera: Psyllidae) and consequently managing Huanglongbing. Therefore, this study was conducted to assess the efficacy of insecticide application using a UAV for D. citri control in citrus orchards of 1, 4 and 12 years old. In addition, spray deposition was assessed using copper as a marker. Seedlings of sweet orange were attached on the inner canopy and on the outer canopy of citrus trees before spraying insecticide or copper. An additional experiment was performed to assess the effect of 6 and 10 m spray swaths in the 4‐year‐old orchard. Ten adult psyllids were confined to each sprayed seedling. Untreated seedlings were used as a control. The first psyllid confinement was performed 4 h after spraying insecticide. The second, third and fourth confinements were performed 7, 14 and 21 days, respectively, after spraying. In general, insecticide application using a UAV resulted in psyllid mortality higher than 80% after the first and second confinements, regardless of the orchard age and seedling position on the citrus tree (inner or outer). There were no significant differences in D. citri mortality between the spray swaths assessed. Spray deposition on leaves was higher in the outer canopy than in the inner canopy of citrus trees. This study demonstrated, for the first time, the efficacy of insecticide application using a UAV for D. citri control in citrus orchards of different ages. These results broaden the prevailing perspectives on the use of UAVs as complements to ground spraying for psyllid management.