Use of EPG to examine effect of cyantraniliprole on probing behavior of potato psyllid, Bactericera cockerelli

Zebra Chip (ZC) is a new and economically important disease of potato in the United States, Mexico, Central America, and New Zealand. ZC is caused by the phloem-limited bacterium “Candidatus Liberibacter solanacearum” (Lso) transmitted to potato by the potato psyllid, Bactericera cockerelli(Šulc) (Hemiptera: Triozidae). Currently, uses of insecticide applications targeted against the potato psyllid are the only means to manage ZC. However, the ability of potato psyllid to rapidly transmit Lso once it reaches the phloem tissue represents a substantial challenge for growers in controlling this insect vector and preventing ZC transmission. In the current study, the effect of cyantraniliprole (Exirel) on potato psyllid probing behavior was assessed using the electrical penetration graph technique and compared with abamectin, an insecticide commonly used against this pest. Results showed that cyantraniliprole significantly deterred probing behavior of potato psyllid. Average duration of intercellular stylet penetration pathway on cyantraniliprole and abamectin-treated and untreated control plants was 2.59, 0.96, and 9.14 h, respectively. It took psyllids about 1.82, 1.20, and 1.73 h to reach the xylem tissue of cyantraniliprole and abamectin-treated and untreated control plants, respectively. Xylem sap ingestion duration averaged 0.53, 1.07, and 4.58 h on cyantraniliprole and abamectin-treated and untreated controls, respectively. None of the psyllids exposed to insecticide-treated plants reached the phloem tissue, except one that bypassed the xylem. The insects completely ceased probing 4.44 and 3.10 h on cyantraniliprole and abamectin-treated plants from the start of the EPG recordings, in contrast to those on untreated control plants that probed throughout the entire 24-h experiment duration. These results indicate that cyantraniliprole could help potato growers effectively manage potato psyllid and potentially reduce transmission of Lso and ZC spread.