Monitoring of insecticide resistance in Diaphorina citri Kuwayama (Hemiptera: Psyllidae) from citrus groves of Punjab,Pakistan

The Asian citrus psyllid, Diaphorina citri Kuwayama being a vector of huanglongbing (HLB), citrus greening disease is the most destructive pest of citrus and the management of D. citri is crucial for successful control of HLB. We evaluated adult populations of D. citri from twelve districts of Punjab, Pakistan for resistance to seven different insecticides. Different levels of resistance ratios were observed for all insecticides (chlorpyrifos, bifenthrin, imidacloprid, acetamiprid, thiamethoxam, nitenpyram and chlorfenapyr). Field collected populations of D. citri were highly resistant to imidacloprid as compared to the susceptible population. The resistance ratios were in range of 236.6–759.5, 55.5–212.8, 13.1–46.4, 31.4–216.7, 8.6–89.4-fold for imidacloprid, acetamiprid, chlorfenapyr, nitenpyram, and thiamethoxam, respectively and 39.8–107.1 and 32.7–124.5-fold in case of conventional insecticides i.e., bifenthrin and chlorpyrifos, respectively. Nitenpyram and thiamethoxam, with no or very low resistance should be used in combination or in rotation with other pest management tactics for managing resistance in D. citri. The correlation analysis of the LC₅₀'s of insecticides showing positive and negative correlations among different insecticides in all tested populations, suggests mechanism of cross-resistance. Imidacloprid showed a positive correlation with acetamaprid, but a negative correlation with thiamethoxam from the neonicotenoid group, while the resistance to chlorfenpyr positively correlated with chlorpyrifos and bifenthrin in the pyrethroid group. Multiple resistance mechanisms could be the reason behind the development of such a high resistance in the D. citri.