Insecticide resistance in Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

Abstract The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the vector of the phloem-limited plant pathogen ‘Candidatus’ Liberibacter asiaticus (CLas). CLas is the most destructive insect-transmitted plant pathogen affecting citrus production in the United States and worldwide. During the past 15 yr, insecticides spanning several modes of action have been widely implemented globally to suppress populations of D. citri. High selection pressure eventually resulted in insecticide resistance throughout Florida and in other countries, including China, Mexico, and Brazil. Some resistance ratios have been reported to reach up to 4,000-fold. To date, insecticide resistance in D. citri has been primarily associated with enhanced metabolic activity involving esterases, carboxylesterase, and P450 monooxygenase, but cases of target site insensitivity can also occur. Cuticular reorganization could also play a role in insecticide resistance in D. citri and ATP-binding cassette transporters are involved in efflux pump inhibitor-related defense/resistance against insecticides in D. citri. Rotating and mixing different classes of insecticides as well as providing temporal and spatial refuges from exposure to toxins have been employed with varying degrees of success for managing insecticide resistance for this pest. Although resistance will likely remain a major challenge, management strategies based on the coordinated use of insecticides coupled with the use of cultural and biological control tactics currently provide the best model for combating insecticide resistance in D. citri.