Effects of Soil-applied Imidacloprid on Asian Citrus Psyllid (Hemiptera: Psyllidae) Feeding Behavior

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is one of the most important pests of citrus (Citrus spp.) because of its status as a vector of Candidatus Liberibacter asiaticus (Las), the bacterium associated with citrus greening disease. The use of insecticides for vector control is the primary method of managing the spread of this pathogen. Imidacloprid is an insecticide commonly applied to the root zone of young citrus trees to provide systemic protection from pests. The effects of imidacloprid on feeding behavior of D. citri have not been studied in much detail. The purpose of this study was to examine the effects of imidacloprid application on feeding behavior of D. citri and to determine whether use of this systemic insecticide could have any effect on pathogen transmission by D. citri. A direct current electrical penetration graph monitor was used to record D. citri feeding behaviors for 12-h periods on mature and young leaves of imidacloprid-treated and -untreated citrus seedlings. Overall, compared with untreated plants, the feeding behavior of D. citri was disrupted on imidacloprid-treated plants via reduction in the number of probes, as well as durations of average probes, initial stylet contact with phloem, phloem salivation, and phloem ingestion. The results of this study demonstrate that soil applications of imidacloprid can reduce the probability of citrus plants becoming inoculated with Las through a reduction in the number and duration of phloem salivation events by D. citri. Furthermore, Las acquisition from infected citrus is greatly reduced as a result of decreased phloem ingestion by D. citri on imidacloprid-treated plants.