Evaluation of sampling methods of Diaphorina citri Kuwayama (Hemiptera: Liviidae) in two citrus growing areas

Efficient, easy to implement and low-cost monitoring methodologies are necessary to obtain information on arthropod pest populations and to implement the most convenient and timely phytosanitary control practices. To optimize the sampling and monitoring of the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), an insect associated with the transmission of Candidatus Liberibacter asiaticus and Ca. L. americanus, which cause Huanglongbing (HLB), a disease with a great impact on citrus orchards, three methods of adult sampling (yellow sticky traps, sweep net, and stem tap) were evaluated. For immature sampling, vegetative shoots were checked. The results demonstrate that the population density at the time of sampling affects the effectiveness and sensitivity of the sampling methods. Yellow sticky traps capture more adults and are the only effective method at low psyllid densities. Stem tap and sweep net are less expensive methods; however, they do not detect adults nor correlate with the number of nymphs and eggs in vegetative shoots when adult density is low. For adults, an optimal sample size was determined for each method. For yellow sticky traps, 3 to 5 traps for a 2-hectare plot with weekly frequency are recommended. For immatures, it is recommended to estimate the percentage of infestation by inspecting 45 to 55 vegetative shoots well-distributed within a 2-hectare plot, as a practical measure for farmers and extensionists to monitor D. citri.