Effects of buprofezin and diflubenzuron on various developmental stages of Asian citrus psyllid, Diaphorina citri.

BACKGROUND Diaphorina citri populations in Florida are developing resistance to commonly used neurotoxic insecticides. Alternatives to neurotoxins, such as insect growth regulators, are needed to control this season-long subtropical pest to prevent or delay development of insecticide resistance. In the present investigation, two insect growth regulators (IGRs), buprofezin and diflubenzuron, were evaluated against various developmental stages of D. citri. RESULTS The 0-1-day-old D. citri eggs were more susceptible to buprofezin and diflubenzuron than the 3-4-day-old eggs. Adult emergence was completely suppressed by treating first- or third-instar nymphs with buprofezin or diflubenzuron at 30-240 or 23-184 µg mL(-1) rates respectively. Treatment of fifth-instar nymphs with diflubenzuron at a rate of 184 µg mL(-1) and with buprofezin at 30-240 µg mL(-1) rates resulted in approximately 20 and 15-80% reductions in adult emergence respectively. The mean number of eggs per plant was reduced at 5 days after topical treatment with diflubenzuron. Mean egg hatch per plant was reduced at 5 and 6-15 days after topical treatments with buprofezin and diflubenzuron respectively. CONCLUSION Buprofezin and diflubenzuron effectively suppressed D. citri adult emergence. D. citri were more susceptible as early (first-third-instar) than late (fifth-instar) nymphs. Both IGRs inhibited egg production and egg hatch. Reduction in the number of subsequent offspring suggests reduced vertical transmission of Candidatus Liberibacter asiaticus, the pathogen thought to cause citrus greening disease. The present results indicate that both IGRs tested here should be effective tools for rotation in insecticide-based D. citri management programs.