Residual effects of three neonicotinoids commonly used to control Asian citrus psyllid, Diaphorina citri

The Asiatic citrus psyllid, Diaphorina citri, Kuwayama, is widely distributed in southern Asia. It was first reported in USA during summer 1998 in Florida and spring 2001 in Texas. The damage of D. citri results sapping from foliage which causes heavy development of sooty mold on honeydew and transmission of the greening disease caused by Candidatus liberibacter. The initial and residual efficacy of three commonly used neonicotinoids to control this psyllid was evaluated in laboratory and through greenhouse trial during 72 hours and 5 weeks, respectively. The PROVADO (Imidacloprid), ACTARA (Thiamethoxam) and VENOM (Dinotefuran) were used as a foliar application at four rates (25%, 50%, 75% and 100% of recommended rate) and distillate water as a control. The greenhouse trial was designed as a completely randomized bloc with individual cages. These cages were infested every week. Regarding to laboratory bioassays, the treatments were very highly significant (P<0.0001) and showed an immediate (24 and 48h after treatment) effects of Dinotefuran on ACP adults at recommended rate with 88% and 92%, respectively. However, the mortality rates related to other neonicotinoids (Thiamethoxam and Imidacloprid) were statistically equal 72h after treatment and ranged from 74% to 100%. The results obtained in greenhouse trials showed that the neonicotinoids provide a perfect control of ACP adults during 18 days and the mortality rates were ranged from 93% to 100%. Surprisingly, Thiamethoxam was persistent for 25 days after treatment.