Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/1/2012
Publication Date: 9/1/2012
Citation: Halbert, S., Keremane, M.L., Ramadugu, C., Lee, R.F. 2012. Incidence of huanglongbing-associated ‘Candidatus Liberibacter Asiaticus’ in Diaphorina citri (Hemiptera: Psyllidae) collected from plants for sale in Florida. Florida Entomologist. 95(3):617-624. Interpretive Summary: The Asian citrus psyllid (ACP), the insect which spreads citrus greening disease, "also known as huanglongbing (HLB)" was found in Florida, in 1998, and HLB disease was found in 2005. As part of their regulatory role in Florida, Citrus Health Response Program (CHRP) inspectors inspect citrus plants for sale in retail outlets at 30-60 day intervals. Samples from plants and insect pests which are found are forwarded to Florida Division of Plant Industry for verification and testing. We report here the results of assaying ACP which were collected as part of this survey for the presence of the bacterium associated with HLB by the use of quantitative real-time PCR. Nearly 1,200 ACP samples were tested from 2005-2009, about 9.7% of the samples tested positive for the bacterium associated with HLB. In some of the northern counties of Florida, more psyllid and plant which test positive for the bacterium associated with HLB have been found in retail stores than have been reported in the outdoor landscape. Beginning in 2009, CHRP inspectors included information when collecting samples relating to imidacloprid systemic drench (ISD) treatments which are required before plants may be moved from a nursery where the plant has been propagated to a retail store. Psyllid samples collected from ISD treated plants were assayed for the bacterium associated with HLB: about 39% of the plants with current ISD tags testing positive as compared to 55% from plants with expired or missing ISD tags.
Technical Abstract: The Asian citrus psyllid, Diaphorina citri Kuwayama, was reported for the first time in Florida in June 1998, and huanglongbing (HLB, citrus greening), vectored by D. citri, was detected in Florida for the first time in Aug 2005. In Florida, the only known HLB pathogen is ‘Candidatus Liberibacter asiaticus’ (Las). After HLB was known to be established in Florida, the psyllid vectors found in regulatory samples from plants for sale were tested for the pathogen by real-time qPCR. Approximately 1,200 regulatory samples were tested between Aug 2005 and Aug 2009. Samples came from venues in 44 of Florida's 67 counties. Most of the samples came from citrus, but about 11% came from Murraya exotica, a popular ornamental plant and close relative of citrus. Approximately 9.7% of the psyllid samples tested were positive for Las. Numbers of samples and proportion of positive samples varied by year and by county.