Location: Subtropical Insects and Horticulture Research
Project Number: 6034-22320-004-021-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Feb 1, 2016
End Date: Jan 31, 2020
Objective:
Screen for populations of Asian citrus psyllid that segregate genetically for the ability to transmit the pathogen responsible for citrus greening disease.
Approach:
Colonies of potentially good or poor vectors will be established using an individual adult female Asian citrus psyllid (ACP) paired with a single male. Each pair of Asian citrus psyllid will be collected in the wild from a specific source (location, host plant species), introduced onto a potted orange jasmine plant in a cage maintained in a greenhouse, and allowed to reproduce. Additional pairs of adult Asian citrus psyllid will be collected and treated similarly, collectively establishing a set of isofemale lines. Each line will be screened to ensure the psyllids are free of the citrus greening pathogen Candidatus Liberibacter asiaticus (CLas) and if the pathogen is present the line will be eliminated, as these isofemale lines need to be free of Candidatus Liberibacter asiaticus. We intend to subject 45 disease-free isofemale lines to the following procedures to gauge their efficiency at acquiring and transmitting Candidatus Liberibacter asiaticus.
Adult progeny from each isofemale line will be transferred to a potted diseased citrus tree growing in a cage in a greenhouse and left to reproduce. Eggs will be allowed to hatch, and nymphs will be allowed to develop to the adult stage. Thirty F1, F2 and F3 adult progeny from each line will each be subjected to real time Polymerase Chain Reaction (PCR) to estimate the percentage that acquire the pathogen and relative titer of the pathogen. After screening the 45 lines for their ability to acquire the pathogen, the five most competent at acquiring the pathogen and five least competent with be selected and subjected to a detached leaf assay to assess their ability to transmit the pathogen to healthy leaves. The ability of each isofemale line to acquire Candidatus Liberibacter asiaticus (CLas) tentatively will be classified as good (greater than 70 percent F1 psyllids test positive) or poor (less than 15 percent F1 psyllids test positive). The ability of each isofemale line to transmit CLas will tentatively be classified as good (greater than 35 percent leaves become infected) or poor (less than 5 percent leaves become infected).
