Development of a pathogen dispenser to control Asian citrus psyllid  (ACP) in residential and organic citrus.

Development of a pathogen dispenser to control Asian citrus psyllid (ACP) in residential and organic citrus.

Report Date: 02/18/2011
Project: 58-6204-1-092 CRB 5500-187
Category: ACP Vector
Author: Joseph M. Patt
Sponsor: California Citrus Research Board

Report: ACP dwelling in rutaceous plants outside of commercial citrus orchards are a source of HLB. If not controlled, these ACP will stymie the effectiveness of area-wide management programs aimed at containing the spread of HLB in commercial citrus. The proposed research is to develop an autodisseminator (‘dispenser’) of pathogen spores for controlling ACP in residential and organic citrus. The working hypothesis is that ACP will visit the dispenser, pick-up spores, and infect other psyllids when they return to the foliage. The dispenser will be coated with spores of the fungus Isaria fumosorosea (Ifr), a known pathogen of ACP, and will be designed to attract and retain psyllids and to efficiently infect them with spores. Greenhouse tests will determine if infected psyllids can transmit the pathogen to immatures and adult cohorts. Tests will be conducted in local communities to determine if the dispenser can effectively infect ACP in residential trees and to assess spore viability over time. Information from these tests will be used to optimize ACP attraction to the dispenser and spore viability and transfer. The ultimate goal is to design a dispenser that is effective and safe, acceptable to regulatory agencies, and readily adopted by homeowners and organic growers. Exposure of free-fly ACP in a greenhouse resulted in an average of 55% of the ACP becoming infected with pathogen spores (n = 3 trials), demonstrating that the proposed concept is very plausible. The dispenser used for greenhouse tests is constructed from a 21.25 cm x 27.5 cm (8.5 in. x 11 in.) sheet of bright yellow stock paper rolled into a tube with eight pleated ridges running lengthwise across its surface. ACP prefers to crawl along edges and the ridges increase ACP retention on the device, in turn increasing the likelihood of spore infection. The inner portion of each pleat is coated with a thin line of SPLAT (ISCA Technologies, Inc.), an emulsified wax used to dispense scent compounds. The SPLAT contains a standardize aliquot (10’l scent mixture per 10 ml SPLAT) of a terpene mixture based on the emission of volatiles from growing terminal shoots of ACP host plants. Ongoing tests are showing that scented SPLAT induces significantly more probing by ACP than unscented SPLAT. Greenhouse tests will be soon be initiated to determine whether nymphs can be infected from adults carrying Ifr blastospores.


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