1a.Objectives (from AD-416):
To evaluate citrus and citrus relatives for resistance to the Asian citrus psyllid.
1b.Approach (from AD-416):
Genotypes from the USDA Citrus Repository will be sent to the cooperator. This germplasm will be screened on site in China in choice studies to identify genotypes that are obviously susceptible as adult food and reproductive hosts. Genotypes that appear to have resistance in choice studies will be screened in no-choice studies to confirm resitance. Choice studies can be conducted in a greenhouse as well as in open field plantings. No-choice studies will be conducted by caging plants individually and introducing psyllids to determine if adults survive on the plants, if eggs are laid, and if nymphs develop on the plants to the adult stage. Germplasm with resistance will be identified. ARS will focus additional research on these genotypes to develop commercial varieties with psyllid resistsance.
This project is related to Objective 3c: Investigate basic biology and ecology of the Asian citrus psyllid and its natural enemies in Florida citrus.
Collaborators with the Fujian Academy of Agricultural Sciences (FAAS) conducted choice and no-choice experiments on resistance to Asian Citrus Psyllid (ACP) within the Rutaceae. Forty genotypes were evaluated in a free-choice experiment conducted in a screen house. Citrus tankan was completely avoided by adults, and no eggs or nymphs were ever observed on this cultivar. No eggs or nymphs were observed on various cultivars of C. reticulata; C. mitis; C. sinensis; C. grandis; and Fortunella hindsii. No-choice experiments were initiated with Poncirus accessions, and different accessions of P. trifoliata, B. koenigii and other species outside the genus Citrus were added to their field studies. FAAS’s findings are in general agreement with ARS data about susceptibility/resistance of specific germplasm studied by each group, although some germplasm that is clearly resistant to the psyllid in Florida did not appear as susceptible in China (probably due to escapes).