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HLB management enhancement employing the spatio-temporal epidemiology of the disease and its vector (Diaphorina citri)

Grant number: 16/01796-1
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): May 01, 2016
Effective date (End): February 27, 2019
Field of knowledge:Agronomical Sciences - Agronomy
Principal Investigator:José Belasque Junior
Grantee:Kelly Pazolini
Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
Associated scholarship(s):17/03122-0 - HLB management enhancement using spatio-temporal analyses of the disease and its vector (Diaphorina citri), BE.EP.DR

Abstract

The citrus industry is an important agro-industrial activity in Brazil and much of the production is concentrated in São Paulo, which accounts for 73% of citrus production in the country. A major challenge for São Paulo citrus industry is the current epidemic of Huanglongbing (HLB), a disease considered the main threat to world citrus production. The HLB is associated with the bacterium 'Candidatus Liberibacter spp.' and its dissemination that occurs by vector Diaphorina citri. The management of HLB is based on chemical vector control, eradication of infected plants and planting of healthy seedlings. However, when these control measures are applied only locally, for example on a property surrounded by areas of diseased plants, it can not reduce the effects of primary dissemination. This primary dissemination occurs by the migration of D. citri infective adults, from surrounding areas maintained with inoculum sources. Thus, new infections occur even in areas under strict management of the disease (in this case meant eradication of plants and the use of insecticides). In this scenario, epidemiological studies are needed to determine the effectiveness of these control measures, to estimate their cost/benefit analysis and propose management alternatives. In this research proposal will be determined the spatial and temporal progress of HLB in orchards of citrus property that takes control strategies described above but suffers in different magnitudes, the influence of neighboring areas, with and without the management of HLB. Therefore, it will be adjusted the monomolecular, logistic and Gompertz temporal models to data of eradication of stands of plants: i) located on the edge and more internally on the property; and ii) with different planting densities (5.0 to 6.5 m 1.5 x 2.5 m). To spatial progress of HLB, will be adjusted disease gradient models and determined the edge effect. Furthermore, the correlation between the fluctuation of the vector population and its magnitude in the rate of progress of the disease and the edge effect is observed. Finally, the Markov-Chain Monte Carlo (MCMC) simulation method will be applied to spacial-temporal progress of HLB to estimate the effects of primary and secondary disseminations. The results obtained will serve as a model for the establishment of new strategies for the presence of citrus HLB.