Spatial patterns of the Citrus leprosis virus and its associated mite vector in systems without intervention

Abstract

Leprosis is caused by the Citrus leprosis virus cytoplasmic type and is vectored by the mite Brevipalpus yothersi. Miticide applications, which cost $54 million annually, are based on inspection for the presence of mites. The aim of the present study was to characterize the spatial patterns of B. yothersi‐infested trees and trees with leprosis symptoms for further improvement in sampling and disease control. The presence of mites and the occurrence of leprosis were assessed over two years in 1160 Valencia trees and 720 Natal trees in a commercial sweet orange grove in Sao Paulo State, Brazil. To assess the natural growth and dispersal of mites and leprosis, mite populations were not controlled during the experimental period. Maps of mite‐infested trees and trees with leprosis symptoms were analysed at three different levels of spatial hierarchy using complementary methods, i.e. among adjacent trees within and across rows, within quadrats, and the strength and orientation of aggregation among quadrats. The study showed that the spatial patterns of virus‐infected and mite‐infested trees were different, with a strong aggregation pattern of trees with leprosis symptoms that increased over time. Conversely, the spatial pattern of B. yothersi showed randomness or weak aggregation at all three spatial hierarchical levels. Disease incidence increased steadily in plots of both cultivars, unlike in mite‐infested trees where incidence fluctuated over time. These results have important implications for the development of better management strategies for leprosis. Sampling methods and action thresholds for mite control should consider primary disease inoculum in addition to the incidence of mites.

Plant Immune System Activation Upon Citrus Leprosis Virus C Infection Is Mimicked by the Ectopic Expression of the P61 Viral Protein

“…Despite the constraint in systemic infection for CiLV-C, it causes citrus leprosis, the most important viral disease affecting the citrus industry in Brazil, the world leader in sweet orange production. Annually, prevention and control of citrus leprosis cost approximately 50 million dollars, mainly for the chemical control of the viral vector, mites of the species Brevipalpus yothersi ( Bassanezi et al., 2019 ). Endemic in the Americas, CiLV-C has spread throughout the main citrus-producing areas of the Latin American subregion ( Ramos-González et al., 2018 ).…”

Notes on the embryological development of the Brevipalpus yothersi (Acari: Tenuipalpidae)

“…Among these species, there is Brevipalpus yothersi Baker that is the main vector of citrus leprosis (CL) disease (Bassanezi et al 2019). CL severely affects the citrus industry production and has a multi-etiological viral cause (Freitas-Astúa et al 2018).…”

Molecular Epidemiology of Citrus Leprosis Virus C: A New Viral Lineage and Phylodynamic of the Main Viral Subpopulations in the Americas

“…Brazil is the leading sweet orange producer in the world. With almost 197.7 million sweet orange ( Citrus x sinensis (L.) Osbeck ) trees 1 , the citrus belt São Paulo (SP)—Minas Gerais (MG) is the largest citrus cultivation area in South America and accounts for more than 80% of the Brazilian sweet orange production ( Bassanezi et al, 2019 ). Citrus orchard yields may be impacted by citrus leprosis (CL) disease, ranked first among the viral diseases affecting this crop in Brazil ( Ramos-González et al, 2018 ).…”

“…Citrus orchard yields may be impacted by citrus leprosis (CL) disease, ranked first among the viral diseases affecting this crop in Brazil ( Ramos-González et al, 2018 ). Control of CL reaches up to US$ 54 million/year, a value representing about 5% of the management cost of orchards in the main Brazilian citrus belt ( Bassanezi et al, 2019 ).…”