Dinâmica temporal da população do ácaro Brevipalpus phoenicis e da leprose dos citros sob condições naturais de epidemia

Abstract

The density of mite Brevipalpus phoenicis, vector of Citrus leprosis virus (CiLV), is determinant for decisions on control measures for citrus leprosis. Little information on the progress of incidence of trees with citrus leprosis has been compiled, either separately or together with the mite population. This study aimed to characterize the temporal growth of B. phoenicis populations and leprosis incidence on citrus trees and the relationship with these populations, under natural conditions. Two sweet orange groves, one with 'Valencia' and the other with 'Natal', were monitored from 2002 to 2004, every 22 days. The increase in disease incidence was slow and estimates of disease growth rate were quite low, varying from 0.0126 to 0.0448 for 'Valencia' and from 0.0044 to 0.0525 for 'Natal'. The initial inoculum quantity on the branches increased significantly from one cycle to the next. After the three years of observation, the incidence reached 32% in Valencia and 6.8% in Natal trees. Although not systemic, citrus leprosis has a polyetic performance, building up inoculum year after year, especially on the branches. The incidence was not correlated with the mite density on the trees in previous data collections, but presented a significant positive correlation (P<0.001) with the disease incidence reported earlier. This indicates that the presence of symptoms, rather than only the mites, must be taken into consideration in sampling aiming at disease control.