Temporal and spatial progress of Cowpea aphid-borne mosaic virus (CABMV) in passion fruit (Passiflora edulis Sims)

Abstract

Among the diseases that affect passion fruit, those causing fruit woodiness is considered the most important. Cowpea aphid-borne mosaic virus (CABMV) is an important vírus that is transmitted by several aphid species during the bite, making the use of insecticides infeasible to control these vectors. In order to understand the epidemiological behavior of the disease, this study aimed to study the temporal progress and spatial pattern of CABMV in the field. Healthy seedlings of passion fruit with 2.0 meters height were implanted in the field condition at the experimental station of the IDR-Paraná, Brazil. The evaluations were performed weekly observing the symptoms of blister, mosaic, chlorosis and crinkled leaves. For the analyses, the logistic, gompertz and monomolecular models were adjusted to CABMV incidence data in passion fruit. The spatial pattern of the disease was characterized by the dispersion index and Taylor's Power Law. The logistic model was the one that best described the progress in the incidence of the disease. The incidence progress rate of CABMV was 0.037, 0.077 and 0.060 % day-1. At the beginning of the epidemic, the pattern was random. The initial dispersion mechanism was occured through aphid vectors, como Aphis gossypii Glover, Aphis fabae Scopoli, Aphis solanella Theobald, Toxoptera citricida Kilkaldy, Uroleucon ambrosiae Thomas and Uroleucon sonchi L. infected with CABMV that starts its test bite randomly. The pattern of disease dispersion began to be added when the incidence of plants reached 10 and 7%, in the 2015/16 and 2017/18 harvests, respectively. The random spatial pattern suggested that infected aphids enter several points of the orchard and infected plants become a source for secondary infections, characterizing aggregate pattern. Thus, the eradication of alternative hosts abroad can be adopted as management strategies of CABMV