Alternative hosts of Cowpea aphid-borne mosaic virus (CABMV) in sesame (Sesamum indicum) crops grown in Paraguay

Abstract

Sesame (Sesamum indicum L.) production in Paraguay has been severely affected by infection with Cowpea aphid-borne mosaic virus (CABMV), which causes a disease known locally as ka'are. Because very little is known about the epidemiology of this disease, a survey was performed in fields surrounding affected sesame plantations to identify CABMV-infected plants that may be acting as sources of inoculum. Samples from 48 plant species (symptomatic or asymptomatic, mostly spontaneous and a few cultivated) belonging to 17 families were evaluated by biological and serological assays. In a few select cases, confirmation of the infection was achieved by RT-PCR. The following species were found to be naturally infected by CABMV: Amaranthus hybridus, Arachis hypogaea, Crotalaria incana, Crotalaria juncea, Crotalaria spectabilis, and Vigna unguiculata. The absence of resistant/tolerant sesame cultivars along with the ineffectiveness of disease control through the chemical control of aphid vectors indicates that the only alternative available for disease management at present is the elimination and/or reduction of the sources of inoculum immediately before starting new plantations.

Identification of potential hosts plants of Cowpea aphid‐borne mosaic virus

“…Among the 28 potential CABMV host species studied, viral infection was observed in Cenchrus echinatus, Leonurus sibiricus and Crotalaria spectabilis, besides Passiflora edulis (Figures 1, 2 and 4). The partial host range of CABMV is already known and most of the species systemically infected with this Potyvirus belong to the Passifloraceae (Maciel et al, 2009) and Fabaceae families (González-Segnana et al, 2013). Ocinum basilicum and Cajanus cajan tested positive for the virus, these were asymptomatic.…”

“…González‐Segnana et al. (2013) worked on the identification of potential CABMV host in sesame plantations in Paraguay and selected 48 species from of 17 different families, and most of them were invasive plants, including Amaranthus hybridus , Arachis hypogaea , Crotalaria incana , Crotalaria spectabilis and Vigna unguiculata , which tested positive for the virus in biological and serological tests.…”

“…The major concern related to the contamination of these species with CABMV is that these function as a source of viral inoculum, and owing to the ineffectiveness of disease control through the chemical control of aphid vectors (due to the non‐persistent virus/vector relationship), an available alternative for the reduction in the contamination index of yellow passion fruit plants is the elimination and/or reduction in inoculum sources before starting new plantations (González‐Segnana et al., 2013).…”

Susceptibility of common weeds and cultivated crops in major maize growing agroecological zones of Uganda to viruses causing maize lethal necrosis disease

“…Alternative hosts have been documented to have a critical role they play in the propagation of various diseases in a variety of crop species (Tugume et al, 2008;González-Segnana et al, 2013;and Macharia et al, 2016). Indeed this is the basis of various studies established to determine how other species of plants (weeds and cultivated crops) in the ecosystem of maize interact with viruses.…”