ABSTRACT The Barley yellow dwarf virus or Barley Yellow Dwarf Virus (BYDV) is one of the aphid-borne diseases present in many wheat-producing regions of the world, causing significant losses. Identifying the species that transmit the disease is very important, in order to management tactics and to avoid its spread. The object of this study is to identify BYDV-transmitting aphid species in wheat crops in the areas of highest production in Paraguay; Alto Paraná, Itapúa, Caaguazú and San Pedro. The research was carried out from the start of the seedling emergence to the final stage of wheat cultivation, which ranged from May to October 2014. The insects were captured weekly in each of the selected plots in Moericke-type traps. The data were subjected to fauna analysis. Five species of aphids were identified: Rhopalosiphum padi, Rhopalosiphum maidis, Sitobion avenae, Schizaphis graminum, Rhopalosiphum rufiabdominalis, all identified species are considered virus transmitters.

RESUMEN El Barley yellow dwarf virus o Virus del Enanismo Amarillo de la Cebada (BYDV) es una de las enfermedades transmitidas por áfidos presente en muchas regiones productoras de trigo del mundo, causando mermas importantes en la producción. Identificar las especies que transmiten la enfermedad es de suma importancia, a fin de encarar tácticas de manejo, para evitar la diseminación de la misma. El estudio tiene como objetivo identificar especies de áfidos transmisores del BYDV en cultivos de trigo de las zonas de mayor producción del Paraguay. Los trabajos de trampeo de especímenes se realizaron desde el inicio de la emergencia de las plántulas hasta la etapa final del cultivo de trigo que comprendió entre los meses de mayo hasta octubre del año 2014. Los insectos fueron capturados semanalmente en cada una de las parcelas seleccionadas en trampas tipo Moericke. Los datos fueron sometidos a análisis faunísticos. Se identificaron cinco especies de áfidos, Rhopalosiphum padi, Rhopalosiphum maidis, Sitobion avenae, Schizaphis graminum, Rhopalosiphum rufiabdominalis, todas las especies identificadas son consideradas transmisoras de virus.

ABSTRACT In agroecosystems, there are natural enemies controlling cereal aphids, regulating their population. The study of identification and quantification is important for the integrated pest management of wheat. The research aims to identify families of predators and aphid parasitoids present in wheat crops in the departments of; Alto Paraná, Itapúa, Caaguazú and San Pedro. The insects were collected weekly from Moericke traps installed in wheat crops, from the beginning of emergence of the seedlings to the final stage, between May and October 2014. Nine species of parasitoids were identified, Lysiphlebustestaceipes, Ephedrusplagiator, Praongallicum, Praonvolucre, Aphidiuscolemani, Aphidiuspicipes, Aphidiuservi, Aphidiusuzbekistanicus, Aphidiusrhopalosiphi and four families of predators of Hemerobiidae, Coccinellidae. Coenagrionidae, Chrysopidae.

RESUMEN En los agroecosistemas, existen enemigos naturales controladores de áfidos de cereales, regulando la población de los mismos. El estudio de la identificación y cuantificación es importante para el manejo integrado de plagas del trigo. La investigación tiene como objetivo identificar familias de predadores y especies de parasitoides de áfidos presentes en cultivos de trigo en los departamentos de; Alto Paraná, Itapúa, Caaguazú y San Pedro. Los insectos fueron colectados semanalmente en trampas tipo Moericke instaladas en cultivos de trigo, desde el inicio de la emergencia de las plántulas hasta la etapa final, entre los meses de mayo a octubre del año 2014. Fueron identificados nueve especies de parasitoides, Lysiphlebus testaceipes, Ephedrus plagiator, Praon gallicum, Praon volucre, Aphidius colemani, Aphidius picipes, Aphidius ervi, Aphidius uzbekistanicus, Aphidius rhopalosiphi y cuatro familias de predadores de Hemerobiidae, Coccinellidae. Coenagrionidae, Chrysopidae.

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.