Delphacodes kuscheli Fennah (Hemiptera: Delphacidae) is the main natural vector of Mal de Rio Cuarto virus (family Reoviridae, genus Fijivirus, MRCV), which infects different gramineae and causes the most important maize (Zea mays L.) disease in Argentina. MRCV—vector interactions usually are studied using different winter cereals as hosts. Under experimental conditions, <50% of D. kuscheli planthoppers fed on a MRCV-infected plant can transmit the virus to wheat (Triticum aestivum L. ). This fact is influenced by insect development stage at acquisition and the latency period. This work describes the relation between transmission efficiency and MRCV accumulation in its planthopper vector. First- and third-instar D. kuscheli nymphs were allowed to feed on MRCV-infected plants, and 9 or 17 d after the acquisition access period (AAP), viral load of transmitting and nontransmitting planthoppers was quantified by quantitative polymerase chain reaction. The transmitting planthoppers showed significantly higher viral titers than nontransmitting ones, suggesting that successful transmission is positively associated to viral accumulation in the insect. However, planthoppers of the third-instars group did not transmit the virus 9 d after AAP, even when 46% had similar titers to the transmitting insects of the other treatments. These results indicate that additional factors influence MRCV transmission efficiency when acquisition occurs in older planthoppers. This is the first precise quantitative analysis of MRCV in its main vector species and will definitely contribute to better understand planthopper—Fijivirus interactions and its epidemiological implications.

Peri-urban vegetable cropping areas, such as horticultural farms, provide several ecosystem services, such as the provision of fresh food. However, food supply must be estimated on the basis of the current and potential demand of future populations, taking into account the landscape carrying capacity towards sustainable agricultural planning. From this perspective, the study aimed at estimating the resilience of the “Agri-food Region of Central Córdoba” (ARCC) and its role in supporting the provisioning of ecosystem services, such as proximal services, provided by the diversified agricultural landscape in the peri-urban area of Córdoba (Argentina). A direct field survey has been carried out to collect data on the main species and types of crops, the annual productivity, and the area covered by each species and type of horticultural crops. The data have been statistically elaborated to test the spatial and temporal variability of productivity as well as the spatial autocorrelation. In relation to crop diversification, a total of 30 vegetable species have been recorded in the diversified farms under study, with 15 species identified as the most frequent crops as on the basis of the area dedicated to each vegetable species sampled in the farms (in %). The productivity of 30 species has been integrated into a single value of “vegetable crop productivity mean” (kg/m²), proposed and measured in this study, which has been 3.46 kg/m². It can be a useful monitoring indicator in diversified production contexts. The estimated food supply (ton/year) of vegetable crops for the 170 farmlands has been 72,881 ton/year. An accurate measurement of the biomass harvested on a given surface area can be useful to assign productivity data to the pixel of each land use/cover class, providing accurate input data for remotely sensed-based models supporting decision-making on food provision in peri-urban systems. In this sense, the paper proposes a methodological framework that can be useful worldwide when up-to-date official productivity data are not available, but they are a necessary basis for planning, decision-making, and the implementation of public policies. Thus, diversity in farming systems can combine high ecological and socio-economic benefits, in terms of ecosystem service provision and sustainable food production.

Planthoppers are important worldwide crop pests as well as vectors of numerous diseases. Different species transmitMal de Río Cuarto virus, which causes the most economically important corn disease in central Argentina. Epidemiological studies rely on the accurate identification of the species present in the field. Presently, morphological identification of planthoppers requires taxonomic expertise and there are no taxonomic keys for females and nymphs. Nevertheless, no molecular protocols are available for accurate species identification of most frequent delphacid species from central Argentina. In this context, the aim of this study was to evaluate the utility of the cytochrome oxidase I gene (COI) as a DNA barcode and its digestion with restriction enzymes (Restriction Fragment Length Polymorphism, RFLP) for the identification of the most common species of planthoppers in central Argentina. We amplified and sequenced a 843 bp fragment of the COI gene of taxonomically identified specimens and evaluated its use as a DNA barcode. Restriction enzymes were also selected for digesting the COI fragment via RFLP. The high interspecific variability (20.79%; ± 2.32%) and low intraspecific divergence (0.12%; ± 0.17%) observed in the studied species, demonstrate the effectiveness of the COI gene for species identification of major vector delphacids affecting corn crops in Argentina. Moreover, the digestion of this COI gene fragment withBfaI andApoI enzymes allows a fast and cost-effective species identification method when numerous specimens need to be processed. Both molecular techniques developed here, allow the accurate identification of planthopper species at regional scale. These new tools would assist traditional identification of these insects, especially for aiding non-experts in morphological taxonomy.

La transformación de los sistemas hortícolas periurbanos convencionales hacia un modelo agroecológico con mayor sustentabilidad socioambiental requiere de una articulación sinérgica de saberes, experiencias y recursos de los actores institucionales de investigación, extensión rural y los productores. Con el objeto de contribuir a mejorar la sustentabilidad productiva, ambiental y social del Cinturón Verde de la Ciudad de Córdoba (cvc) (Córdoba, Argentina), se inició un proceso que involucra actividades de investigación participativa, desarrollo tecnológico y extensión rural, para promover la transición hacia prácticas agroecológicas en productores hortícolas familiares de áreas periurbanas. Bajo un enfoque sistémico, el «Equipo interinstitucional de apoyo a la intensificación ecológica de la producción de alimentos de proximidad» focaliza sus acciones en «aprender haciendo» a través de la metodología Investigación Acción Participativa (iap), construyendo redes, confiriendo importancia al conocimiento tácito, científico, experimental y situado, coconstruido entre todos los actores. En el presente trabajo se realiza un breve análisis del contexto tecnológico-productivo de los sistemas hortícolas periurbanos del cvc y la concreta articulación entre la extensión y la investigación con una mirada sistémica para generar posibles soluciones a estas complejas problemáticas. La incorporación de bioinsumos en los sistemas productivos de los productores participantes forma parte de nuestros resultados; sin embargo, el mayor logro es la integración y la vinculación de los actores involucrados en la coconstrucción de conocimiento y el impacto que estos procesos implican para posibles reconfiguraciones de intervención institucional y vinculación tecnológica.

Broad bean ( Vicia faba L) is the fourth most important pulse crop in the world. In Argentina, broad bean production was of 1,841 hectares and 16,500 tons during the 2017 growing season. Broad bean is commonly used in rotations; especially by farmers located in “green belts” that are peri-urban areas surrounding large cities that include horticultural family farms. Plants showing marked foliar mosaic symptoms, typical of viral infection, were collected during the 2015 growing season in the green belt of Córdoba city, Argentina. Preparations of symptomatic tissues were mechanically inoculated onto healthy broad bean plants in the greenhouse, which developed symptoms similar to those observed in the field. In addition, symptomatic samples were positive when tested by indirect ELISA with the anti - potyvirus group monoclonal antibody. Further, flexuous filamentous particles typical of potyviruses were observed under the electronic microscope on dip preparations. Lastly, total RNA was extracted from a symptomatic leaf and high-throughput sequenced, which allowed the assembly of a single virus sequence corresponding to a new highly divergent strain of Bean yellow mosaic virus (BYMV). Phylogenetic insights clustered this Argentinean broad bean isolate (BYMV-ARGbb) within group IX of BYMV. Given the economical importance of this virus and its associated disease, the results presented here are a pivotal first step oriented to explore the eventual incidence and epidemiological parameters of BYMV in broad bean in Argentina.