Browsing by Autor "Marco Rivera"

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Pesticide misuse among small Andean farmers stems from pervasive misinformation by retailers
(Public Library of Science, 2022) Quentin Struelens; Marco Rivera; Mariana Alem Zabalaga; Raúl Ccanto; Reinaldo Quispe Tarqui; Diego Mina; Carlos Carpio; María Rosa Yumbla Mantilla; Mélany Osorio; Soraya Román
A critical issue in the context of sustainable agriculture is the reduction of pesticides. Despite well-known adverse effects, farmers around the world continue using pesticides with mostly inappropriate ways. Relevant policies have assumed that farmers themselves are primarily responsible for pesticide misuse. However, the responsibility of pesticide retailers has never been quantified due to the difficulty in obtaining reliable data. An empirical study was conducted with smallholder farmers who collected 9,670 pesticide retailers’ recommendations from 1489 surveys in the highlands of Bolivia, Ecuador and Peru. This original design allowed obtaining for the first time genuine responses about pesticide recommendations from retailers at a large scale. When comparing retailers’ recommendations with product datasheets, the results suggest that 88.2% of recommendations standards were incorrectly followed resulting in dosing recommendations that were either excessive or insufficient and accurate less than 12% of the time. An in-depth analysis also showed that 79.2% of recommended products pertained to only 6 modes of action, thus increasing the risks of pest resistance. An expert retailer model further showed that all highly toxic pesticides could be replaced by less-toxic ones. Several ways to alleviate these detrimental consequences are proposed, by acting at the root of pesticide misuse–at the retailer’s recommendation stage.
<scp>ENSO</scp> and <scp>PDO</scp> related interannual variability in the north and east‐central part of the Bolivian Altiplano in South America
(Wiley, 2021) Katherine Rojas‐Murillo; Anthony R. Lupo; Ligia García; Jere L. Gilles; Alex P. Korner; Marco Rivera
Abstract Previous studies in this region focused on interannual and interdecadal precipitation variability during Dec–Feb (summer), relating the El Niño (EN) phase to droughts. Many studies examine this variability over different parts of the Altiplano, and mountainous terrain is well‐known for producing complex climate signals as well as variability over relatively small regions. Studies that have examined climate variability over the Altiplano suggest that the El Nino Southern Oscillation (ENSO) influence is complex. The monthly precipitation, maximum and minimum temperature from 1979 to 2017 are used to examine how ENSO and PDO (Pacific decadal oscillation) influence climate conditions. Power spectra analysis determined the periodicities, and analysis of variance was applied to standardized anomalies of the three variables to evaluate PDO and ENSO as variance factors. Frequency distributions were calculated by PDO and ENSO phases, and the differences were tested using the Chi‐square test. Our results suggest a PDO and ENSO influence, displaying more dry anomalies during DJF for EN/PDO(+), in agreement with a northward position of the Bolivian high. More wet anomalies during SON (Sep–Oct–Nov) in Neutral (NEU)/PDO(+) due to an upper‐level weak westerly flow during PDO(+). For maximum temperature, a reduction in cold anomalies during EN/PDO(−) was observed along with greater warm anomalies in JJA (Jun–Jul–Aug), SON and MAM (Mar–Apr–May). Similar results were observed for NEU phase, due to a greater occurrence of high pressures centres over the region during the PDO(−). Minimum temperature results displayed more variation within stations and a less clear response to ENSO compared to PDO. The research found a clear influence of PDO in the regional climatology associated with the influence of the upper‐level jet stream using the NCEP‐NCAR composites. This provided a better understanding of these two phenomena, which would allow the production of seasonal forecasts based on ENSO and PDO using both surface and upper‐level information.