Aerobiology of the Wheat Blast Pathogen - Inoculum Monitoring and Detection of Fungicide Resistance Alleles

Wheat blast, caused by the ascomycetous fungus Pyricularia oryzae Triticum lineage (PoTl), is mainly controlled by fungicide use, but resistance to the main fungicide groups—sterol demethylase (DMI), quinone outside (QoI), and succinate dehydrogenase inhibitors (SDHI)—has been reported in Brazil. In order to rationalize fungicide inputs (e.g., choice, timing, dose-rate, spray number, and mixing/alternation) for managing wheat blast, we describe a new monitoring tool, enabling the quantitative measurement of pathogen’s inoculum levels and detection of fungicide resistance alleles. Wheat blast airborne spores (aerosol populations) were monitored at Londrina in Paraná State, a major wheat cropping region in Brazil, using an automated high-volume cyclone coupled with a lab-based quantitative real-time PCR (qPCR) assay. The objectives of our study were as follows: (1) to monitor the amount of PoTl airborne conidia during 2019–2021 based on DNA detection, (2) to reveal the prevalence of QoI resistant (QoI-R) cytochrome b alleles in aerosol populations of wheat blast, and (3) to determine the impact of weather on the dynamics of wheat blast aerosol populations and spread of QoI resistant alleles. PoTl inoculum was consistently detected in aerosols during the wheat cropping seasons from 2019 to 2021, but amounts varied significantly between seasons, with highest amounts detected in 2019. High peaks of PoTl DNA were also continuously detected during the off-season in 2020 and 2021. The prevalence of QoI resistant (QoI-R) cytochrome b G143A alleles in aerosol populations was also determined for a subset of 10 PoTl positive DNA samples with frequencies varying between 10 and 91% using a combination of PCR-amplification and SNP detection pyrosequencing. Statistically significant but low correlations were found between the levels of pathogen and the weather variables. In conclusion, for wheat blast, this system provided prior detection of airborne spore levels of the pathogen and of the prevalence of fungicide resistance alleles

Potential impact of future climates on rice production in Ecuador determined using Kobayashi´s 'Very Simple Model'.

Abstract: Rice (Oryza sativa L.) is the main staple food of more than 50% of the world´s population. However, global production may need to increase by more than 70% before 2050 to meet global food requirements despite increasing challenges due to environmental degradation, a changing climate, and extreme weather events. Rice production in Ecuador, mainly concentrated in lowland tropical plains, declined in recent years. In this paper, we aim to calibrate and validate KobayashÍ´s 'Very Simple Model' (VSM) and, using downscaled corrected climate data, to quantify the potential impact of climate change on rice yields for Ecuador´s two main rice-growing provinces. The negative impact is expected to be highest (up to -67%; 2946 tons) under the Representative Concentration Pathway (RCP) 8.5, with a lower impact under RCP 2.6 (-36%; 1650 tons) yield reduction in the Guayas province. A positive impact on yield is predicted for Los Ríos Province (up to 9%; 161 tons) under RCP 8.5. These different impacts indicate the utility of fine-scale analyses using simple models to make predictions that are relevant to regional production scenarios. Our prediction of possible changes in rice productivity can help policymakers define a variety of requirements to meet the demands of a changing climate

Taxonomic and Ecogeographic Predictors of Resistance Against Phthorimaea operculella Zeller in Wild Potato Tubers

Taxonomic and ecogeographic information are potentially useful to select plants with beneficial traits for crop breeding. We tested the predictability of taxonomic and geoclimatic information in identifying wild potatoes with resistance in tubers to the potato tuber moth, Phthorimaea operculella Zeller. We tested the tubers of 47 wild potato species and the native potato Solanum tuberosum andigena for resistance to tuber moth larvae. Materials included 6585 genotypes representing 558 accessions. During screening, 28% of accessions had ≥ 60% undamaged tubers (moderate resistance) and of these, 10% were highly resistant to moth damage (i.e., ≥ 80% of tubers undamaged). Tubers of six potato species (S. commersonii, S. chiquidenum, S. albicans, S. acaule, S. demissum and S. boliviense) were significantly more resistant than tubers of S. tuberosum andigena, but resistant accessions also occurred among 22 other Solanum species. The frequency of resistant accessions was similar across phylogenetic clades, but resistance was more frequent in accessions with an endosperm balance number (EBN) of 1 or 4 and a ploidy level of 4 × or 6 × . There was no apparent relation between altitude of origin and tuber resistance. Ecogeographical information was weakly related to resistance in some potato species; minimum temperatures during the coldest months at collection sites were positively related to resistance in S. boliviense and S. medians. Mean high temperatures and summertime precipitation were positively related to resistance in S. microdontum and S. acaule, respectively; however, ecogeographic information was not generally useful in predicting tuber resistance for other species or across all species. We recommend improvements to the phenotyping of potato accessions for resistance to tuber moth, including the use of taxonomic predictors

First records of parasitoids attacking the Asian citrus psyllid in Ecuador.

Made available in DSpace on 2017-11-20T23:21:50Z (GMT). No. of bitstreams: 1 NTC17003.pdf: 1248364 bytes, checksum: 7b2274d1c3f65bd302b0ee0864de97c0 (MD5) Previous issue date: 2017-08-07bitstream/item/167044/1/NTC17003.pd

Manipulation of Agricultural Habitats to Improve Conservation Biological Control in South America

International audienceStable and diversified agroecosystems provide farmers with important ecosystem services, which are unfortunately being lost at an alarming rate under the current conventional agriculture framework. Nevertheless, this concern can be tackled by using ecological intensification as an alternative strategy to recuperate ecosystem services (e.g., biological control of pests). To this end, the manipulation of agricultural habitats to enhance natural enemy conservation has been widely explored and reported in Western Europe and North America, whereas in other parts of the world, the investigation of such topic is lagging behind (e.g., South America). In this forum, we gathered published and unpublished information on the different ecological habitat management strategies that have been implemented in South America and their effects on pest control. Additionally, we identify the various challenges and analyze the outlook for the science of conservation biological control in South America. More specifically, we reviewed how different agricultural practices and habitat manipulation in South America have influenced pest management through natural enemy conservation. The main habitat manipulations reported include plant diversification (intercropping, insectary plants, agroforestry), conservation and management of non-crop vegetation, and application of artificial foods. Overall, we noticed that there is a significant discrepancy in the amount of research on conservation biological control among South American countries, and we found that, although intercropping, polycultures, and crop rotation have been reported in agroecosystems since pre-Inca times, more systematic studies are required to evaluate the true effects of habitat management to implement conservation biological control for pest control in South America