Transgenic Bt maize that produces less than a high-dose has been widely adopted and presents considerable insect resistance management (IRM) challenges. Western corn rootworm, Diabrotica virgifera virgifera LeConte, has rapidly evolved resistance to Bt maize in the field, leading to local loss of efficacy for some corn rootworm Bt maize events. Documenting and responding to this resistance has been complicated by a lack of rapid diagnostic bioassays and by regulatory triggers that hinder timely and effective management responses. These failures are of great concern to the scientific and agricultural community. Specific challenges posed by western corn rootworm resistance to Bt maize, and more general concerns around Bt crops that produce less than a high-dose of Bt toxin, have caused uncertainty around current IRM protocols. More than 15 years of experience with IRM has shown that high-dose and refuge-based IRM is not applicable to Bt crops that produce less than a high-dose. Adaptive IRM approaches and pro-active, integrated IRM-pest management strategies are needed and should be in place before release of new technologies that produce less than a high-dose. We suggest changes in IRM strategies to preserve the utility of corn rootworm Bt maize by 1) targeting local resistance management earlier in the sequence of responses to resistance and 2) developing area-wide criteria to address widespread economic losses. We also favor consideration of policies and programs to counteract economic forces that are contributing to rapid resistance evolution.

/pdf/early-detection-and-mitigation-of-resistance-to-bt-maize-by-12f16ttond.pdf

Early Detection and Mitigation of Resistance to Bt Maize by Western Corn Rootworm (Coleoptera: Chrysomelidae)

Plants are the first step of a metal’s pathway from the soil to heterotrophic organisms such as animals and humans, so the content of metallic trace elements in edible parts of a plant represent available load of these metals that may enter the food chain through plants. Among metal elements, Cu, Fe, Mn, and Zn are micronutrients as they are essential in trace amounts for physiological processes in living organisms and therefore are a significant component of the soil–plant–food continuum. Billions of people around the world suffer from micronutrient malnutrition. This review is aimed at giving an overview of the data pertaining to the Fe, Mn, Zn, and Cu content of the grains of the globally most important cereals – wheat, rice, and maize, reported mostly during the last two decades. The prevailing opinions on their importance in the food chain, and current strategies for enrichment of cereal grains with those essential microelements are briefly summarized.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/fes3.24

Metallic trace elements in cereal grain – a review: how much metal do we eat?

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is one of the most important pest species of maize in several countries of Central and Eastern Europe. This pest insect has invaded from the USA and is mainly controlled by insecticides in the EU. In the USA reliance on insecticides seems to decrease due to transgenic maize production. The EU project Diabr-Act aims at establishing a harmonized and sustainable control strategy for western corn rootworm populations in Europe. In this respect, current chemical control strategies used in the USA and EU are described. Seed, soil and foliar treatments as well as transgenically protected maize are discussed. Specific attention is given to insecticide resistance. Seed treatment has clear environmental benefits, but factors influencing the efficacy should be declared. Soil and foliar treatments have perspectives, though new technologies limiting environmental hazards should be considered. Transgenic maize may have serious perspectives

Chemical control of Diabrotica virgifera virgifera LeConte

Growing crop plants tolerant to acid soils is an alternative for successful production on acid soils with limited inputs, especially lime. Acid soil‐ or aluminum (Al)‐tolerant plants offer considerable protection against soil acidity problems. Thirteen maize (Zea mays L.) hybrids developed for production under various environmental conditions were grown (greenhouse) on two acid soils (unlimed and limed) to determine differences among hybrids for growth traits, mineral acquisition, and relative tolerance to acid soil. Porters soil induced greater acid soil stress on maize than did Lily soil, although shoot/root dry matter (DM) ratios were affected more in plants grown on Lily than on Porters soil. Shoot and root DM and total root length (RL) over all hybrids followed sequences of Limed Lily ≥ Limed Porters > Unlimed Lily > Unlimed Porters, and the trait with the greatest variation among hybrids was total RL. Specific RL (total RL/root DM) over all hybrids followed a sequence of Limed Lily=Limed Po...

Growth traits and mineral concentrations of maize hybrids grown on unlimed and limed acid soil

Durum wheat has the tendency of accumulating more cadmium (Cd), a biotoxic heavy metal, in seeds than other commonly grown cereals, thus posing a serious food safety/public health concern. This could have serious negative impact on the national pasta industry and the international export market of durum wheat. The phenotyping for selecting low Cd lines is expensive and time consuming. The use of markers could be a more sustainable approach for selecting lines with low Cd levels. Here, a RIL population developed from a cross between Grenora (high Cd) × Haurani (low Cd) and two association mapping panels consisting of advanced breeding lines from the North Dakota durum wheat breeding program were used to identify QTL and associated markers for Cd. A major QTL, with Haurani contributing low Cd uptake allele and explaining 54.3 % phenotypic variation, was detected on chromosome 5BL. Association mapping using 2010 collection validated the results of linkage mapping and identified major QTL on 5BL. The 2009 collection, showed the presence of a major QTL on chromosome 2B. The SNP marker associated with major QTL on 5BL was converted to user friendly KASPar assay. The major QTL and associated KASPar marker were further validated using another RIL population developed from a cross of Strongfield (low Cd) and Alkabo (high Cd). The development of suitable marker assay, associated with major Cd uptake QTL, would help the selection for low Cd accumulating lines, minimizing the costly phenotypic evaluation for this important trait.

Identification and validation of a major cadmium accumulation locus and closely associated SNP markers in North Dakota durum wheat cultivars

This review presents the latest research regarding maize resistance breeding against western corn rootworm (WCR) in the U.S.A. and Europe. Investigations in Europe on the development of maize cultivars possessing resistant mechanisms against WCR are just beginning. In 2003, the European Commission implemented measures aimed at slowing down the spread of the WCR in Europe. Nevertheless, this pest has already been found in 20 countries of the European region. To establish a sustainable production system, the evaluation of native (nontransgenic) resistance in maize cultivars is essential.This review emphasizes the future challenges involved in the research of native resistance breeding in maize against the insect.

A review of resistance breeding options targeting western corn rootworm (Diabrotica virgifera virgifera LeConte).

The western corn rootworm ( Diabrotica virgifera virgifera LeConte (WCR)) is a major pest of corn in USA. The pest arrived in Croatia in 1995, and today over 250.000 ha are infested. Insecticides are regularly used to control WCR, but the cost is high, can pose environmental risks, and may become ineffective due to resistance. Growing corn that is resistant to corn rootworms would be a valuable alternative to insecticides. Nine Croatian (Institute of Agriculture, Osijek) and two Pioneer Hi-Bred Int. Inc. (Johnston, Iowa, USA) commercial corn hybrids were evaluated for WCR resistance at two locations using complete randomized block design with four replications. One location was in east Croatia (Osijek) and one was in the USA (Iowa). The hybrids’ tolerance to larval feeding was rated using root injury, root regrowth and root size. Root injury was rated using the Node-Injury Scale 0–3 and evaluation of root size and root regrowth were done by scale 1–6. In an analysis of variance combined across locations, ...

/pdf/evaluation-of-corn-hybrids-for-tolerance-to-corn-rootworm-pkj2p73hpi.pdf

Evaluation of corn hybrids for tolerance to corn rootworm (Diabrotica virgifera virgifera LeConte) larval feeding

Kukuruzna zlatica je znacajan stetnik u Americi, a u Europi je otkrivena 1992. Od tad je prosirena u dvadeset zemalja Europe. U Hrvatskoj je prvi put otkrivena 1995.Najveca brojnost ovog stetnika javlja se pri uzgoju kukuruza u monokulturi. Imago je kornjas koji se javlja u lipnju i hrani se na liscu, polenu i svili kukuruza. Od polovine srpnja do konca rujna odlaže jaja u tlo i ona prezime u tlu. Licinke se javljaju koncem svibnja ili pocetkom lipnja do konca srpnja, hraneci se na korijenu kukuruza. Najvece stete cine licinke koje izgrizaju korjen kukuruza. Simptomi napada su vidljivi u oblik tzv. guscjeg vrata uslijed izgriženog korijena. Pregled povrsina obavlja se u proljece i jesen, sondama promjera 10 cm, radi utvrđivanja brojnosti jaja. Prisustvo imaga utvrđuje se u srpnju, kolovozu i rujnu i to mamcima ili pregledom svile. Ako se u jednom danu uhvati preko 5 zlatica po mamcu (žute ploce) ta se povrsina iduce godime mora tretirati insekticidima. Za suzbijanje najvažniji je plodored (3-4 godine) tolerantni hibridi, agrotehnicke mjere, prirodni neprijatelji te insekticidi primjenjeni kod sjetve. Suzbijanje imaga opravdano je kod sjemenske proizvodnje, ali se mora voditi racuna o pragu odluke ili o broju gravidnih ženki. Hibridi (OS 430, OS 499, OSSK 515, OSSK 602, OSSK 617) Poljoprivrednog instita Osijek pokazali su tolerantnost na kukuruznu zlaticu

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera, Chrysomelidae)

Twenty corn (Zea mays L.) hybrids were grown under field conditions in the west part of Brodsko-posavska county in Eastern Croatia during 2000 and 2001 growing seasons. The field trial was conducted in four replicates. The ear-leaf at beginning of silking stage (the second decade of July) was taken for chemical analysis from each plot. Mean soil sample was taken by auger to 30 cm of depth. The total amounts of Cd and Pb in corn leaves were measured by ICP-AES technique after their microwave digestion using concentrated HNO3+H2O2. Mobile fraction of these elements in soil was extracted by ammonium acetate-EDTA solution. The experimental field is acid hydromorphic soil (locality Malino) with moderate levels of mobile fractions of calcium, magnesium and aluminum. Also, mobile fraction of cadmium and lead are tolerable for growing of health food. Weather conditions during the study differed from the long-term mean. Low rainfall quantities during 5-months period and the higher air-temperatures characterized the 2000 growing season. Excess of rainfall in June and September, their shortage in July and August, as well as high temperatures in August, are main characteristics of weather during the corn growing seasons in 2001. Mean concentrations of cadmium and lead in corn leaves in our investigations were 0.14 ppm Cd and 0.420 ppm Pb. These amounts are low and not dangerous for plants, because critical concentrations of Cd and Pb in plants ranged from 5 to 10 ppm Cd and 10-20 ppm Pb. Considerable differences of cadmium and lead status in the ear-leaf were found among tested corn hybrids. For example, genetically induced differences from 0.07 to 0.21 ppm Cd were found, while these values for Pb were from 0.241 to 0.569 ppm Pb. Especially low Cd concentrations were found in six corn hybrids (OsSK373, E9917/99, Bc278, OsSK2-191, OsSK382 and Clarica: mean 0.092 ppm Cd), while in three hybrids it was considerably higher, but acceptable from the aspect of plant and animal health (OsSK395, OsSK378 and Tvrtko 303: mean 0.200 ppm Cd). Very low Pb concentrations were found in two hybrids (Clarica and OsSK373: mean 0.268 ppm Pb), while in three hybrids they were above 0.500 ppm Pb (RK1456/99, osSK382 and Bc278: mean 0.542 ppm Pb). In general, production of healthy food based on principles of sustainable agriculture is possible under tested environmental conditions

Cadmium and lead status in corn hybrids grown on acid soil of Eastern Croatia

Limited results are published about the relations among micronutrients in cereal grains, although micronutrients play important physiological roles in animals and humans. The objective of this study was to determine relations among boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) concentrations in grain of 297 genotypes of a maize population measured by inductively coupled plasma – optical emission spectrometry (ICP-OES) in two years. Correlation coefficients showed generally weak, though positive associations between individual micronutrient concentrations in both years. Principal component analysis revealed not the same relations among the micronutrients across two years, indicating the importance of environment. Still, close relations between Cu and Fe, and to lesser extent between B and Mo were observed in both years. Mn was consistently one of the least related micronutrients to others. Our results suggest that it is possible to improve density of various micronutrients in maize grain simultaneously, although the progress would be very slow.

/pdf/relations-among-six-micronutrients-in-grain-determined-in-a-2i56yh47mt.pdf

Relations among six micronutrients in grain determined in a maize population

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