Neither transgenic Bt maize (MON863) nor tefluthrin insecticide adversely affect soil microbial activity or biomass: A 3-year field analysis

Devare, Medha; Londoño-R, Luz Marina; Thies, Janice E.

doi:10.1016/j.soilbio.2007.03.004

Cited by 67 publications

(42 citation statements)

References 49 publications

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“…This is consistent with the results of several other studies that have reported no changes in the abundance or composition of bacterial and fungal communities in field soils where Bt corn was planted or in soils amended with Bt corn biomass and incubated under glasshouse conditions (Saxena and Stotzky, 2001a;Blackwood and Buyer, 2004;Devare et al, 2004Devare et al, , 2007Icoz et al, 2008). Similarly, the numbers of culturable bacteria and fungi, and the activity of enzymes involved in degrading Bt plant biomass did not differ significantly from those associated with non-Bt plant biomass, confirming laboratory observations that the Cry1Ab protein is not toxic to a spectrum of pure and mixed cultures of microbes (Koskella and Stotzky, 1997).…”

Section: Bacterial and Fungal Communities Colonizing The Surface Of Csupporting

confidence: 92%

“…The Bt protein may also be released by decomposing plant residues incorporated into soil after crop harvesting. Thus far, no adverse effects have been reported on the abundance or diversity of bacterial or fungal communities in the rhizosphere of Bt corn (Blackwood and Buyer, 2004;Devare et al, 2004Devare et al, , 2007 or in soils into which ground residues have been added (Saxena and Stotzky, 2001a). Decreased rates of respiration from soils in which residues from six Bt crops had been incorporated were observed in one laboratory incubation (Flores et al, 2005), although no mechanism to explain these observations was proposed.…”

Section: Introductionmentioning

confidence: 97%

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In-field rates of decomposition and microbial communities colonizing residues vary by depth of residue placement and plant part, but not by crop genotype for residues from two Cry1Ab Bt corn hybrids and their non-transgenic isolines

Londoño-R

Tarkalson²,

Thies

2013

Soil Biology and Biochemistry

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a b s t r a c tThe adoption of Bt corn has been largely overshadowed by concerns about their unintended effects on human health and the environment. Residues of transgenic Bt crops decomposed more slowly than their non-transgenic isolines in one laboratory study, although no mechanism to explain these observations was proposed. If Bt crop residues were to decompose more slowly in field soils, changes in carbon cycling and nutrient availability could result. We compared the in-field decomposition rates and diversity of decomposers colonizing residues of two Cry1Ab Bt corn hybrids, active against the European corn borer, with their non-transgenic isolines in litterbags placed in a Nebraska field. After five months, we found no significant differences in either the rates of residue mass loss or in the bacterial, fungal or microarthropod communities colonizing the transgenic versus the non-transgenic residues. Instead, both residue mass loss and detritivore colonizers were significantly affected by residue placement (surface versus buried) and plant part, demonstrating that environmental factors and residue quality, not the presence of the Cry1Ab protein, were the key drivers of residue decomposition and detritivore colonization in this study.

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Section: Bacterial and Fungal Communities Colonizing The Surface Of Csupporting

confidence: 92%

Section: Introductionmentioning

confidence: 97%

In-field rates of decomposition and microbial communities colonizing residues vary by depth of residue placement and plant part, but not by crop genotype for residues from two Cry1Ab Bt corn hybrids and their non-transgenic isolines

Londoño-R

Tarkalson²,

Thies

2013

Soil Biology and Biochemistry

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“…Sieving through 0.5-10 mm mesh sieves is used to remove fragments of litter, roots, fungal hyphae and stones, homogenizing soils in preparation for determination of microbial biomass C (C MIC ), microbial diversity, enzymatic activity, soil respiration, microbial uptake of labelled compounds and N mineralization (Devare et al, 2007;Jan et al, 2009;Nosalewicz and Nosalewicz, 2011;Jezierska-Tys et al, 2011;Thomson et al, 2010). Such preparation disturbs the natural soil pore structure with the loss of organic C when preferential flow cannot occur and heterogeneity of soil properties is reduced (ter Laak et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Increasing soil disturbance through smaller sieves (0.5-2 mm) results in greater flush of easily utilizable C and N due to the disruption of aggregates protecting soil C, and creates new surfaces, which facilitates wetting of the disturbed material, leading to increased microbial growth and functional diversity (Marinari et al, 2010). 2 mm sieves are often used to remove soil fauna (Blouin et al, 2005), while 1 mm sieves are sometimes used to separate rhizosphere soil from the roots (Devare et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Effect of soil sieving on respiration induced by low-molecular-weight substrates

Datta

Vranová

Pavelka

et al. 2014

International Agrophysics

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A b s t r a c t. The mesh size of sieves has a significant impact upon soil disturbance, affecting pore structure, fungal hyphae, proportion of fungi to bacteria, and organic matter fractions. The effects are dependent upon soil type and plant coverage. Sieving through a 2 mm mesh increases mineralization of exogenously supplied carbohydrates and phenolics compared to a 5 mm mesh and the effect is significant (p<0.05), especially in organic horizons, due to increased microbial metabolism and alteration of other soil properties. Finer mesh size particularly increases arabinose, mannose, galactose, ferulic and pthalic acid metabolism, whereas maltose mineralization is less affected. Sieving through a 5 mm mesh size is suggested for all type of experiments where enhanced mineralization of low-molecular-weight organic compounds needs to be minimalized.K e y w o r d s: sieving, carbohydrates, phenolics, amino acids, microorganisms

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“…Devare et al [191] detected no deleterious effects of growing Bt corn expressing the Cry3Bb1 protein for two consecutive seasons in the field on microbial biomass, microbial activity, or on bacterial community structure determined by terminal restriction fragment length polymorphism analysis. In a continuation of the studies of Devare et al, a 3-y field assessment of Bt corn expressing the Cry3Bb1 protein vs. near-isogenic non-Bt corn grown with and without the insecticide, tefluthrin, showed that neither the Bt corn nor the insecticide had adverse effects on microbial biomass, N mineralization potential, or rates of nitrification and respiration.…”

Section: In Situ Field Studies Of Microbial Populations and Enzyme Acmentioning

confidence: 99%

Fate and Effects in Soil of Cry Proteins from Bacillus thuringiensis: Influence of Physicochemical and Biological Characteristics of Soil

Saxena¹,

Pushalkar

Stotzky³

2013

TOTNJ

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Bacillus thuringiensis (Bt) is a useful alternative or supplement to synthetic chemical pesticides in agriculture, forest management, and control of mosquitoes and some other biting insects. When modified Bt cry genes are inserted into a plant species (e.g., corn, cotton, potato, canola, rice), the plant expresses active larvicidal proteins in its tissues. The toxins continue to be synthesized during growth of the plants, making the plant toxic to various insect pests throughout their life or as biomass incorporated into soil. If production exceeds consumption, inactivation, and degradation, the toxins could accumulate to concentrations that may enhance the control of target pests or constitute a hazard to nontarget organisms, such as the soil microbiota, beneficial insects (e.g., pollinators, predators and parasites of insect pests), and other animal classes. The accumulation and persistence of the toxins could also result in the selection and enrichment of toxin-resistant target insects. Persistence is enhanced when the toxins are bound on surface-active particles in the environment (e.g., clays and humic substances) and, thereby, rendered more resistant to biodegradation while retaining toxic activity. Moreover, major problem we face today is of "Molecular pharming" that utilizes transgenic plants and animals for production of pharmaceuticals and chemicals for their use in human beings and industries respectively. Their release to the environment, especially to soil and potentially to waters of the pharmaceutical and industrial products of transgenic plant and animal "pharms" could pose a hazard to the environment. In contrast to the products of most transgenic plants currently available commercially (e.g., the insecticidal proteins from subspecies of Bt) that primarily target insects and other pests. These "pharms" are being genetically engineered to express products for use primarily in human beings. Consequently, these products constitute a class of compounds that is seldom found in natural habitats and that primarily target "higher level" eukaryotes. Hence, they are xenobiotics with respect to the environment, and their persistence in and effects on the environment have not been adequately studied and sober risk assessments on a case-bycase basis must be made before major releases of such transgenic organisms.

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Neither transgenic Bt maize (MON863) nor tefluthrin insecticide adversely affect soil microbial activity or biomass: A 3-year field analysis

Cited by 67 publications

References 49 publications

In-field rates of decomposition and microbial communities colonizing residues vary by depth of residue placement and plant part, but not by crop genotype for residues from two Cry1Ab Bt corn hybrids and their non-transgenic isolines

In-field rates of decomposition and microbial communities colonizing residues vary by depth of residue placement and plant part, but not by crop genotype for residues from two Cry1Ab Bt corn hybrids and their non-transgenic isolines

Effect of soil sieving on respiration induced by low-molecular-weight substrates

Fate and Effects in Soil of Cry Proteins from Bacillus thuringiensis: Influence of Physicochemical and Biological Characteristics of Soil

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