Journal or Publishing Institution: Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft
Date of Publication: 01/01/2007
Author(s): Büchs, W., Raubuch, M., Prescher, S., Behr, K., Müller, A., and Roose, K.
Article Type: Study
Abstract:
Field and laboratory experiments with two transgenic Ostrinia-resistant-Bt-maize varieties (‘Novelis‘ event Mon810 and ‘Valmont’ event Bt 176) and the two corresponding conventional isolines (‘Nobilis’ and ‘Prelude’) were conducted in Germany. As decomposers microbial communities and larvae of saprophagous Diptera were taken into consideration.
During the growth phase of soil microbial communities the addition of transgenic maize straw increased respiration rates and specific respiration (qCO2 and CO2-to-ATP ratio) significantly compared to the addition of conventional maize straw. The energy production from respiration was twice as high in soils treated with transgenic varieties, but the energy could not be used for growth or energy store in ATP and ADP. The data indicate that the addition of maize caused a fast reaction of ‘r’-strategists which are wasteful with energy and that Bt-maize especially caused additionally a kind of stress. It could be shown that detoxification took place. Laboratory feeding tests with Lycoriella castanescens (Diptera: Sciaridae) with litter of Bt-Mon810 “Novelis” showed in comparison to its isogenic partner cultivar “Nobilis” and another conventional cultivar “Eurostar” a significant longer period until pupation. Additionally, trials were conducted in which Sciaridae-larvae which were raised exclusively either with Bt-Mon810 “Novelis” or the isogenic partner “Nobilis” (with and without insecticide treatment) and afterwards offered as prey to predacious rove beetle Atheta coriaria (Coleoptera: Staphylinidae) and ground beetle Poecilus cupreus (Coleoptera: Carabidae). Even in these trials a considerable delay of larval development of the predators could be observed when they exclusively preyed on Sciaridae-larvae which were fed with Bt-Mon810-“Novelis” maize-litter: Although they fed more Sciaridae-larvae raised with Bt-Mon 810-litter P. cupreus- as well as A. coriaria –larvae needed significant more days until they start to pupate.
It is highly striking that micro organisms, invertebrate decomposers as well as invertebrate predators which represent different levels of the food chain show very similar reactions to Bt-maize. Obviously (Mon810-) Bt-maize consumption induces detoxification procedures which require a high input of energy which however cannot be used to increase biomass so that growth is reduced and – in consequence – larval development are delayed. It is basic knowledge that in case of stress as e.g. detoxification the respiration rate of mitochondria increases and in consequence – caused by some processes in between – cells are not able to synthesise ATP anymore. At least it reduces fitness which potentially might affect reproduction success and thus population development. These possible risks of Bt-maize are discussed in respect to impacts on ecological processes and ecosystem functions as well as in respect to consequences for the commercial growing of Ostrinia-resistant Bt-maize and the design of test procedures.
Keywords: genetically modified crops, Bacillus thuringiensis, var. kurstaki, Bt maize, Bt corn, soil microorganisms, soil microbiome, respiration rate, decomposers, Diptera-larvae, Sciaridae, predators, ground beetles, rove beetles, Carabidae, Staphylinidae
Citation:
Büchs, W., Raubuch, M., Prescher, S., Behr, K., Müller, A., and Roose, K., 2007. Impact of Ostrinia-resistant Bt-maize on microbial and invertebrate decomposer communities in field soils. Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft, 410, 26-32.
Category:
- Environmental effects
- Pesticide use
Record ID: 273
