Occurrence of maize detritus and a transgenic insecticidal protein (Cry1Ab) within the stream network of an agricultural landscape

Abstract

Widespread planting of maize throughout the agricultural Midwest may result in detritus entering adjacent stream ecosystems, and 63% of the 2009 US maize crop was genetically modified to express insecticidal Cry proteins derived from Bacillus thuringiensis. Six months after harvest, we conducted a synoptic survey of 217 stream sites in Indiana to determine the extent of maize detritus and presence of Cry1Ab protein in the stream network. We found that 86% of stream sites contained maize leaves, cobs, husks, and/or stalks in the active stream channel. We also detected Cry1Ab protein in stream-channel maize at 13% of sites and in the water column at 23% of sites. We found that 82% of stream sites were adjacent to maize fields, and Geographical Information Systems analyses indicated that 100% of sites containing Cry1Ab-positive detritus in the active stream channel had maize planted within 500 m during the previous crop year. Maize detritus likely enters streams throughout the Corn Belt; using US Department of Agriculture land cover data, we estimate that 91% of the 256,446 km of streams/rivers in Iowa, Illinois, and Indiana are located within 500 m of a maize field. Maize detritus is common in lowgradient stream channels in northwestern Indiana, and Cry1Ab proteins persist in maize leaves and can be measured in the water column even 6 mo after harvest. Hence, maize detritus, and associated Cry1Ab proteins, are widely distributed and persistent in the headwater streams of a Corn Belt landscape.genetically modified crops | crop detritus | ELISA | rivers

Agricultural land use alters the seasonality and magnitude of stream metabolism

“…detritus and grasses (Menninger and Palmer 2007;RosiMarshall et al 2007;Griffiths et al 2012a); however, unlike leaf fall, which is fairly predictable, inputs of crop detritus are sporadic and are driven by the dynamics of wind and overland flow Jensen et al 2010;Tank et al 2010) and do not appear to be pulsed in such a way as to elicit a strong temporal response in ER. In addition, input of senescent grasses occurs in late autumn, but live grasses slump into and decompose within streams throughout the year (Menninger and Palmer 2007) and may be a temporally consistent allochthonous resource to agricultural streams.…”

Scientific Opinion on an application from Pioneer Hi‐Bred International and Dow AgroSciences LLC (EFSA‐GMO‐NL‐2005‐23) for placing on the market of genetically modified maize 59122 for food and feed uses, import, processing and cultivation under Regulation (EC) No 1829/2003

“…By-products from GM plants (e.g., pollen, detritus) can be transported in water courses to downstream water bodies where non-target aquatic arthropods can be exposed to transgene product(s) through consumption (Axelsson et al, 2010(Axelsson et al, , 2011. In the case of Bt-maize, Rosi-Marshall et al (2007) reported that by-products of Bt-maize enter headwater streams in the United States and claimed, on the basis of experimental data obtained under lower-tier conditions, that this would reduce growth and increase mortality of some non-target aquatic arthropods, especially trichopteran species (see also Chambers et al, 2010;Tank et al, 2010).…”

Bt Crops: Past and Future

“…While deposition of Bt plant tissue in the proximity of streams by wind and surface runoff can result in leaching of Bt toxins in the water (Tank et al 2010;Viktorov 2011), their insecticidal properties on aquatic insects have not been demonstrated. The effect of transgenic Bt crop detritus on aquatic ecosystems should be comprehensively explored.…”