An algorithm for estimating potential deposition of corn pollen for environmental assessment

Abstract

The safety and impact on the environment of transgenic crops are important issues, and studies have shown that pollen from transgenic Bt (Bacillus thuringiensis) corn (Zea mays L.) may kill nontarget insects. To develop an algorithm for assessing the environmental effect of transgenic crops, we arranged a field experiment in Tsukuba, Japan. Pollen dispersal and deposition were measured inside and outside a cornfield throughout the flowering period. Weather conditions such as wind speed and direction were measured at the same time. Pollen dispersal peaked 1 week after the start of flowering and continued for 12 days thereafter. The variation in daily pollen dispersal was similar at all observation points. Both pollen dispersal and deposition decreased exponentially with distance from the cornfield on all days. We estimated potential pollen deposition with a quasimechanistic model that incorporates the effects of wind direction, wind speed, and flowering intensity. The daily potential deposition was summed over the flowering period, and then the relationship between distance from the cornfield and the integrated potential deposition was estimated. It was possible to show the effective area of the environmental risk zone posed by genetically modified pollen by combining the distance/deposition relationship with the dose/response relationship derived from a laboratory assay. The algorithm described here can be applied to various wind-pollinated plants to estimate both potential and integrated pollen deposition.

Maize pollen deposition in relation to distance from the nearest pollen source under common cultivation - results of 10 years of monitoring (2001 to 2010)

“…Therefore, to characterize the intensity of pollen deposition for any season and site in a comparable way in a single figure, the total accumulated deposition over the maize flowering period must be taken as an appropriate parameter [52,[60][61][62]. Because pollen production and maize pollen release vary considerably over time, the accumulated pollen deposition over the whole flowering period is the best measure of the overall intensity of pollen deposition at each site.…”

The co-existence between transgenic and non-transgenic maize in the European Union: a focus on pollen flow and cross-fertilization

“…The approaches to study pollen dispersal in maize are (1) measurements of pollen concentrations at various distances and heights from a pollen source Bassetti and Westgate, 1994;Bateman, 1947;Brunet et al, 2003;Cervantes Martínez et al, 2001;Das, 1983;Jarosz et al, 2003;Kawashima et al, 2005;Lang et al, 2004;Pleasants et al, 2001; Raynor et al, 1972;Sears and Stanley-Horn, 2000;Westgate et al, 2003;Zangerl et al, 2001), (2) measurements of levels of cross-fertilization at various distances from a source through phenotypic traits and protein analysis (Bannert and Stamp, personal communication; Bateman, 1947;Burris, 2001;Byrne and Fromherz, 2003;Cervantes Martínez et al, 2001;Chilcutt and Tabashnik, 2004;Foueillassar and Fabié, 2003;Garcia et al, 1998;Jones and Brooks, 1950;1952;Luna et al, 2001;Ma et al, 2004; Messeguer, personal communication;Narayanaswamy et al, 1997;Paterniani and Stort, 1974;Salamov, 1940;Stevens et al, 2004) or through molecular markers (Bénétrix, 2004;Bénétrix and Bloc, 2003;Henry et al, 2003;Jemison and Vayda, 2002;Meier-Bethke and Schiemann, 2003;Melé, 2004;Messeguer et al, 2003;Ortega Molina, 2004;Stevens et al, 2004;Weber et al, 2005), and (3) calculati...…”

A system model for estimating regional cross-pollination rates between GM and non-GM rice considering actual meteorological conditions and field distributions

“…Pollen flow from GM maize has also been well studied (Jarosz et al, 2003;Jarosz et al, 2005;Kawashima et al, 2004;Sanvido et al, 2008;Ushiyama et al, 2009), because Bt (Bacillus thuringiensis) maize has high productivity due to the reduction of insect damage and because cross-pollination can occur over long distances (hundreds of meters or more). Some of the above studies in Europe were conducted in projects that aim to promote the introduction of GM crops.…”

“…At the beginning stage, field studies were intensively conducted for many crops, especially maize (Kawashima et al, 2004). Later, Ushiyama et al (2009) used a Lagrangian model to calculate maize pollen dispersion more dynamically by using experimental data.…”