Sampling Strategies for Evaluating the Rate of Adventitious Transgene Presence in Non‐Genetically Modified Crop Fields

Abstract

According to E.U. regulations, the maximum allowable rate of adventitious transgene presence in non-genetically modified (GM) crops is 0.9%. We compared four sampling methods for the detection of transgenic material in agricultural non-GM maize fields: random sampling, stratified sampling, random sampling + ratio reweighting, random sampling + regression reweighting. Random sampling involves simply sampling maize grains from different locations selected at random from the field concerned. The stratified and reweighting sampling methods make use of an auxiliary variable corresponding to the output of a gene-flow model (a zero-inflated Poisson model) simulating cross-pollination as a function of wind speed, wind direction, and distance to the closest GM maize field. With the stratified sampling method, an auxiliary variable is used to define several strata with contrasting transgene presence rates, and grains are then sampled at random from each stratum. With the two methods involving reweighting, grains are first sampled at random from various locations within the field, and the observations are then reweighted according to the auxiliary variable. Data collected from three maize fields were used to compare the four sampling methods, and the results were used to determine the extent to which transgene presence rate estimation was improved by the use of stratified and reweighting sampling methods. We found that transgene rate estimates were more accurate and that substantially smaller samples could be used with sampling strategies based on an auxiliary variable derived from a gene-flow model.

Effectiveness of different sampling schemes in predicting adventitious genetically modified maize content in a smallholder farming system

“…8 Some researchers use different pollen dispersal models to predict the number of GM grains among the non-GM maize ears in a field. [9][10][11][12] An efficient and accurate sampling method can provide a confident estimate of GMO content with a small cost for monitoring.…”

“…11 To investigate the suitability of sampling schemes for GM crop monitoring, simple random sampling (SRS) is usually compared with different sampling methods. 7,9,11 Allnutt et al 9 compared four sampling plans with SRS for their ability to predict the GM levels across two transects, four transects, cross transects, and the JM method in several fields at the landscape level. The two-transect sampling had the lowest accuracy and required the smallest sample size, whereas SRS sampling had the highest accuracy and required the largest sample size.…”

“…Several studies developed different field sampling strategies combined with the dispersal function to predict CP rate for control and monitoring purposes. 7 , 9 , 11 They also compared the accuracy of different sampling methods.…”

Risks of Pollen-Mediated Gene Flow From Genetically Modified Maize During Co-Cultivation With Usual Maize Varieties

“…Согласно этой модели, для 1 га неГМ-поля, окруженного со всех четырех сторон ГМ-полями, достаточно 12 м пограничных рядов в сочетании с 12 м полосы под паром для обеспечения порогового значения 0,9 % (на 95 % уровне значимости), установленного ЕС (9). На основе сравнения четырех методов оценки наличия ГМ-кукурузы на полях неГМ-реципиентов с математической обработкой результатов был предложен более надежный способ регистрации ГМскрещиваний по всей глубине поля (36).…”

“…га). С 2005 года ГМ-сорта кукурузы возделывались в Чешской Республике, Словакии, Франции, Германии, Португалии (36). Однако с 2008 года Франция запретила выращивать ГМ-сорт кукурузы MON810, устойчивый к насекомым-вредителям (33).…”