THIRD WORLD NETWORK BIOSAFETY INFORMATION SERVICE
Dear Friends and Colleagues
Maize farming in Africa is vulnerable to uncontrolled spread of genetically modified varieties
A new publication from GenØk-Centre for Biosafety, Norway shows that maize farming by smallholders in Africa, for local food production, is particularly vulnerable to the introduction of genetically modified (GM) maize. The reason is that the fields are situated very close to each other (distance often 2-5 m) and that pollen will cross-hybridize at a high rate. In addition, farmers recycle their seeds year after year and share seeds with neighbors and family. This increases gene flow locally, but also increases the distance that genes travel. Seed sharing may transfer viable seeds up to 100 km.
The study performed fieldwork in Zambia, uses mathematical modelling of pollen spread and interviewed farmers about their seed management practices. Globally, 85 % of all farms are small-scale (< 2ha).
The study concludes that segregation of GM and non-GM maize varieties is likely not an option in these systems. If GM maize is introduced, the probability of uncontrolled spread of GM maize is high. One further negative effect is that cross-hybridization of Bt-maize and non-GM maize may give increased risk of resistance development in pest insects.
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Pollen-mediated gene flow and seed exchange in small-scale Zambian maize farming, implications for biosafety assessment
By Thomas Bøhn, Denis W. Aheto, Felix S. Mwangala, Klara Fischer, Inger Louise Bones, Christopher Simoloka, Ireen Mbeule, Gunther Schmidt & Broder Breckling
The article is available online: http://www.nature.com/articles/srep34483
Abstract: Gene flow in agricultural crops is important for risk assessment of genetically modified (GM) crops, particularly in countries with a large informal agricultural sector of subsistence cultivation. We present a pollen flow model for maize (Zea mays), a major staple crop in Africa. We use spatial properties of fields (size, position) in three small-scale maize farming communities in Zambia and estimate rates of cross-fertilisation between fields sown with different maize varieties (e.g. conventional and transgene). As an additional factor contributing to gene flow, we present data on seed saving and sharing among farmers that live in the same communities. Our results show that: i) maize fields were small and located in immediate vicinity of neighboring fields; ii) a majority of farmers saved and shared seed; iii) modeled rates of pollen-mediated gene flow showed extensive mixing of germplasm between fields and farms and iv) as a result, segregation of GM and non-GM varieties is not likely to be an option in these systems. We conclude that the overall genetic composition of maize, in this and similar agricultural contexts, will be strongly influenced both by self-organised ecological factors (pollen flow), and by socially mediated intervention (seed recycling and sharing).
For further questions or information contact:
Thomas Bøhn (PhD), GenØk
thomas@genok.org
phone +47 97 00 99 16