@conference{1,
abstract = "The use of Genetically modified varieties (GMV) dates back to 1997 and spreads to 26 countries out of which 18 are recording more than 50,000 ha and 11 more than one millions hectares. According to ISAAA (International Service for the Acquisition of Agri-biotech Applications), the sole source of stats related to the use of GM varieties, the total acreage covered has been increasing continuously over the period of twenty years, as well as the number of countries concerned. This quantitative evolution is claimed to be a clear indication of the global positive impacts of the use of GM varieties. This criterion is complemented by other claims related to the global decrease of the pesticides use, global production increase and economic gain and reduction of greenhouse gas emission.
The positive impacts claimed at global level are encountered also at the individual level of a country such as Australia. The country specificity of high yield has been preserved. The savings in the insecticide use is claimed to be the most positive impact  of GMV use. This savings resulting from GMV use is illustrated by the reduction of the amount of active ingredient per hectare, but the shift to new generation of insecticide ingredients which are effective at much lower dosage has contributed as well, if not more than the GMV use. 
There are nevertheless negative impacts which are well documented and which used to be overlooked by those who advocate a further extension of the use of GMV. Where pest resistant GMV are used, the pest complexes have shifted and have implied the need to chemically control pests whose earlier infestation level did not require. Where herbicide tolerant GMV have been used (mainly tolerant to glyphosate), glyphosate resistant weeds have emerged, with a continuously increasing number of weed species. The resulting increase of the pesticide control cost, along the high and increasing cost of seeds, has implied a reduction if not a reversion of the profitability in using GMV. Australia is a rare exception of country where the mentioned negative impacts are not documented, thanks to a particular coordination among  a small total number of cotton growers (around 1,000), which nevertheless has not prevented them to pay the highest fees for the right of using GMV.
Lessons from the effects observed are fourfold. First, it is worth debating again the issue of effectiveness of the genes used so far in GMV, by distinguishing short term and mid-term effects, as the effects could reverse 5-6 years after the commercial release of the varieties. Second, the assessment of the impacts of GMV which overlooks distinct short term and mid-term effects, as those commonly implemented globally or at the level of a country, does not help to capture reality and could be misguiding. Third, the ecosystem reacts to the way GMV are being used; the pest complex shift and the emergence of weeds resistant to herbicides are illustrations of ecological reactions to the mis-management of GMV use based on general and continuous use. Fourth, if GMV were to be used, the best way is partial use.  
",
author = "Michel FOK",
booktitle = "13th Meeting of the Inter‐regional Cooperative researche network on cotton for the Mediterranean and Middle East regions. Luxor, Egypt. February 2018",
title = "Twenty years of GM varieties use: Lessons learnt",
url = "http://www.slire.net/download/2639/2018_luxor_20y_gm_ful.pdf",
year = "2018"
}