While insect-resistant genetically modified crops decreased pesticide use by 16 million pounds here, herbicide-tolerant GMOs increased pesticide use by 138 million. The net result? 122 million more pounds, not less, of pesticides used in the U.S. alone.
Source: "Genetically Engineered Crops and Pesticide Use in the United States: The First Nine Years," Charles Benbrook, Technical Paper No. 7, October 2004