1. Laboratory of Biotic Interactions, Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico
2. Laboratory of Soil Ecology, Cinvestav, Mexico City, México
3. International Maize and Wheat Improvement Centre (CIMMYT), El Batán, Texcoco, México
4. Cornell University, Ithaca, New York, USA