She and her colleague[2] from the International Maize and Wheat Improvement Center (CIMMYT), Surinder Vasal, shared the 2000 World Food Prize for this achievement.
Villegas was in charge of the lab investigating protein quality, while Vasal worked on developing QPM varieties that would gain widespread acceptance.
Villegas and Vasal together combined existing "opaque-2" maize variety using molecular biology techniques.
She would also be involved in the establishment of quality laboratories in India, Thailand, Egypt, Tunis, Ghana, the Philippines, Peru, Ecuador, Colombia, Bolivia, and Mexico.
[7] The chemical and analytical approaches she developed continue to aid the CIMMYT in their work to monitor protein quality in QPM.