Freshman pitcher Meme Quinn, starting her first college game, spread 12 hits over seven innings for the Bearkats, taking the loss.
Dumezich struck out nine Bearkats to up her season record to 6-4.
Third baseman Shelbi Tucker led off the bottom of the second inning with a double, was sacrificed to third base then scored on a sacrifice fly by right fielder Erin Burford to account for the Bearkats' lone run.
Head coach Bob Brock was pleased with the effort that Quinn showed against the Aggies.
"I thought that it was time for her to start," Brock said. "A&M's got all-Americans in the lineup and she did really good."
We were really excited about playing them (A&M) here," Quinn said. "Everyone came out real focused and ready to play."
The Bearkats will travel to Austin this week to face the University of Texas in a three-game series.