One of the colonists informs Shepard that the food supply of Zhu's Hope is running low. If Shepard goes to investigate, a bunch of varren will confront the crew. After killing all the varren, the alpha male makes its appearance.
Because the Varren Alpha is tougher than the average varren, it will charge faster and hit harder. It can kill in just a few hits with its massive bite, so remember to keep moving and use your squad members to aid you. Singularity and Lift are helpful in dealing with the Varren Alpha and other varren accompanying it.