Defect Life Cycle is the Cycle thru which a defect goes starts when defect found & ends when defect is closed after ensuring its not reproduced.Defect Life cycle is related to Bug found during testing so it doesn depend on Manual & Automated Testing.
Phases of Defect Life Cycle is
1. New : When Defect disccovered.
2.Open: When defect is addressed to the developer. It may then be Rejected said to be duplicate or deferred.
3. Fix : when it is fixed or defect solved by developer.
4.Close : After defect addressed by developer it comes to Tester to Test once assured its no more a defect its is Close phase.
There are more phases to this if it is to be discussed in too details but on primary level this is the right answere.