.net - Can QA be efficient without Unit-testing (TDD)? -

a company has small dev teams on few countries.
during few years releases software product (client in ms visual studio 2008 c++, c# , server in java) based on mathematic , cross-branch engineering fundamental sci (and high-tech) researches.
software development not based on tdd (test-driven development), there no unit-tests, qa department, etc.

this company initiates introduction of qa group (department and, well, qa practices/policies) of 2-3 persons.

the first priority tasks establish (automated) testing practices of gui , api.

is introduction of unit (or mock) testing or tdd(test-driven development) essential , obligatory success of qa?

update:
database storage ms sql server.

update2:
posted http://testing.stackexchange.com/questions/791/what-are-in-qa-besides-testing

i understand after-the-fact unit-tests (or, rather, mock) should incorporated recurring bugs should first issue introduce?
possible first priority issues , orders? should after-the fact unit-tests introduced developers or "testers"?

can qa possibly efficient without unit- (mock-) testing @ all?

update3:
comment tdd not unit-testing, started read:

• tdd vs. unit testing (so)
• should use tdd?
• test driven development vs "plain old unit
• disadvantages of test driven development?
• tdd tests not unit tests

asked after having read:

• pro's , con's of unit testing after fact.
• a unit testing walkthrough visual studio team test
• pro's , con's of unit testing after fact.
• when time have qa department?
• unit tests qa engineer
• role of testers in agile?
• what single best open source automation tool functional web testing
• open source tool stress testing, load testing , performance testing
• tools automated gui testing (on windows)?
• gui testing
• automate builds in .net
• measuring class dependencies

as stated in comment above, tdd not same unit testing.

my advice:

having been in similar situation before (i founding qa-er @ company till point had no formal qa methods), stress need make sure qa process non-invasive programming processes.

if developers used tdd methodologies might easy implement tdd, based off information sounds implementing tdd slow down development (at least till got used it).

if wanting baby step things suggest unit testing. that's implemented when called same task, , on time introduced other things.

answers:

qa can effective without structured unit testing depending on quality of persons performing qa duties. qa more efficient when there structured unit tests can follow.