Referencing others' ideas in introductions and conclusions?
If I understand your question, you're asking whether statements in an introduction or conclusion which summarise fully-referenced, more detailed statements in the body of your writing should be referenced too.

The answer is the same as for anything, regardless of where it's found in something you write:

If a statement is your own conclusion based on information you have drawn from outside sources, then as long as you note what information you got from which sources by referencing correctly within the body of the document where you explain how you came to your conclusion, you don't need to reference this conclusive or interpretive statement; it's the result of your own mental process.

On the other hand, if the statement is information from another source, you must reference it. Whether or not it's heavily summarised or you intend to expand on the statement, with references, later, the simple rule of referencing everything that did not originate with your own work still applies.

As a rule, though, I'd advise you to check with your teacher, tutor, student advisor, TA, lecturer, or whomever else applies. What I explained above is technically the right way to do it, but it wouldn't surprise me if some institutions at least aren't quite that strict.