I came here with a similar question, but looked into the sources @bwiernik suggested and confirmed. Here's a clearer explanation for whoever might have the same question:

"As you can see in the table above, the titles of works that stand alone (such as a book or a report) are italicized in both the text and the reference list. In contrast, the titles of works that are part of a greater whole (such as an article, which is part of a journal, or a book chapter, which is part of a book) are not italicized in either place, and only in the text are they put inside quotation marks. If you are having difficulty determining whether something stands alone (such as a webpage that may or may not be part of a greater website), choose not to italicize." (Source: http://blog.apastyle.org/apastyle/2012/03/how-to-capitalize-and-format-reference-titles-in-apa-style.html)