From APA Lite (see related link):
"Use italics (or underline) for the titles of books, species names, novel or technical terms and labels (the first time only), words and phrases used as linguistic examples, letters used as statistical symbols, and the volume numbers in references to journal articles.
From The OWL at Purdue (see related link); also see this site for examples of reference entries:
No, websites are not italicized in APA format.
Abbreviations allowed in APA format are acronyms.
Yes, articles are italicized in APA format.
Yes, titles are italicized in APA format.
Yes, the title is italicized in APA format.
Yes, I can write your paper in APA format.
In APA format, articles are italicized, not quoted.
Yes, in APA format, book titles are italicized.
No, website names are not italicized in APA format.
Yes, the edition should be italicized in APA format.
In APA format, 11 is almost always written as 11.
Yes, article names are italicized in APA format.