Question

insert dashes where needed.
—
poaching and loss of habitat not to mention infections and respiratory viruses
are pushing african apes dangerously close to the brink of extinction.

Explanation:

To properly punctuate the sentence, we use an em dash (or en dash in some cases, but em dash is more appropriate here for an aside) after "habitat" to set off the phrase "not to mention infections and respiratory viruses" as an additional comment or aside.

Step1: Identify the phrase to set off

The phrase "not to mention infections and respiratory viruses" is an aside that adds more information about what is pushing African apes to extinction.

Step2: Insert the dash

Insert a dash after "habitat" to separate the main clause from the aside.

Answer:

Poaching and loss of habitat — not to mention infections and respiratory viruses — are pushing African apes dangerously close to the brink of extinction.