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:

Dashes set off the parenthetical phrase "not to mention infections and respiratory viruses" to emphasize this additional set of threats, separating it from the main clause for clarity.

Answer:

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