Although APA rules are applicable to papers in almost any field, there are some peculiarities of the use of APA in biology. Here, names of species, bacteria varieties, and genera are italicized.

Examples:

Clostridium difficile

Homo sapiens

As for references, duch names are italicized in the title as well:

Lessa, F. C., Mu, Y., Bamberg, W. M., Zintars, G., Beldavs, M. S., Dumyati, G. K., … McDonald, L. C. (2015). Burden of Clostridium difficile infection in the United States. The New England Journal of Medicine, 372, 825-834. doi: 10.1056/NEJMoa1408913

For further information on how to cite articles, see the link https://eessays.co/2019/04/13/apa-style-for-articles/