Adaptation
As stated before, Ophiocordyceps camponoti-balzani is the entomopathogenic fungus Ophiocordyceps unilateralis which specifically infects carpenter ants from the Camponotini tribe. Originally thought to be a single species, studies have revealed carpenter ants in Thailand, Africa and Brazil are all capable of becoming infected.
Directing the ant to a prime location, and forcing the ant to bite on the underside of a leaf is an adaption of the fungus to increase its parasite fitness. Positioning the ant will allow fungal growth, and spore disbursement which will help the fungus to complete its life cycle.