Movie S1.

Behavioral repertoire of low-level–infected ants displayed toward a contaminated nestmate. L. neglectus workers that had previously acquired low-level infections by social contact with an exposed individual were observed for their behavior toward a newly encountered, contaminated nestmate (red color marking), from which they could contract either the homologous or the detrimental, heterologous pathogen. Displayed behaviors: (i) four low-level–infected ants removing infectious particles from the body surface of their contaminated nestmate by grooming, (ii) a low-level–infected ant disinfecting a contaminated nestmate by antimicrobial poison spraying (two examples), and (iii) a low-level–infected ant performing aggressive behavior (dragging) against a contaminated nestmate (two examples). Still image from Movie S1: In the upper right a low-level–infected L. neglectus worker disinfects its pathogen-contaminated nestmate by antimicrobial poison spraying [i.e., by bending its rear end (gaster tip) with the poison gland exit toward the contaminated nestmate].