Table 1.

Manipulation of host behavior by parasites from multiple levels of biotic organization

Biotic level	Example	Host	Deceptive strategy	Type of deceptive signal	Effect on host behavior
Virus	Rabies lyssavirus (rabies)	Bats	Rabies glycoprotein is a molecular mimic of acetylcholine and binds to nicotinic acetylcholine receptors (Rustici et al. 1993)	Molecular	Symptoms of rabies infection include hydrophobia, anxiety, hyperactivity, aggression and fearlessness (Bano et al. 2016)
Protozoan	Toxoplasma gondii (toxoplasmosis)	Cats	Parasite tyrosine hydroxylase mimics the activity of the host enzyme, increasing the amount of dopamine present in the brain	Molecular	(In rats) increase in exploratory behavior, decrease in neophobia and fear of cats, its primary host (Webster 2007). This is linked with increased dopamine
Fungus	Ophiocordyceps unilateralis	Ants	Guanidinobutyric acid and sphingosphine are secreted by the fungus and may affect ant behavior (de Bekker et al. 2014)	Molecular	The infected ant climbs to the tip of a leaf, and then clamps its jaws on it until it dies. Then the fungus bursts out of the head of the ant and spreads its spores
Invertebrate	Hairworm (Spinochordodes tellinii)	Grasshoppers	Parasite produces Wnt proteins that appear to be molecular mimics of host proteins (Biron et al. 2005)	Molecular	The hairworm causes the grasshopper to commit suicide by drowning, promoting spread of parasite larvae
Vertebrate	Cuckoo	Nesting birds	Cuckoo chick mimics host chicks, including begging behavior	Visual and auditory	Host bird diverts resources to feed the cuckoo chick. The chick gape is a stimulus that induces the host birds to supply it with food
Human	Psychopaths (described as 'social parasites' (Karpman 1949))	Non-kin members of same species	Affective mimicry (the mimicry of emotions) (Book et al. 2015)	Visual and verbal	Victims are deceived into thinking the psychopath is trustworthy