A parasitic fungus infecting yellow dungflies manipulates host perching behaviour

Abstract

Direct manipulation of host behaviour by endoparasites is well known among animal eukaryotic parasitic taxa like nematodes, trematodes and acanthocephalans, but is poorly documented amongst other taxa like fungi. The insect-parasitic fungal complex Entomophthora muscae is a pathogen of adult Diptera. During the summer months in Europe and America, large numbers of housefly Musca domestica and yellow dungfly Scatophaga stercoraria succumb to the fungus. It has previously been demonstrated in house flies that Entomophthora muscae indirectly manipulates the sexual behaviour of uninfected flies to enhance transmissions to a susceptible host. The behaviour of the infected fly per se is not manipulated, however, but rather, susceptible male flies are attracted to fungus-killed cadavers by unknown fungus-related cues. In contrast, I show that, in yellow dungflies, E. muscae directly manipulates host perching behaviour causing infected dungflies to perch abnormally in a highly specific manner. This new perching position, which involves changes in perching site, body posture and orientation on the plant, appears to be designed to meet the fungus's requirements for efficient spore dispersal and host infection. The fungus-animal interaction described here is a remarkable example of a parasitic organism which manipulates the behaviour of its host: an `enslaver' parasite. Both animal (e.g. nematodes, acanthocephalans) and fungal (e.g. Entomophthora muscae, Puccinia monoica) enslaver parasites are known.