Data from: Do scavengers prevent or promote disease transmission? The effect of invertebrate scavenging on Ranavirus transmission

1. Host-parasite interactions are shaped by the broader web of community
interactions, from interspecific competition to predator-prey dynamics.
Heterospecific scavengers might also affect parasite transmission from
infectious carcasses, which can be an important source of infections for
some wildlife diseases. 2. A robust scavenger community can quickly remove
carcasses and tissue and thus prevent secondary transmission by necrophagy
or contact with infectious carcasses. Alternatively, by spreading
infectious particles and tissues throughout the environment, scavengers
may increase rates of casual contact with pathogens and thus overall
transmission. However, there has been little empirical consideration of
the contrasting roles that scavengers might play in infectious disease
dynamics. 3. We carried out a series of studies to determine the
efficiency with which scavenging invertebrates remove carcasses of
Long-toed Salamander (Ambystoma macrodactylum) larvae and their role in
the transmission of Frog Virus 3 (Genus: Ranavirus, Family: Iridoviridae)
from carcasses. We then estimated the functional response of one efficient
invertebrate scavenger (Family: Dytiscidae) to increasing carcass
densities in field conditions in order to determine the capacity of
scavenging invertebrates to consume large amounts of carcass tissue, as
may be present at high prevalence sites. 4. We found that removal of
infectious carcasses by scavengers strongly reduced transmission to naïve
larvae. Scavengers were as effective at reducing transmission from a
carcass as a physical barrier preventing contact with the carcass. There
was little evidence that scavenging released sufficient infectious tissues
into the water column to rival direct contact as a route of infection.
Moreover, while scavenging rates saturated at increasing carcass
densities, consistent with a type II functional response, there were
sufficient densities of dytiscid larvae, not to mention other scavenging
invertebrates, in a surveyed pond to theoretically prevent transmission
from carcasses. 5. Our results suggest that at least in systems in which
conspecific necrophagy is common, the scavenger community can play an
important role in reducing transmission.