Trophic Interactions: Similarity of Parasitic Castrators to Parasitoids

Abstract

An analysis of life history features of insect parasitoids and crustacean parasitic castrators suggests that these are similar trophic phenomena, distinct from parasitism and predation. A parasitoid consumes only one host during its lifetime; parasitic castrators cause the reproductive death of only one host. Since population densities of many insect species are regulated by parasitoids, parasitic castrators may also play an important role in host population regulation. Parasitoids of insects and parasitic castrators of crustaceans (1) in single infections always kill the host; whereas lone parasites do not affect host viability; and predators kill many prey; (2) do not cause increasing pathology or increasing likelihood of mortality in multiple infections; whereas parasites often have an additive impact; (3) do not cause increasing damage in mixed species infections; whereas mixed parasite infections often have interactive negative effect; (4) Usually have mechanisms to reduce or eliminate multiple infec...