Differential survival rates of damselfly larvae in the presence of newt and dragonfly predators


The damselfly species Paracercion melanotum has been found to be the most abundant species in damselfly larval communities on Okinawa-zima Island in southwest Japan. To clarify differential susceptibility to predation, a possible factor affecting relative population densities in larval communities, between Paracercion melanotum and a less common damselfly species, Ischnura senegalensis, laboratory experiments were conducted using three abundant predator species: the sword-tailed newt (Cynops ensicauda popei), anisopteran larvae (Crocothemis servilia servilia), and a planktivorous fish (Poecilia reticulata). Paracercion melanotum survived predation by the newt and the dragonfly well compared to I. senegalensis. Fishes consumed approximately equal numbers of the two damselfly species. From these results, the newt and the dragonfly were suggested as the most probable predators regulating damselfly larval communities on Okinawa-zima Island. Predators could be a crucial factor determining relative abundance in damselfly larval communities.

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