Phratora

Phratora species are found in the Northern Hemisphere in areas that tend to be cool and moist where their host plants thrive.^[4] They are usually found in Northern and Southern Europe,^[3] China and Japan,^[5][6][7] and in Canada and the United States of America.^[8][1]

Species in this genus are of considerable interest to evolutionary ecology researchers because they vary with respect to host plant preference and chemistry of their larval defensive secretions.^[8] Phratora species are known to feed on willows (Phratora americana, P. frosti, P. interstitialis, P. tibialis, Phratora vitellinae, Phratora vulgatissima, P. polaris, P. purpurea), poplars (Phratora laticollis, P. atrovirens, Phratora vitellinae, P. purpurea), or birch (P. polaris in Lapland, Phratora hudsonia), and their host plant use is evolutionarily conserved in that closely related beetle species tend to feed on more closely related plant species.^[8][9]

Predators of Phratora eggs include A. nemorum, Orthotylus marginalisand the syrphid fly Parasyrphus nigritarsis.^[10] Larval predators include A. nemorum, the bug Rhacognathus punctatus,^[10] and the wasp Symmorphus bifasciatus.^[11] Adult beetles are consumed by R. punctatus.^[10] More information about natural enemies can be found in the articles about Phratora laticollis, Phratora vitellinae and Phratora vulgatissima.

The mechanism of larval defensive secretion production, its relationship to host plant preference, and its evolutionary significance has been studied.^[12][13] The secretions can repel natural enemies or conspecifics.^[14] More information about larval secretions can be found in the articles about Phratora laticollis and Phratora vitellinae.

Some species (especially Phratora vulgatissima) are considered pests when populations build up in willow plantations.^[15]

These 16 species belong to the genus Phratora:

Data sources: i = ITIS,^[16] c = Catalogue of Life,^[17] g = GBIF,^[18] b = Bugguide.net^[19]