Feeding in the two phytophagous beetles Hydromedion sparsutum and Perimylops antarcticus from South Georgia

Abstract

The consumption of fresh plant materials by adults and larvae of Hydromedion sparsutum and Perimylops antarcticus (Col., Perimylopidae) was estimated from the production of faecal pellets and amount of excreted plant remnants as dry weight. Adults and larvae of Hydromedion consumed large quantities of grasses, including the alien Poa annua, but smaller amounts of the indigenous great burnet, Acaena magellanica. Both stages of Perimylops consumed much smaller quantities of grasses and Acaena. Different species of mosses were eaten in both species, and appeared to be a major source of food for Perimylops in addition to microphytes on rocks. The consumption of mosses and microphytes reflects the adaptation of Perimylops to living in habitats at higher altitudes (e.g. above 200 m), where other plants are scarce.