The chrysomelid beetle Gastrophysa viridula was formerly restricted to alpine regions, but now it has expanded its distribution to northern, middle, and eastern Europe. In North America this species is replaced by G. formosa. The oligophagous beetles are found on Polygonaceae, mostly Rumex plants but also on Rheum, and were reported to be a pest on vine in Arizona. The 4 to 6 mm long beetles are metallic green with a black ventral side. Females with eggs are easy to distinguish from males by their swollen abdomen. The eggs are deposited in batches of 20 to 45 on the underside of leaves. The emerging larvae moult two times. The developing time from egg to the adult beetle takes about 50 days (eggs: 7-10, larvae: 21-30, pupae: 6-9 days). Normally, Gastrophysa produces three generations per year. Adults of the autumn generation enter diapause up to the next spring.
Rearing conditions We rear the stock culture of beetles under a 16:8 (l:d) light regime with a temperature of 20° C and a relative humidity of 50% in a climate chamber (Rubarth Apparatus 3201). Twenty to 30 beetles are placed in Petri dishes of 12 cm diameter. The dishes are covered with paper pulp, and the beetles are fed daily with fresh Rumex leaves. The newly emerged animals start to copulate after 3 days and deposit the first eggs after 5-7 days. Larvae get Rumex leaves up to the end of the third stage. Thereafter they stop feeding and seek deeper places in the paper sheets. The pupae are extremely sensible against touching and they should not be disturbed.
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