Terrain and laboratory research were conducted to determine the potential of Gastroidea viridula Deg. (Coleoptera: Chrysomelidae) to control mossy sorrel (Rumex confertus Willd.). In a field study, the dynamicof plant biomass and number of larvae occurring on that plant were investigated. The Pearson’s linear correlation coefficient of biomass increase in time equalled, to r = 0.96. The regression equation showed, that the plant daily growth reached 29 g; and 210 g per week, consequently. In the laboratory, weight of consumed food by larvae, and larval body weight were measured at 20°C. First generation of G. viridula was taken into consideration. Total weight of consumed leaves by all three instars of a single larva, during 50 days of the development amounted to 1.243 g. Also seasonal abundance of larvae was observed. On May 25th the highest observed number of G. viridula larvae per plant ranged from 435 to 469 individuals. This species may be of usefulness in biological control of mossy sorrel.

Weeds are harmful organisms connected with human activities; therefore there is a need for their control. human development and mobility have caused on purpose or purely incidental introduction of plants, exotic very often, to new sites and ecosystems. A dominating method of weed control is applying chemicals. However, chemical compounds are often of low selectivity, they also contaminate the environment and become ineffective quickly because of acquired resistance of treated organisms. The control of Rumex confertus Willd. and other weeds of the genus Rumex spp. is often not possible because of economical reasons. Large areas abundant in sorrel populations would require a large sum of money invested in expensive chemical control. Biological methods of weed control look far more promising solution to this problem. Rumex confer/us Willd. is a plant corresponding to criteria to qualify it as an object for biological regulation. The objective of the study was to evaluate dynamic of population and development of the insects of the genera Gastroidea spp. (Gastroidea viridula Deg. and Gasrroidea polygoni L.) occurring on Rumex confertus Willd.