On colour variability of the common green grasshopper Omocestus viridulus (Orthoptera: Acrididae) in northwestern Russia

Abstract

The diversity of colour forms in the common green grasshopper Omocestus viridulus (Linnaeus, 1758) in 19 localities of the Leningrad, Novgorod and Pskov provinces and adjacent districts of the Vologda and Tver provinces is studied. It has been established that the common green grasshopper is represented by three colour forms: rubiginosa (top and sides of brownish or greyish tones), hyalosuperficies (green top, greyish or brownish sides) and viridis (green top and sides). The most characteristic form for males is rubiginosa, for females is hyalosuperficies, while females of the form rubiginosa and (especially) males of the hyalosuperficies form are extremely rare. The proportion of specimens of the form viridis does not depend on sex, does not depend on the natural zone in which the locality is situated, and nowhere exceeds a quarter of the total number of recorded specimens. To the east of the conventional line passing through the town of Chudovo and the settlement of Kresttsy, Novgorod Province, individuals of the form viridis are practically not found, there is only a single record of such a male. At the same time, the representation of the form viridis on different sides of the above-mentioned line is statistically significantly different. The data obtained are consistent with the results of our previous study carried out at 10 localities in the Novgorod and Pskov provinces. In addition, in terms of the representation of the form viridis, our data for northwestern Russia differ statistically significantly from the literature data published in the 1940s for the Scandinavian and British populations of the same species.