Galitsky A.V., Dzhonson N.P., Antipov A.V., Gilev A.V. Long-term variability in the pronotum pattern of the Colorado potato beetle Leptinotarsa decemlineata Say (Coleoptera, Chrysomelidae) in the Middle Urals

Abstract

Populations of the Colorado potato beetle exhibit by a high level of polymorphism, which enables them to have high ecological plasticity and quickly adapt to various conditions. Our research examines the variability of the pattern of the central part of the pronotum of the Colorado potato beetle Leptinotarsa decemlineata in samples collected from two localities of the Middle Urals over several years. New variants of the pattern are described, which have not been previously observed in the European part of the Russian Federation. Higher degree of melanization is typical for these variations. Furthermore, these variants are characterized by the merging of the central stripes with each other and with the lower spot. In the populations of the Middle Urals, variants 1–3 dominated with a cumulative frequency of occurrence of 32–55 %; and a new variant a was found in significant quantities (5–12 %). In total, the frequency of newly registered variants with increased melanization was 17–36 %. A well-expressed long-term variability in the frequencies of variants of the pronotum pattern was discovered, associated with a gradual increase in the frequency of occurrence of mass variants 1–3. Synchronously in both localities, a sharp increase up to 18–20 % was recorded in the frequency of variant 9 in 1998. Overall, synchronous samples were more similar to each other than to samples from the same localities in other years. The synchronous temporal dynamics of variant color frequencies may prove that these settlements belong to one large population of the Colorado potato beetle. In general, the obtained results indicate the ongoing processes of population structure formation of the species in the new distribution area, specifically in the territory of the Middle Urals.