Dispersal and development of beet webworm Loxostege sticticalis (L.) in Ukraine

Abstract

migratory and outbreak capacities. Its taxonomy at the generic level has been changed several times, the two most acknowledged genera being Loxostege and Pyrausta. The beet webworm Loxostege sticticalis (L.), (Pyraloidea, Crambidae) is a dangerous outbreak pest, causing serious damage to the crops such as soybean, sugar beet, alfalfa and sunflower in Eurasia, including Northern China and steppe zones of European and Asian parts of Russia (Chen et al. 2008, Frolov et al. 2008). It was initially described as Pyralis sticticalis (Linnaeus 1761), later it was attributed by the different authors to the genera of Botys Latreille, 1802, Loxostege Hübner, 1825, Margaritia Stephens, 1827 and Phlyctaenodes Hampson, 1899. The combination Loxostege sticticalis is the one most widely accepted by the modern taxonomic summaries (de Jong 2011, Goater et al. 2005, Heppner 1998, Karsholt and Razowski 1996). Material and Methods: The field data was obtained in 2017 – 2018 at the research field in different regions of Ukraine. Adult moths of beet webworm Loxostege sticticalis (L.) were caught by net at the meadows in Luhansk, Zaporizhia, Mykolaiv, Kherson regions. Commonly accepted methods of faunal studies in entomology and calculation of insect numbers, field and laboratory studies, modeling the population dynamics of insects were used in the research. The analysis of Department of Forecasting reports, Phytosanitary Diagnostics and Risk Analysis of Ukraine were conducted. Results: In 2018, the first spring generation had the most favorable conditions for development - enough moisture, moderate temperatures, presence of flowering vegetation, which led to a significant increase in the number of depredators, especially in the centers of the southeastern and sometimes central areas. The beet webworm Loxostege sticticalis (L.) developed within three generation in most areas in the spreading zones, except Kharkiv, Poltava and Vinnytsia regions, where only two generations were noted. Conclusion: Considering the degree of the beet webworm Loxostege sticticalis (L.) threat, it is necessary to observe the dynamics of their dispersal constantly, which would allow to avoid “unexpected” destruction of agricultural crops by caterpillars. In 2019 it is necessary to strengthen the beet webworm Loxostege sticticalis (L.) appearing, to monitor the depredator’s development and to use pesticides in time.