ANALYSIS of the Distribution of the Western Corn Rootworm (Diabrotica Virgifera Virgifera le Conte) in Agrocenoses of Cherkasy Region and Determination of Resistance of Individual Maize Hybrids to Damage

Abstract

Introduction.The expansion of the western corn beetle (Diabrotica virgifera virgifera Le Conte) in Ukraine in recent years has complicated the quarantine situation. In the area where the pest is widespread, significant losses of corn were found, especially when it is grown in monoculture. To reduce the number of pests and reduce its harmfulness, it is enough to follow the rotation of crops: the return of corn to the field in three or four years.But growing corn in a two-field crop rotation leads to rapid adaptation of the pest. Attempts by genetic engineering to obtain transgenic maize lines resistant to diabrotica have not yet yielded the expected results. Genetically modified plants are effective only for regulating the number of adults. The main prerequisite of any plant protection system is modern phytosanitary monitoring and forecast of the Серія «Біологічні науки», 202136spread of the western corn beetle, which should be a system of collection, accumulation, analysis and use of phytosanitary, in particular, quarantine information.Purpose.Of the work is to analyze the distribution of phytophagous in the conditions of Cherkasy region and protection of the resistance of maize hybrids that have passed the state variety test to western corn rootworm.Methods.Field, accounting, laboratory and static methods were used in the research.Results.The analysis of the areas inhabited by the western corn beetle of the Cherkasy region in 2019 shows,that only in seven districts of the region outbreaks of western corn beetle infection were detected, however, the natural and climatic conditions of our region are favorable for the spread of this dangerous quarantine pest, which necessitates constant monitoring of outbreaks. During the three-year period of our observations, the phytophagous inhabited fields adjacent to river floodplains and lowlands. The development of the western corn beetle is closely related to the temperature conditions of Cherkasy region.During our research it was established that the beginning of flight of beetles occurred at the sum of effective temperatures (∑ t) above 15 ºС in the range of 750-850 ºС. The stages of passage of separate phases of ontogenesis of the western corn beetle in the territory of Cherkasy region according to temperature indicators allow us to effectively plan pest monitoring and quarantine extermination measures. Laboratory evaluation of 25 maize hybrids for resistance to the western maize beetle. Of all the studied maize hybrids, 1 hybrid was highly resistant, 3 hybrids were resistant.Originality. The territory of Cherkasy region is analyzed regarding the distribution of the western corn rootworm. 25 maize hybrids of different maturation periods were evaluated for resistance to the western maize beetle, 8 hybrids were selected for practical use on the basis of high level of stability and the highest yield.Conclusions. Thus, the Analysis of the territories of Cherkasy region in 2018-2020 on the distribution of western corn beetle (Diabroticavirgifera virgifera Le Conte) shows that the pest was found in 7 districts: Zvenigorod, Korsun-Shevchenko, Monastyryshche, Talniv, Uman, KhShpolyansky. The most resistant to damage by the western corn beetle are early-maturing hybrids of corn (FAO 100-199) –Dolphin, DKS 3476, ДМС 1915.Late hybrids (FAO 500-600) are unstable –DM Native, Kharkiv 43 M (Donor M), Kharkiv 45 M (Industry M), Lyubava MV, Standard. It was determined the lowest damage to plant seedlings by the western corn rootworm in the early stages of sowing corn –5% in the hybrid Sensor. The most damaged plants at late sowing stages. Varieties LCA 4010 and DM Sunrise were damaged by 22,8% and 21,7% respectively.Key words:FAO maize hybrids (100-200); crop rotation; phytosanitary monitoring, the number of pests.