Pests of oil producing cabbage crops in the eastern forest-steppe of Ukraine

1V.V. Dokuchaiev Kharkov National Agrarian University, v. Dokuchaevske, Kharkiv region, 62483, Ukraine Altai State University, Barnaul, Russian Federation National University of Life and Environmental Sciences of Ukraine, Kyiv, 03041, Ukraine Zhytomyr National Agroecological University, Zhytomyr, 10008, Ukraine Zhytomyr Agricultural College, Zhytomyr, 10031, Ukraine *Corresponding author E-mail: sergejstankevich1986@gmail.com Received: 20.09.2020. Accepted 26.10.2020


Introduction
The identification of conditions that contribute to the reproduction of the harmful insects in one place or another in many cases makes it possible to scientifically substantiate and implement the measures in order to limit their harmful activity and even completely eliminate the danger. It is well known that the insects, both geographically and locally, are extremely unevenly distributed. This unevenness is caused by the differences in the natural and economic conditions of the particular regions, the Ukrainian Journal of Ecology, 10(5), 2020 differences on which both the possibility of existence and the intensity of the insect reproduction depend. Such biotic factor as the vegetation distribution, which is the forage base for most insects, influences their spreading greatly. This connection is strongly expressed among the harmful herbivorous insects (Dobrovolskyi, 1959). To a greater extent this connection is inherent in the insects feeding on a single kind of food or monophagous pests as well as in the insects feeding on a limited variety of food or oligophagous pests (Kozhanchikov, 1955). The presence and distribution of the plants which are cultivated or used by humans and on which the insects are fed is certainly the first and basic condition for the emergence of a zone or a breeding ground of harmfulness. The presence of the most preferred by the insects fodder plants often leads to the formation of a zone or a centre of the greatest damage (in the presence of other favourable conditions for the existence and reproduction of the pest) (Dobrovolskyi, 1959). The monophagous pests that feed and reproduce on the crops which occupy a restricted area have the most sharply restricted zones or the breeding grounds with the greatest harmfulness. At the same time the ecological connections which are based on a high degree of physiological and ecological adaptation to the feeding on the certain plants and to the conditions of growth and agricultural techniques of cultivation of the insect nourishing crops are revealed (Kozhanchikov, 1955). In the first turn the human economic activity leads to the change of the natural vegetation cover and replacement it by a few new species of plants and this fact is extremely strongly reflected in the quantitative and qualitative indices of the entomofauna (Buch, 1998, Wachowiak, 1999. The pure crops in nature do not occupy the large areas, but they can occupy 100 or more hectares in the agroceonoses and much more heavily populated by the pests (Tachvanainen, Root, 1972). As B.V. Dobrovolskyi (Dobrovolskyi, 1959) notes the first and the main condition for the emergence of the harmful zones of any kind of insects is the presence and distribution of their fodder crops (in the presence of other favourable conditions for their reproduction and spreading). Under natural conditions the insects feed on the wild growing plant species and weeds; this fact greatly regulates their number. Therefore the anthropic factor begins to play a significant role. In the first turn the human economic activity leads to the change of the natural vegetation cover and replacement it by a few new species of plants which is extremely strongly reflected in the quantitative and qualitative indices of the entomofauna. New relationships are formed between the species; the trophic chains are restructured and the adaptations to exist in a changed environment are arisen. Certain species of the pests also become dominant under favourable weather and biological conditions (Buch, 1998, Wachowiak, 1999. A striking example of this is the pests of the cabbage crops. According to the data of M.M. Bogdanov-Katkov (Bogdanov-Katkov, 1920) the pests of the cabbage crops under natural conditions feed on the following plants: field shepherd's purse (Capsella bursa-pastoris Moench.), field pennycress (Thlaspi arvense L.), yellow rocket (Barbarea vulgaris R. Br.), field pepper weed (Cardaria campestre R. Br.), pepper grass (Cardaria draba L.), camelina (Camelina dentata Pers.), wild radish (Raphanus rapanistrum L.) and others. Timely destruction of these weeds in all crop rotation fields limits the development of the pests.
The number of weeds in the natural biocoenosis is not significant and therefore the cultivated plants from the Brassicaceae family play the decisive trophic role for the insects; the acreage under these crops is constantly increasing. Their species and variety composition is very diverse. In 2018 according to the State Register of Plants Varieties Suitable for Distribution in Ukraine the following number of the cabbage crops varieties is indicated: white cabbage -242 varieties, cauliflower -77 varieties, red cabbage -33 varieties, Pe-tsai cabbage -27 varieties, broccoli cabbage -22 varieties, Savoy cabbage -10 varieties, turniprooted cabbage -9 varieties, Brussels sprouts -6 varieties, small radish -76 varieties, garden radish -10 varieties, perennial wall-rocket -3 varieties, turnips -2 varieties, green mustard -2 varieties, field mustard -2 varieties, rocket salad -1 variety, black radish -1 variety, field turnip -1 variety, winter rape -257 varieties and 114 parent components, spring rape -54 varieties and 16 parent components, spring leaf mustard -11 varieties, white mustard -10 varieties, spring false flax -9 varieties, oily radish -5 varieties, winter leaf mustard -7 varieties, field mustard -3 varieties, annual turnip rape -2 varieties, black mustard -2 varieties, green mustard -2 varieties and colza -1 variety.
Today the main oil producing crops from the Brassicaceae family in the world and in Ukraine are winter rape (Brassica napus оleiferа bienis D. C.) and spring rape (Brassica napus oleіfera annua Metzg.). Currently the acreage of these crops in the world is over 40 million hectares, and in Ukraine there are more than 1 million hectares. Less common crops are white mustard is not grown in our country at all. In addition the new fodder crops from the Brassicaceae family such as perko and cow cabbage that are new for our country, are being tested at the research stations. Such amount of high quality fodder crops contributes to the migration of the insects from their natural habitats to the agricultural land. The insect habitat begins to expand and coincides with the areas of the cultivated plants growing. To obtain the high and sustainable yields of all agricultural crops is impossible without protection of the plants from the harmful insects. The loss of the crops due to pests is huge, especially during their reproduction on a mass scale. The entomological community of agriculture system of the oil producing cabbage crops is extremely rich and contains several hundred species. As a result of their vital functions more than 50% of the crops can be lost and as far as 25-55% growth increase in the yield can be reached due to the pollinating insects (Prushynsky, 1995). Despite the short-term existence of the agriculture system of the spring oil producing cabbage crops (90-120 days) their entomofauna is characterised by a considerable diversity of the species composition (Zhuravskyi, 2008). According to V.P. Fedorenko (Fedorenko, 2008) in recent years the number of pests in the spring and winter rape agriculture system has been increasing rapidly in Ukraine.

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Pests of oil producing cabbage crops Ukrainian Journal of Ecology, 10(5), 2020 In the countries of the former USSR the cabbage pest complex is characterised by the large species diversity (more than 300 species) (Kostromitin, 1980). Maksymov M.P. (Maksymov, 1990) names 80 species of insects that damage the oil producing cabbage crops in Ukraine. According to O.A. Ivantsova (Ivantsova, 2010) 103 species of pests were registered on the brown mustard in the Volga region. Velychko V.V. (Velychko, 1951) indicates that about 86 species of insects damage the crops of mustard in the Non-Black Zone of the Russian Federation. In Uzbekistan (Burda, 1970) 82 insect species damage the cabbage crops. Minkevych O.I. (Minkevych, 1949) names 61 species of insects that damage the mustard crops in Russia. According to the data of L.O. Kanter (Kanter, 1980) 45 species of the harmful insects of cabbage crops were recorded in Western Trans-Baikal. In Latvia about 50 insect species damage the cabbage crops (Cinitis, 1972). Lhagwa Zh. (Lhagwa, 1971) lists 25 insect species that cause damage to the cabbage crops in Mongolia. According to various data from 34 (Ovchinnikova, 1971(Ovchinnikova, , 1972 to 40 (Gortlevskii, 1983) species of insects (Gortlevskii, 1983) damage the cabbage crops in the Moscow region. G.A. Moskaliova (Moskaliova, 1985) names about 30 species of pests in the Leningrad region. Antsupova T.Ye. (Antsupova, 1984) names 19 species of pests in the Kuban. Amosov Yu.M. (Amosov, 1980) describes 25 species that damage the cabbage crops in Yakutia. Semakov V.V. (Semakov, 1966) names 22 species of harmful insects in Kamchatka. Osipov V.G. (Osipov, 1986) notes that 19 species of pests are harmful to the cabbage crops in Belarus. The most complete faunistic description of the cabbage crops pests under the conditions of Forest-Steppe and Polissia of Ukraine is given in the monographic work of A.P. Kryshtal (Kryshtal, 19590. He described 211 species of the insects that damage these crops that constitute 14% of all insect pests; among them 56 species are specialized. Such scientists as M.P. Sekun (Sekun, 2009), M. Krut (Krut, 2011), and L.P. Kava (Kava, 2013) indicate that about 50 species of the pests damage the spring and winter rape crops in Ukraine. V.P. Vasiliev (Vasiliev, 1989) and Yu. H. Krasylovets name 47 specialised insect species that damage the rape crops in Ukraine. Z.I. Hurova (Hyrova, 1963) and L.I. Kolesnik (Kolesnik, 2007) name 40 species, and V.S. Zhuravskyi (Zhuravskyi, 2007) lists 27 species of the insect that are harmful for the rape crops. According to R.V. Yakovliev (Yakovliev, 2008(Yakovliev, , 2010(Yakovliev, , 2012) 32 species of phytophagous pests damage the mustard crops in the Forest-Steppe of Ukraine. Laba Yu. R. (Laba, 2009, 2012 indicates that 46 harmful insect species damage the spring and winter rape crops in the Central Forest-Steppe of Ukraine. In the Forest-Steppe of Ukraine the most harmful species are the cruciferous fleas (Phyllotreta spp.), rape blossom beetle (Meligethes aeneus F.), cruciferous bugs (Eurydema spp.), seed-eating ceuttorrhync beetle ((Ceuthorrhynchus quadridens Panz.), turnip fly (Athalia rosae L.) and cabbage aphids (Brevicoryne brassicae L.) (Yakovliev, 2008;).
Gordieieva O.F. (Gordieieva, 2003) indicates that under the conditions of the left-bank Forest Steppe of Ukraine 42 species of the phytophagous pests belonging to 8 lines and 19 families were found on the rape crops. The most dangerous species are the cruciferous fleas, rape blossom beetle and cabbage aphid. According to I. Tarushkin (Tarushkin, 2006) the most dangerous pests of the rape crops in the territory of Ukraine are the rape blossom beetle, seed-eating ceutorrhynchus beetle, turnip fly, and the brassica pod midge. In Belgium, Bulgaria, Germany, Slovakia and France the most harmful species of the rape crops pests are the cruciferous fleas, ceutorrhynchus, rape blossom beetle, turnip fly, brassica pod midge and cabbage aphids (Hoffman, 1983, Knoll, 1997, Volker, 2003. The main pests of the rape crops in Switzerland (Carrel, 1995) are the rape blossom beetle, ceutorrhynchus and the cruciferous fleas. In Hungary the most harmful species of the oil producing cabbage crops are the rape blossom beetle and ceutorrhynchus (Marczali, 2006). In Poland the greatest losses to the winter rape crops are caused by the rape blossom beetle, ceutorrhynchus and the pod midge (Mrowczynski, 1992(Mrowczynski, , 2003(Mrowczynski, , 2007. Recently the diamond black moth and the cabbage aphid (Mrowczynski, 2006(Mrowczynski, , 2007 deserve the special attention. The rape blossom beetle, pod midge, cruciferous fleas, cabbage root fly and turnip fly cause the greatest damage to the spring rape crops in Poland (Vilinskiy, 1974;Walkowski, 2002). Shpaar D. (Shpaar, 2007) points out that the rape blossom beetle is the most dangerous pest of the cabbage crops in Germany, Poland and France. In Norway one of the main pests of the oil producing cabbage crops is the rape blossom beetle (Andersen, 2008). M. Krut notes that different species of pests cause unequal harm in the different regions of Ukrain. (Krut, 2003). In such oblasts as the Kyivska, Sumska, Vinnytska, Khmelnytska, Cherkaska, Chernivetska, Ivano-Frankivska, Chernihivska, Odeska and Khersonska the complex of the cruciferous fleas is the most dangerous one. In the Kyivska, Sumska, Vinnytska, Chernivetska, Ivano-Frankivska, Chernihivska and Lvivska oblasts the most dangerous pest is the rape blossom beetle. The turnip fly causes damage in the Kyivska, Sumska, Khmelnytska, Chernivetska, Cherkaska, Vinnytska, Kharkivska, Rivnenska and Khersonska oblasts. The seed-eating ceutorrhynchus beetle is especially dangerous in the Kyivska, Sumska, Volynska, Lvivska, Rivnenska and Ivano-Frankivska oblasts. Tsybulko V.I. (Tsybulko, 1975) notes that in the Eastern Forest-Steppe of Ukraine the cabbage crops are damaged by about 60 species of multi-faceted and specialized insects. The aim of our research was therefore to analyze the pest species of oil producing cabbage crops in the eastern forest-steppe of Ukraine.

Materials and methods
In 2007-2019 the species composition of the oil producing cabbage crops pests was investigated throughout the whole vegetation period by mowing with the entomological catching net, using the soil traps, the Petliuk box and hand collection. The number of pests was recorded according to the generally accepted methods (Omeliuta 1986; Stankevych, Zabrodina, 2016). The researches were carried out on the crops of the oil producing cabbage plants in the fields of the Educational, Research and Production Centre "Experimental Field" of Kharkiv National Agrarian University named after V.V. Dokuchaiev and the state enterprise "Research Farm "Elitne" of the Institute of Plant Growing named after V.Ya. Yuryiev of the National Academy of Agrarian Sciences of Ukraine. The collected entomological material was analysed and systematised; and the species composition of the insects was determined at the Zoology and Entomology Department named after B.M. Lytvynov of Kharkiv

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Pests of oil producing cabbage crops Ukrainian Journal of Ecology, 10(5), 2020 National Agrarian University named after V.V. Dokuchaiev. The accuracy of the identification of certain harmful species of insects was confirmed by PhD in Biology V.M. Hramma, the head of the Laboratory of Insect Ecology of Kharkiv National Agrarian University named after V.V. Dokuchaiev.

Results and discussion
During the vegetation periods of 2007-2019 in the fields of the Educational, Research and Production Centre "Experimental Field" of Kharkiv National Agrarian University named after V.V. Dokuchaiev and the state enterprise "Research Farm "Elitne" of the Institute of Plant Growing named after V.Ya. Yuryiev of the National Academy of Agrarian Sciences of Ukraine we have identified 54 species of specialised and multi-faceted pests of the oil producing cabbage crops belonging to 8 lines and 22 families (Tables 1, 2). Among them 29 species are specialised pests and 25 species are multi-faceted ones (Figure 1) (Yevtushenko, Stankevych, Vilna, 2014;Stankevych, 2015;Yevtushenko, Vilna, Stankevych, 2017;Stankevych, 2018).
The frequency of the pest species occurrence on the rape and mustard crops (Table 1) is the following: species that populate the crops on a mass scale -8 (14,8%), the moderately spread species -6 (11,1%), species that have the insignificant population density -40 (74,1%). The cabbage bug, mustard bug, cabbage aphid, rose chafer, rape blossom beetle, mesographe flea beetle, flea beetle and diamond black moth belong to the species that populate the crops on a mass scale. Among them 4 species belong to the Coleoptera line, 2 species belong to the Hemiptera line, 1 species belong to the Homoptera line and 1 species belong to the Lepidoptera line. The representatives of the Coleoptera line are the dominant species; their part in the entomocomplex structure is 48% (26 species, see Table 2). The economic importance of these pests is not the same and greatly depends on the population density, phenophase of the crop (Table 3) as well as on weather conditions. For example hot and dry weather is favourable for the cruciferous fleas when the plants are more weakened and the fleas are more voracious. The cabbage aphids like warm weather.
In the phase of sprouting (up to 4 true leaves) the complex of the cruciferous fleas, tenebrionid beetle and earth-boring dung beetle are the most dangerous pests. The latter can be found along the perimeter of the field. In the phase of the rosette formation the cruciferous bugs (Figure 3), other multi-faceted species of bugs, cabbage aphids, cruciferous fleas (Figure 4), leaf beetles, the caterpillars of butterflies and moths (Figure 7) as well as the larvae of turnip fly cause the greatest damage to the crops. The ceutorrhynchus, barids and Lixus ascanii L. are especially dangerous during the period of the stalk formation In the phase of budding the rape blossom beetle and cabbage aphid cause the considerable damage. During the stage of plant flowering the especial damage is caused by the rape blossom beetle ( Figure 5), chafers ( Figure 6) and cabbage aphid (Figure 2).
The cabbage seed-pod beetle, Brassica pod midge, cruciferous bugs and cabbage aphid are especially dangerous in the phases of the pod formation and ripening. The oil producing cabbage crops have 2 critical periods, they are the phenophases of sprouting and flowering. The complex of the cruciferous fleas and rape blossom beetle are especially dangerous in these phenophases. This thesis is devoted to studying the biological and ecological peculiarities of the pests, their harmfulness as well as the effective ways in order to protect the spring rape and mustard crops from the harmful insects.

Conclusions
A total of 54 species of harmful insects were found on the oil producing cabbage crops which belong to 8 lines and 22 families. Among them 29 species are the specialised pests and 25 species are multi-faceted ones. Among them, eight species belong to those that populate the crops on a mass scale, 4 species of which belong to the Coleoptera line. In the phase of sprouting (up to four true leaves) the complex of cruciferous fleas, tenebrionid beetle and earth-boring dung beetle are the most dangerous pests. The latter can be found along the perimeter of the field. In the phase of the rosette formation the greatest damage to the crops is caused by the cruciferous bugs, other multi-faceted species of bugs, cabbage aphids, cruciferous fleas, leaf beetles, the caterpillars of butterflies and moths as well as the larvae of the turnip fly.The ceutorrhynchus, barids and Lixus ascanii L. are especially dangerous during the period of the stalk formation. In the phase of budding the rape blossom beetle and cabbage aphid cause the considerable damage. During the stage of plant florescence the especial damage is caused by the rape blossom beetle, chafers and cabbage aphid. The cabbage seed-pod beetle, Brassica pod midge, cruciferous bugs and cabbage aphid are especially dangerous in the phases of the pod formation and ripening.