Phenological Features of (Mamestra Brassicae L. 1758) Development in Agrocoenosis of Cabbage in the Kamin-Kashyrskyi District (Volyn Region, Ukraine)

Abstract

The animal world of Ukraine is characterized by a large variety of species. Among the lepidoptera there are a lot of pests whose larvae cause significant damage to agriculture. In the paper, we investigated the seasonal and perennial dynamics of vegetable crops pests’ population of Mamestra brassicae in the agrobiocenoses of white cabbage. The basis of our study was the investigation of the relative quantity of the pest larvae, we demonstrated the damage to plants, as well as the periods of intensive emergence of the imago and the number of generations per year. In future, this will enable the development of effective ecologically sound methods for controlling the number of species of white cabbage pests in the conditions of Kamin-Kashyrskyi district of Volyn region. Kamin-Kashyrskyi area has a flat terrain and is characterized by a warm temperate continental climate with sufficient amount of moisture, the presence of impoverished sod-podzolic soils. The area is mostly plain, with large marsh massifs, which are favorable conditions for the existence of Mamestra brassicae, as this species is moisture-loving. Observation of biocenotic connections in the agrobiocenoses of white cabbage and stationary research on the development of protection, testing and implementation systems was carried out during 2017-2018 at the garden sites of Kamin-Kashirsky district during the entire vegetation period of the plants. White cabbage is damaged throughout the period of vegetation, however, the damage that appear after emergence of seedlings and planting of seedlings into the soil are dangerous due to their consequences. In the second half of summer and in autumn, the larvae of Mamestra brassicae caused significant damage to cabbage plants in the gardens of Novi Chervyshcha. Within this area, Mamestra brassicae develops two generations per year, causing tangible damage to the agrocoenosis of cabbage of different sowing dates. The contamination of cabbage by the larva of the first and second generations approximately accounts to 24%, where 2-3 larvae live on one plant. The massive emergence of the imago occurs in the middle of May the first half of June while the average daily temperature is +20°С to +22°С. The first egg laying was recorded at the end of May, which the female lays in groups, 20-80 units on the underside of the leaves, and the embryonic development lasts 6 to 8 days. Pupae hibernate in the soil, at a depth of 8-12 cm. Significant damage to white cabbage plants was caused by the larvae of the first generation in June and early July, and of the second generation in August and early September. They intensively feed at night and at dawn, and in the daytime there is a decline in mobility and nutritional activity. Second-generation larvae often bite into cabbage heads where they make holes and pollute them with their liquid excrement, which leads to a decrease in crops. The use of microbiological drugs Dimilin and Insehar are some of the most effective ways to get rid of Lepidoptera, including larvae of Mamestra brassicae, which provide protection of cabbage plants by 93-97%.