Species Composition and Abundance of Phytophages in Agroecosystems of Major Vegetable Crops in the Right-Bank Forest-Steppe of Ukraine

Phytophagous organisms are among the major biotic factors determining the phytosanitary status of vegetable agroecosystems and may affect crop productivity. The aim of the study was to determine the species composition of the main phytophagous organisms in agroecosystems of white cabbage, tomato, eggplant, cucumber, and bulb onion under the conditions of the Right-Bank Forest-Steppe of Ukraine; to assess the abundance of soil-dwelling and aboveground phytophagous organisms and plant infestation; and to identify the characteristics of phytophage complex formation depending on the crop, its growth stage, and the year of observation. The research was conducted during 2024–2026 on experimental plots of Uman National University. Phytosanitary monitoring included route surveys, visual inspection of plants, soil sampling, and sweep-net sampling. Aboveground phytophagous organisms were assessed on 60 sample plants of each crop, while soil-dwelling phytophages were recorded by soil sampling over a total area of 2 m² per assessment. The study identified 19 species and taxa of phytophagous organisms represented by soil-dwelling and aboveground forms in the agroecosystems of the five vegetable crops. Among soil-dwelling phytophages, the highest mean abundance was recorded for Agriotes spp. larvae – 1.79 larvae/m², followed by Gryllotalpa gryllotalpa (Linnaeus) – 1.45 individuals/m² and Melolontha melolontha (Linnaeus) – 1.14 larvae/m². The greatest species diversity of aboveground phytophages was recorded in the white cabbage agroecosystem. The mean abundance of Phyllotreta spp. was 9.4 individuals/plant after transplanting and increased to 12.7 individuals/plant during leaf-ring formation. Mean plant infestation by Brevicoryne brassicae (Linnaeus) was 27.9%, whereas that by Aleyrodes proletella (Linnaeus) was 35.3%. On tomato, the mean abundance of Leptinotarsa decemlineata (Say) was 9.9 larvae/plant, that of Tetranychus urticae Koch was 3.1 mobile individuals/leaf, and that of Helicoverpa armigera (Hübner) was 1.0 larva/plant. On eggplant, the mean abundance of Leptinotarsa decemlineata (Say) was 30.6 larvae/plant, approximately 3.1 times higher than on tomato. In the cucumber agroecosystem, plant infestation by Aphis gossypii Glover averaged 15.6%, while the abundance of Tetranychus urticae Koch was 3.9 mobile individuals/leaf. On bulb onion, the abundance of Thrips tabaci Lindeman increased from 9.4 individuals/plant during active vegetative growth to 10.1 individuals/plant during bulb formation and growth. Interannual variability in phytophage population abundance was established: for most of the studied species and taxa, the highest values were recorded in 2025, followed by a decline in 2026. The obtained results can be used to improve phytophage monitoring systems and to refine the timing of plant protection measures in agroecosystems of major vegetable crops in the Right-Bank Forest-Steppe of Ukraine.