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invasion is the importation of the sawfly in its preimaginal phases with the planting material, followed by independent expansion of imagoes. the absence of broadleaved peony species in the natural ecosystems of the steppe zone is a key factor constraining the expansion of the T. talyshensis range. During mass reproduction, it causes serious damage to flower-decorative plantings.

The unique natural and climatic conditions of the region became prerequisites for agricultural science development and for formation of Abkhazia as the largest introduction place. The paper considers a working period of Sukhum Horticultural and Agricultural Experimental Station from 1894 to 2017, its structure and the main research directions. It also briefly describes the journal "Black Sea Agriculture" published at that time, the main task of which was to combine research results and observations of agricultural institutions of the Black Sea coast and individuals.

Citrus crops are the most important among subtropical crops in the Republic of Abkhazia. In 2019-2020 a new pest was discovered in the citrus agrocenosis of Abkhazia – the woolly whitefly Aleurothrixus floccosus (Maskell). The pest has been identified in all regions of the country. The degree of damage to mandarin on industrial plantations reaches 50% and more. An assessment of the resistance of 79 varieties of citrus crops from the collection of the Institute of Agriculture of the Academy of Sciences of Abkhazia to damage by a woolly whitefly (Gulrypsh district of the Republic of Abkhazia) was carried out. The degree of damage to citrus genotypes was different. It was found that the most affected varieties are Citrus limon (L.) Osbeck, as well as C. × meyeri and C. aurantifolia Sw. Tangerine, orange varieties (Hamlin, Maro and Grushevidny Koroliok) and pompelmus varieties (Mato Buntan, Natsu mican, Meteleva) are the least damaged.

Abkhazian mandarin crop is infected by over 50 pest species incurring marketable yield losses up to 83 %, which prioritises the development of new crop protection strategies that avoid organophosphorus compound usage leading to pest resistance. The studies were conducted during 2019–2020 in full-grown Citrus unshiu mandarin plantations at the Gulrypsh District of the Republic of Abkhazia adhering to the common protocol. Seven schemes were covered in study for the mandarin crop protection from rust mite Phyllocoptruta oleivora Ashmead and brown marble bug Halyomorpha halys Stål. Two schemes have been selected as optimised: scheme 5 (treatment 1 with Confidor Extra tank mix, 0.05 % WDG (imidacloprid) and 0.15 % Cytovit; treatment 2 with Vertimek tank mix, 0.1 % EC (abamectin, 18 g/L) and 0.15 % Cytovit; treatments 3--4 with Karate Zeon tank mix, 0.05 % OEC (lambda-cyhalothrin, 50 g/L) and 0.15 % Cytovit) and scheme 6 (treatment 1 with Metomax tank mix, 0.15 % SC (methomil 250 g/kg + bifenthrin 25 g/kg) and Vertimek, 0.1 % EC (abamectin, 18 g/L); treatments 2--3 with Karate Zeon, 0.05 % ISS (lambda-cyhalothrin, 50 g/L) and Vertimek, 0.1 % EC (abamectin, 18 g/L); treatment 4 with Karate Zeon, 0.05 % OEC (lambda-cyhalothrin, 50 g/L)). The schemes’ biological efficacy against mandarin pests was 80.0–84.2 and 81.3–87.7 %, providing for an average fruit weight improvement by 89.5 and 94.7 % vs. control, and 22.0 and 25.4 % vs. benchmark, respectively. Yield excess in the schemes was 85.7 and 91.7 % vs. control, and 36.8 and 41.3 % vs. economic cultivation, respectively. Class 1 fruits accounted for 63.3–65.6 % total harvest in schemes 5 and 6, whilst were not obtained in control.

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The woolly whitefly (Aleurothrixus floccosus Maskell), a species of neotropical origin, is a new pest of mandarin orange in Abkhazia. The invasive range of the species has been developing since 1959 and now covers Europe, North America, Africa, the Middle East and East Asia. It was recorded in Abkhazia in spring, 2017. The studies were conducted in 2016-2021 in all regions of Abkhazia by means of standard methods. According to the six-year study of the distribution and development of the phytophage population in the territory of Abkhazia, the species has dramatically increased in number and spread throughout all regions of the country. The identification of the pest was carried out in 2020, but the vector of its penetration into Abkhazia is yet to be clarified. Most likely, A. floccosus was introduced in Abkhazia with planting material of citrus crops. The first colonies of woolly whitefly are recorded in late May-June, followed by a rapid growth of the pest population. The development of the colony reaches its maximum by September, with a density of imago and nymphs of 102.2-152.3 units/leaf. The bioefficacy of different chemical insecticides was evaluated: organophosphorus compounds (Bi-58 Top, KE, with dimethoate as an active ingredient, consumption rate of 2 l/ha), neonicotinoids (Confidor Extra, VDG, active ingredient: imidacloprid, consumption rate of 0.4 kg/ha and Gazelle, RP, active ingredient: acetamipride, consumption rate of 0.15 and 0.5 kg/ha), chitin synthesis inhibitors (Applaud, SP, active ingredient: buprofezin, consumption rate of 0.5 and 1.0 kg/ha). Trials were set in August-September. Treatment of plants was carried out in triplicate against the background of treatment with Product 30 Plus, MME (petroleum jelly oil), the consumption rate of 30 l/ha in the third part of February. At the beginning of the trial, one leaf of mandarin, on average, had 80.2-89.4 whiteflies. From mid-August till the end of September, the number of whitefly colonies increased 1.52 times in control. The use of the insecticide Confidor Extra, WDG, 0.4 kg/ha and variants with increased rates of consumption of insecticides Apploud, SP, 1.0 kg/ha and Gazelle, RP, 0.5 kg/ha (triple treatment) appeared to be the most effective with the biological efficiency of 80.0, 86.7 and 85.8 %, respectively. Dimethoate-based organophosphorus insecticide, traditionally used in agrocenoses of citrus crops, showed insufficient effectiveness (70.0 %).

The study assessing biochemical components (sugars and organic acids) in mandarin fruits after pest control was carried out in matured plantings of cv. Unshiu mandarin in the Republic of Abkhazia in 2019-2020. The treated fruits contained a greater amount of soluble carbohydrates than the fruits in control. The predominant form of monosaccharides is fructose (17.78-17.85 g/l, with 11.89 g/l in the control) in the fruits from the standard treatment and in variant 6 (with a combination of Metamax, Vermitek and Karate Zeon), which is preferable, since it has the greatest sweetness (173 units), providing a sweeter taste of the fruit. According to the content of organic acids, variants 6 and 8 (four treatments with Diatomite, 6%) were distinguished, the content of citric acid on which was 11.86-11.3 mg/l. A more balanced taste of the fruit was in variants 6, 7 (four treatments with Diatomite, 3%) and 8 (sugar-acid index from 7.7 to 7.9 units). Taking into account the content of basic acids and sugars in mandarin fruits, it is possible to predict the impact of insecticides and their combinations on their basic taste properties.