Woolly whitefly in agrocenoses of citrus crops of Abkhazia and the eff ectiveness of chemical plant protection products

Abstract

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 %).