Dominance of tree species of pest insects in forest biocenosis

. This article studied to determine the damage to ornamental and fruit trees caused by Yponomeuta malinellus


Introduction
It is known that 30.8% of the earth's surface is covered with forests, and the total area is 38 million km 2 . Of these, 364 million hectares or 7% are man-made [1]. Under the influence of anthropogenic factors, there was a decrease in the area of forests by 178 million ha in the world by 1990-2020. Since 2010, the state of the world's forests has been monitored by the Forest Resources Assessment (FRA) organization through satellites [2,3].
In Uzbekistan, in the next three years, special attention was paid to the rapid development of this sector, and the land of the country's forest fund was increased to 12 million hectares. In particular, ikhota plantations were established on 1.2 million hectares of the dry bottom of the Aral Sea. 10,000 hectares of forestry lands were developed, 5,500 hectares of walnut plantations, and 4,000 hectares of food and medicinal plant plantations were established. For the first time, 64 biolaboratories were established in forest farms.
In terms of protection and protection of forests, during 2021, the fight against forest diseases and pests was carried out on an area of more than 100,000 hectares, including biological control on an area of 90,000 hectares [4][5][6][7]. The forest fund of the Republic of Uzbekistan is 12 million hectares or 26.7% of the country's territory, including the forested area of 3.24 million hectares.
In order to determine the types of trees found in the biocenosis of some forest areas of Uzbekistan and the types of phytophagous insects that harm them, their biological characteristics, and the factors affecting their development, observations were made in the "Bakhmal" State Forestry of Jizzakh province, which is considered one of the largest forestry farms of Uzbekistan (2017).

Materials and methods
In total, 171 insects were identified in the forest biocenosis, 48 of them belong to 6 families, 32 are parasites, 26 are predatory entomophages, and the remaining 66 are pests living in bushes and weeds. We divided all the insects found in the forest farms into groups according to their species composition ( Forestry is divided into 25 regions, the total area of which is 12,970 hectares. During the observations conducted in forestry departments, among forest trees, fir, apple, almond, chestnut, larch, poplar, willow, apricot, safora, oak, hemlock, walnut were registered. In research and observations, the level of occurrence of registered phytophages, the affected part of forest tree species where they are developing, and the stage of pest damage to forest trees were determined. 19 different types of pests causing damage to the roots, trunk and leaves, fruits and branches of trees were identified. According to the analysis of identified phytophages, it was noted that 10 types were more common than others.

Results and discussion
According to our observations from forestry departments in areas with high humidity, it was found that leaf borers, borers, borers and root borers are encountered. Together with the insects that damage forest trees, 24 different types of entomophages were found.
It was found that such types  Note: up to 15% -rare, up to 45% -moderately common, up to 95% -common, (-) not common According to the results of systematic analysis, phytophages belong to 10 species and 7 families. According to our observations carried out in the "Oyim-2" and "Toshokhur" forest department of Andijan region state forestry (2018-2020), the dominance of Yponomeutida mallinellus L. belonging to the family of Lepidoptera, which damages apple trees, and Erschoviella musculana Ersch., which damages the fruit of walnut trees, was determined. (Table 3). Note: up to 15% -rare, up to 45% -moderately common, up to 95% -common, (-) not common Erschoviella musculana Ersch. is one of the main pests of walnuts, it reduces kernels of infected walnuts by 30% and significantly reduces marketability. Nuts infected by fruit eaters develop permanent spots on the skin of the fruit. This situation was observed a lot in forestry.
Wingspans of nut frugivorous imagos range from 17 to 22 millimeters and wingspans up to two centimeters when recorded. The front wings are dark gray and dotted with longitudinal wavy lines. The outer side of the wings has dark velvety areas with golden stripes.
It was found that females lay 70-80 eggs per season. It was observed that they lay their eggs mainly on the fruits and leaves of the walnut tree and develop for 8-10 days. The 1st generation worms that hatched from the eggs were fed with developing nut kernels for 20-25 days. It has been proven that one worm can damage several nuts during its lifetime. Infected fruits were observed to drop, and in our experiment, the drop of nuts was most observed from June 10 to July 5. During the observations, the larvae of the pest were E3S Web of Conferences 389, 03063 (2023) https://doi.org/10.1051/e3sconf/202338903063 UESF-2023 measured every 3 days and it was found that the length of the fruit-eating larvae can reach 12 to 18 mm.
Young worms feed by gnawing and filling the fruits with their waste, forming irregularly shaped lines, resulting in brown-brown spots on the affected nuts. The presence of such black spots on the fruit is considered the first sign of infestation with a fruit borer. Paranthrene tabanifonnis belonging to the Aegeridae family was found in 24.5% and Aegeria apiformis in 21.5%.

Conclusions
Studies were conducted to study the bioecology of the main pests found in Andijan forest biocenosis. Based on the results of the research, the identified insects were systematically analyzed and divided into species. In the research and observations, the occurrence level of registered phytophages, the types of forest trees where they develop, the damaged part of the trees, and the stage of development of the pest have been determined.
As a result of observations carried out in forestry departments, 19 different types of pests causing damage to the roots, trunk, leaves, fruits and branches of trees were identified. According to the analysis of identified phytophages, 10 types were found to be more common than others.
According to the results of the study of the level of distribution of representatives of the Lepidoptera family found in the forest biocenosis, the species belonging to the Yponomeutidae family in Andijan forest department: Hyponomeuta padellas L, Lithocolletis populiella L, Yponomeutida mallinellus L; belonging to the Noctuidae family: Erschoviella musculana Ersch; and, pest species such as Semasia minutana Hb, Cacoecia reticulana Hb, Pandemis heparana Schiff, and Carpocapsa pomonella L belonging to the Tortricidae family have been found. When studying the dominance of tree sections, it was noted that the dominance of apple moth and walnut fruit borer is high. The spread of tree trunk pests in the forest biocenosis, the level of occurrence was monitored. Cossus cossus L, a species belonging to the Cossidae family, was found to be 55%.