1. Introduction

Insect pests constitute a significant components of forest ecosystems yet their contributions in global environmental change and forestry dynamics has often been overlooked. Despite the mountainous nature of Central Asia, forests cover a relatively small proportion of each country. The forested areas are predominatly composed of Saxaul (Haloxylon spp.), Ulmus, Salix, Populus and other shrubs, especially within the desert and semi-desert landscapes of the region. Willow is a tree belonging to the genus Salix of the Salicaceae family. Two species of it, Salix songarica and Salix wilhelmsiana, are found in the conditions of the South Aral Sea [12,13].

The insects of the two neighboring regions of region Khorezm and republic of Karakalpakstan in the Aral Sea Basin are listed and described based on literature data. These regions consist of irrigated farmland, forest-tugay and deserts of Kyzylkum and Karakum. They exhibit a series of different ecosystem types, and reference is made to the corresponding entomocomplexes [15]. Phytophagous insects or herbivorous, are significant pests in Salix and Ulmus forestry. By feeding on plant sap, they cause direct damage to their host plants, leading to discoloration, deformation of leaves and shoots, or the formation of galls and pseudo galls. Pest adults can be dislodged from branches by beating foliage. In spring, evidence of infestation includes sap flow down the trunk and the presence of moist sawdust pushed out of galleries. Adults are often observed walking on trunks or branches, particularly at night. Additional signs of infestation include wilting suckers and pronounced holes in the young stems caused by adults feeding [2,5,6]. Currently, information on impact of pests and diseases affecting forests in Uzbekistan is incomplete. Among the pest, the order Heteroptera or true bugs are a large group with more than 40,000 species in approximately 50 families distributed across the world [11,26]. In Russia, 760 species in 285 genera, and 35 families, are recorded [25], however, more than 1250 species are distributed in Central Asia [7], and 700 species of true bugs are distributed in Uzbekistan [4]. An annotated list of the registered species of pests insects of Salix of the described region is provided. Furthermore, an updated checklist of pest insects affecting Salix in the South Aral Sea areas is presented based, on literature records with the latest taxonomic and nomenclatural changes.

2. Material and Methods

Study area

The Republic of Uzbekistan is located between the Amudarya and Syrdarya Rivers, and its total area is 448,900 km². The territory of the republic is 1,425 km from east to west and 930 km from north to south [16,20]. The Northeast biogeographic regional part of Uzbekistan is situated between the western part of the Tien Shan Mountains and the Syrdarya River [3,21].

Uzbekistan’s geographical position at the crossroads of several Central Asian bio-geographical regions underpins the remarable richness of its flora and fauna. This biodiversity reflects the variety of natural conditions across the country, where vast plains occupied by various desert types, mountain steppes, forests, alpine meadows, tugai thickets, and water bodies form distinctive ecosystems [9,10]. Tugai and floodplain ecosystems persist in limited areas along the Amudarya River. Meanwhile, the degraded low mountains and escarpments of Ustyurt Plateau located amidst the desert provide refuge for many rare species. However, at the same time, they are subject to pressure from animal husbandry as well as from the mining industry (building stone, gypsum raw material, etc.). Forest-tugai ecosystems play a vital role in both the economy and environmental protection efforts [19,24].

A peculiarity of most natural ecosystems is their heightened vulnerability, associated with climate aridity. As a resut, the resistance of the ecosystems to external forces is rather low and any anthropogenic interference acts as an additional factor contributing of the degradation of natural systems. The geographical scope of this checklist covers the South Aral Sea areas (Fig. 1).

Figure 1. Biogeographic region South Aral Sea areas in Uzbekistan

The studies conducted in Uzbekistan from 1995 to 2024 by many researchers on pests of Salix are examined in detail with information about each species sourced from the literature. The Latin names of pest insects taxa and classification follow Favret (2023) [8]. The names of specific subgenera and taxa of lower rank within genera are arranged in alphabetical order. Under each pest insect species and subspecies, the first publication from Uzbekistan is cited. All species studied and identified for the fauna of South Aral Sea areas are verified by Global Biodiversity Information Facility (GBIF). This is systematic checklist covers pests of Salix plants.

Pest description and damage. There are several species of pests known to feed on the foliage, stems, flowers, or bark of Salix. Insect material was collected using sweeping nets and glass containers, or by tube aspirators (Fig. 2).

Figure 2. Equipment used for collecting insects. Nets, aspirator, light trap

The research was conducted using standard entomological methods. Night species were collected with a special trap on plants, roadsides, tree trunks and leaves. The samples killed in the killing bottles are then placed in petri dishes with blotter paper and information slips indicating when, where and from which plant they were collected. Insects were killed in glass tubes with ethyl-acetate or were directly stored in 70% ethyl-alcohol [18].

3. Results

To date, 35 species and subspecies of Salix plant pests have been identified in the South Aral Sea region, based on data from research scientists and our own research. These included 6 species of Hemiptera, 13 species of Coleoptera, 1 species of Diptera, and 15 species of Lepidoptera.

Order: Coleoptera Linnaeus, 1758

Family: Apionidae Schönherr, 1823

Genus: Apion Herbst, 1797

Apion sp.

Family Buprestidae Leach, 1815

Genus: Agrilus Curtis, 1825

Agrilus uzbekistanus Stepanov, 1958

Genus: Trachypteris Kirby, 1837

Trachypteris picta (Pallas, 1773)

Family Cerambycidae Latreille, 1802

Genus: Aeolesthes Gahan, 1890

Aeolesthes sarta Solsky, 1871.

Genus: Xylotrechus Chevrolat, 1860

Xylotrechus namanganensis Arkhangel’skii, 1941

Family Chrysomelidae Latreille, 1802

Genus: Altica Geoffroy, 1762

Altica deserticola (Weise, 1889)

Genus: Chrysomela Linnaeus, 1758

Melosoma populi Linnaeus, 1758

Genus: Clytra Laicharting, 1781

Clytra guadripunctata (Linnaeus, 1758)

Genus: Cryptocephalus Geoffroy, 1762

Cryptocephalus melanoxanthus Lopatin, 1952.

Cryptocephalus bipunctatus (Linnaeus, 1758)

Genus: Plagiodera Chevrolat in Deiean, 1836

Plagiodera versicolora Laicharting, 1871

Family Curculionidae Latreille, 1802

Genus: Chlorophanus Schönherr in Sahlberg, 1823

Chlorophanus caudatus Fåhraeus, 1840

Genus: Platymycterus Marshall, 1918

Platymycterus trapezicollis (Ballion, 1878)

Order: Diptera Linnaeus, 1758

Family: Agromyzidae Fallen, 1823

Genus: Melanogromyza Hendel, 1920

Melanagromyza schlingeri Sasakawa, 1992

Order: Hemiptera Linnaeus, 1758

Family: Aphididae Latreille, 1802

Genus: Chaitophorus Koch, 1854

Chaitophorus salicti (Schrank, 1801)

Chaitophorus salijaponicus niger (Mordvilko, 1929)

Family: Diaspididae Maskell, 1878

Genus: Chionaspis Signoret, 1869

Chionaspis polypora Borchsenius, 1949

Family: Eriococcidae Brues 1932

Genus: Gossyparia Signoret, 1875

Gossyparia salicicola Borchsenius, 1949

Family: Pentatomidae Leach, 1815

Genus: Apodiphus Spinola, 1837

Apodiphus integriceps Horvath, 1888

Family: Tingidae Laporte, 1832

Genus: Monosteira A. Costa, 1862

Monosteira discoidalis (Jakovlev, 1883)

Order: Lepidoptera Linnaeus, 1758

Family: Cossidae Leach, 1815

Genus: Cossus (Fabricius, 1793)

Cossus cossus (Linnaeus, 1758)

Family: Erebidae Leach, 1815

Genus: Catocala (Schrank, 1802)

Catocala elocata (Esper, 1787)

Catocala lupina (Herrich-Schaffer, 1851)

Catocala neonympha (Esper, 1805)

Catocala nupta (Linnaeus, 1767)

Catocala optima Staudinger, 1888

Catocala puerpera (Giorna, 1791)

Genus: Lymantria (Hubner, 1819)

Lymantria dispar (Linnaeus, 1758)

Family: Geometridae Leach, 1815

Genus: Cabera (Treitschke, 1825)

Cabera pusaria (Linnaeus, 1758)

Genus: Campaea (Lamarck, 1816)

Campaea margaritaria (Linnaeus, 1761)

Family: Noctuidae Latreille, 1809

Genus: Acronicta (Ochsenheimer, 1816)

Acronicta psi (Linnaeus, 1758)

Family: Nolidae Bruand, 1847

Genus: Earias (Hubner, 1825

Earias clorana (Linnaeus, 1761)

Family: Nymphalidae Rafinesque, 1815

Genus: Nymphalis (Kluk, 1780)

Nymphalis polychloros (Linnaeus, 1758)

Family: Psychidae Boisduval, 1828

Genus: Ptilocephala Rambur, 1866

Ptilocephala plumifera (Ochsenheimer, 1810)

Family: Sphingidae Latreille, 1802

Genus: Laothoe (Fabricius, 1807)

Laothoe populi (Linnaeus, 1758)

Total 35 species

4. Discussion

There are very few studies have been conducted on Salix pests in Uzbekistan. Prior to this study, there was no comprehensive checklist of pests Salix in Uzbekistan before this study. In contrast, there are several checklists for other insect groups in this country particularly in recent years [1,14,15,17]. Due to the unique ecosystem, biodiversity and high level of endemism of vascular plants in South Aral Sea forest ecosystem (Uzbekistan) there is a high probability of finding additional new record species and even new species to science. Despite this, the pests fauna of Uzbekistan has not been well investigated yet, considering the country’s high floral and landscape diversity of this country. About 60% of the pests species spend all or part of their life feeding on trees.

According to our research, out of the 35 pest species identified on Salix plants, 22 species (63%) were found to damage the stems, while 13 species (37%) were recorded to damage the leaves. Additionally, when studying the relationship of insects with the plants, they were classified into dominant species, incidental species, secondary species, and tertiary species. Four insect species (Gossyparia salicicola, Chionaspis polypora, Chaitophorus salicti, and Chaitophorus salijaponicus niger) were classified as incidental species. One insect species (Apodiphus integriceps) belonged to the secondary species category, one species (Plagiodera versicolora) to the tertiary species category, while the remaining 29 insect species were identified as dominant species (Table 1).

Table 1. The species composition and damage caused by willow (Salix) pests under the conditions of Karakalpakstan

An analysis of pest species found on Salix plants in the Southern Aral Sea region revealed that 12 phytophagous species matched the information reported in the literature [22,23]. Thus, the 35 pest insect species identified were recorded as belonging to 4 orders, 19 families, and 28 genera (Figure 3).

Figure 3. The ratio of pest orders of willow (Salix) under the conditions of Karakalpakstan

ACKNOWLEDGMENTS

We are grateful to the Committee on Ecology and Environmental Protection of the Karakalpakstan (Republic of Uzbekistan) for its close cooperation. In addition to the deceased professor A.Sh. Khamraev and to the team of Khorezm academy of Mamun, Academy of Sciences of the Republic of Uzbekistan and Karakalpakstan Institute of Agriculture and Agrotechnologies for granting permission to use insects species collections.

CONFLICT OF INTERESTS

The authors declare that there is no conflict of interest regarding the publication of this paper.