Size-Dependent Selective Leaf Damage by Insects and Some Methodological Implications of This Phenomenon

The area of leaves on birch (Betula pubescens ssp. tortuosa) auxiblasts and brachyblasts and the degree of their damage by the complex of leaf-gnawing and leaf-mining insects were studied in a light birch forest. The results showed that phyllophagous insects, primarily snout beetles, prefer young leaves on the apexes of auxiblasts. Thus, selective damage is inflicted on smaller leaves, both on the auxiblasts and in the entire sample. This phenomenon is widespread and may manifest itself in different ways, depending on the pattern of leaf area distribution along the extended shoot and the feeding preferences of the insects. Thus, it is necessary to reconsider research methods and approaches based on the assumption that insects damage leaves nonselectively, irrespective of their size.     

Correlated northward distribution of macrolepidopterans and their food plants along the Ural Mountains

Lists of macrolepidopterans inhabiting the Southern, Middle, and Polar Urals have been used for analyzing the relationship between the species richness of these insects with that of the families of plants on which their larvae feed. The results have shown that this factor in the Southern Urals accounts for approximately 75% and 65% of variation in the species richness of lepidopterans on woody and herbaceous plants, respectively. In the Polar Urals, this correlation is markedly weaker. Latitudinal trends in trophic preferences of individual lepidopteran taxa have been revealed. Probable causes of changes in the relative abundance of lepidopterans north of the forest zone are discussed.     

Communities of phyllophagous insects in young birch greeneries of northern cities

Phyllophagous insect assemblages on birch trees have been studied in greeneries of the cities of Labytnangi and Salekhard and natural habitats in the environs of these cities in 2007, 2010, and 2013. The 44 recorded species were dominated by insects of the orders Lepidoptera and Hymenoptera (18 and 12 species, respectively); regarding feeding ecology and mode of life, they were dominated by open-living chewing phyllophages and miners (19 and 10 species). The urban greeneries and sparse birch forests were colonized by the same species, but the density of many species in the cities was considerably higher. The species composition of the communities changed considerably from year to year. The species richness and similarity of insect assemblages at the studied sites were the highest in 2013. The basic pests of birch in the northern cities were chewing phyllophages, especially Tenthredinidae sawflies.     

Taxonomy, phenology, and trophics of the urban macrolepidoptera feeding on trees and shrubs

A total of 107 macrolepidopteran species from 12 families have been recorded in 2006–2010 on trees and shrubs in the city of Yekaterinburg; in contrast to natural communities, no lasiocampids and few nymphalids have been found. The proportion of specialized species among the Macrolepidoptera living in the city is decreased, although the proportion of obligate dendrophagous species is increased. Differences in the phenology of lepidopterans living in urban greenery from those living in natural communities have been observed: a decreased proportion of autumn-spring species and an increased proportion of summer species. These differences can be explained both by relatively weak colonization of urban territory by facultative dendrophagous species with their specific seasonal strategies and by differences in methods used to collect the insects.     

Latitudinal Gradients of Trophics in Ural Macrolepidoptera: The Role of Food Quality

The Macrolepidoptera fauna of the Urals, from the southern to the northern boundary of the forest zone (i.e., from the forest–steppe of the Southern Urals to the forest–tundra of the Polar Urals) has been analyzed. It has been demonstrated that the proportion of Lepidoptera feeding on woody plants, including evergreens, increases in this direction. Among the Heterocera, the proportion of species feeding on graminoids decreases; in the Polar Urals, none of these species is specialized. The food spectrum is particularly variable in noctuids and almost invariable in geometrids and Rhopalocera. It is assumed that foods with a low nutrient value (grasses, mosses, lichens, plant debris, wood, and roots of various plants) prevent Macrolepidoptera species from spreading in the Subarctic region. In the Polar Urals, multiyear developmental cycles and wintering at the larval stage are related to feeding on these types of food.