Invasive alien insects cause serious ecological and economical losses around the world. Here, we review the bionomics, modern ranges (and their dynamics), distribution pathways, monitoring, and control measures of 14 insect species known to be important invasive and emerging tree pests in forest and urban ecosystems of Russia: Leptoglossus occidentalis (Hemiptera: Heteroptera: Coreidae), Halyomorpha halys (Hemiptera: Heteroptera: Pentatomidae), Corythucha arcuata (Hemiptera: Heteroptera: Tingidae), Agrilus fleischeri, A. mali, A. planipennis, Lamprodila (Palmar) festiva (Coleoptera: Buprestidae), Ips amitinus, Polygraphus proximus (Coleoptera: Curculionidae: Scolytinae), Cydalima perspectalis (Lepidoptera: Crambidae), Acrocercops brongniardella, Cameraria ohridella, Phyllonorycter issikii, and P. populifoliella (Lepidoptera: Gracillariidae). We identified three major scenarios of tree pest invasions in the country and beyond: (1) a naturally conditioned range expansion, which results in the arrival of a pest to a new territory and its further naturalization in a recipient region; (2) a human-mediated, long-distance transfer of a pest to a new territory and its further naturalization; and (3) a widening of the pest’s trophic niche and shift to new host plant(s) (commonly human-introduced) within the native pest’s range frequently followed by invasion to new regions.

Results from the study of ecological features of the alien bark beetle P. proximus in the West Siberian invasion region are presented in the article. Its basic habitats, biology, and demographic features are established. In the outbreak foci, new trophic links of this invader with the Siberian spruce, Siberian stone pine, and Scots pine, as well as its natural enemies, are revealed.

The reproductive behavior of the four-eyed fir bark beetle Polygraphus proximus Blandf., an invasive pest of the Siberian fir, was studied. Monogyny of this species was demonstrated in an experiment with colonization of fir logs by groups of adults with a given sex ratio. The female of P. proximus can build several egg galleries and has a mean fecundity of 45 ± 15 eggs. The main elements of intraspecific (reproductive and agonistic) behavior of P. proximus inside the galleries are described in detail. The four-eyed fir bark beetle has some behavioral patterns which are typical of more advanced species of the same genus, such as male entry hole initiation. Comparative analysis of the reproductive behavior and phylogenetic studies of the representatives of the genus Polygraphus Erichson may clarify the functional role of evolutionary transition from monogyny to polygyny in bark beetles.

The small spruce bark beetle Ips amitinus is a widespread species in many European countries that has been actively spreading into Northern Europe in the recent decades. In Russia, I. amitinusis...