Trophic Relationships of Phytophages with Invasive Plant Species in Central Russia

The aim of the study was to identify phytophages belonging to Insecta and Gastropoda that form trophic relationships with invasive plant species in Central Russia. The adaptation of phytophages to 15 invasive species included in the TOP-100 was evaluated. We identified 42 species of phytophagous insects belonging to 20 families of five orders: Coleoptera (14 species), Lepidoptera (13), Diptera (5), Hemiptera (5), and Homoptera (5 species). Mollusks (Helicigona lapicida L. and Physa fontinalis L.) are adapted to five invasive plant species. Among insects, polyphagous ones (76%) are predominant in terms of specificity, with lesser participation of oligophagous (19%) and sporadic participation of monophagous ones (5%). In terms of feeding type, most phytophagous insects belong to the group of gnawing insects (32 species), while sucking and mining insects account for five species each. The long-term monitoring of 15 invasive species revealed the gradual formation of a damaging trophic complex of autochthonous phytotrophic entomofauna and mollusks that switch to invasive species from plants of close taxonomic groups. No significant correlation was found between the time of occurrence of an alien species and the number of phytophagous species adapted to it. The rate and success of adaptation of phytophages to naturalizing alien species is determined by ecological conditions, the effect of anthropogenic factors, the age of plantations, and the presence of native or widely cultivated species close in taxonomy in nearby ecotopes. Thus, the “natural enemies” hypothesis is true only at the initial stage of naturalization. Later on, polyphagous pests of closely related native or widely cultivated species are actively included in the complex “invasive species–phytoconsort.” Taking into account the fact that most of the cases involve minor, often isolated damage to invasive plants, further study of phytoconsorts is required to better understand the stability of trophic relationships in biocenoses.