On assessment of the large-scale effect of introduction of the ragweed leaf beetle Zygogramma suturalis F. (Coleoptera, Chrysomelidae) on the phytocenoses of South Russia

Evaluation of the efficiency of large-scale projects of phytophage introduction for weed control is of importance for both the theory and practice of biological control. Introduction of the ragweed leaf beetle Zygogramma suturalis F. into the USSR in the 1960–80s is an example of such a project. The main theoretical result of this project was the discovery of the phenomenon of the solitary population wave (SPW), which is a necessary condition for successful biological control of the invasive weed. Recent investigations confirm the long-term efficiency of acclimation of the common ragweed phytophages in the South of Russia. The disappearance of a huge phytomass of the common ragweed in the fields, an abrupt drop in the seed density in the soil, reduction of the infestation areas, and absence of large and dense weed patches in satellite images testify to the fact that the goal of phytophage introduction, i.e., suppression of the common ragweed in agrophytocenoses, has been met. The tasks of the next phase of ragweed suppression are discussed in view of the role of the common ragweed as a synanthropic allergic agent and a ruderal plant growing in anthropogenically transformed territories.