Population Parameters and New Records of the Emerald Ash Borer Agrilus planipennis Fairm. (Coleoptera, Buprestidae) in Saint Petersburg in 2022

Updated results of studying the secondary population of the emerald ash borer Agrilus planipennis (EAB) in St. Petersburg and its environs are reported. Our data show that the pest population is currently persisting in St. Petersburg, posing the danger of mass destruction of ash stands, which play a very important role in urban vegetation. Felling of infested ash trees at two detected outbreak sites has stopped further reproduction of EAB in these areas, while reproduction of the pest continues at three other sites. Repeated examination of model trees at the outbreak site in Nevsky District showed an increase in the pest population density. The EAB survival rate remained approximately at the same level as in 2020. The population density of the pest increased with the height of the trunk area along the infested tree. The role of parasitoids in controlling the EAB abundance was insignificant. Larvae, pupae, and adults were simultaneously found in the wood of the infested plants. The life cycle of EAB in St. Petersburg seems to depend considerably on the weather conditions and the microhabitat features, the higher sum of effective temperatures being the key factor of successful development. Infestation becomes detectable by visual examination only after the emergence of the first adults, which leave conspicuous exit holes. A considerable part of the population remains in the wood as larvae and pupae after emergence of the adults; therefore, the main method of controlling the EAB spread is timely detection and removal of trees with exit holes. Another effective method would be introduction of specific EAB parasitoids, which are currently virtually absent in the local pest population. Constant monitoring of ash trees is necessary, primarily at the known outbreak sites in Petrodvortsovy and Nevsky districts. Prevention of further EAB dispersal requires active involvement of all municipal and federal management structures responsible for city plantings.