Monitoring the population of the horse chestnut leaf miner in the Pskov Region

This paper discusses the findings of observations on the population of an invasive species in the Pskov Region, namely, horse-chestnut leaf miner (Cameraria ohridella Desch. & Dimic). The horse-chestnut leaf miner causes serious damage to the ornamental plants, it causes their weakening. Horse chestnut trees are under a threat of widespread damage and drying-up due to the destructive activity of the horse-chestnut leaf miner. The main indices characterizing the pest population are studied: occurrence, leaf colonization and population density. The long-term dynamics of occurrence and harmfulness of the pest in the area are discussed. It is found that the pest began to spread across the landscaping sites in the City of Velikie Luki since 2012. Over the following five years, the occurrence and numbers of the horse-chestnut leaf miner increased sharply. The pest began to present a significant threat to the chestnut trees in Velikiye Luki and the surrounding area since 2017. Currently, the pest has infested all chestnut plantings in the City of Velikie Luki and its environs; the pest incidence and leaf infestation are in fact 100%. The laminas that are damaged by more than half make the largest part of the samples (up to 92%). Using synthetic sex pheromones, the observations were made of the flight of adult horse-chestnut leaf miners. The dynamics of the horse-chestnut leaf miner flight during the development of two and three generations is analyzed. Some mechanisms of adaptation of the pest to the impact of abiotic factors are revealed such as the formation of a facultative third generation and wintering of part of the population in the imago stage. Active dispersal, spread and acclimatization of the horse-chestnut leaf miner as well as its increasing harmfulness require regular monitoring of pest population indices.