Adventive leaf-mining insects in the green stands of Zhytomyr

Abstract

Introduction

Urban green stands perform important ecological functions, but at the same time they are more vulnerable than forests to any adverse factors, in particular to insect damage. Recently, the health condition of such stands has noticeably deteriorated, primarily due to climate change and anthropogenic pressure. Alien species of phytophagous insects, in particular leaf miners, have penetrated the green stands of many regions. Measures to prevent harmful effects of insect miners should be based on the study of the characteristics of their occurrence and biology. The most common alien insect miners in urban stands are Cameraria ohridella Deschka & Dimi?, 1986, Phyllonorycter issikii (Kumata, 1963), and Parectopa robiniella (Clemens, 1863).

The aim of the research was to reveal the features of occurrence and seasonal population dynamics of alien leaf-mining insects in the green stands of Zhytomyr.

Materials and Methods

The study was carried out in 2020 in the parks (Yu. Gagarin and 30-Richchia Peremogy), in the streets of the center (Peremoga Avenue, Kyivska and Velyka Berdichevska Str.) as well as in the streets of the industrial zone (Koroliov and Paradzhanov Str.). Taking into account the results of surveys obtained in 2019, starting from the 1st decade of May in 2020, 100 randomly selected leaves were collected every decade from small-leaved lime, horse chestnut, and black locust trees, and placed in separate bags with labels. During the processing of the collected samples, the number of mines of insect miners on each leaf was counted and the average density of mines per leaf was evaluated. The occurrence of miners on each tree species was evaluated as the average proportion of leaves with the presence of mines. The dates of the appearance of eggs, caterpillars, pupae, and adults of the studied insect miner species were recorded.

Results and Conclusions

Occurrence and seasonal dynamics of population density for three species of adventive leaf-mining insects from Lepidoptera: Gracillariidae: Cameraria ohridella Deschka & Dimi?, 1986 on the horse chestnut, Phyllonorycter issikii (Kumata, 1963) on the small-leaf lime, and Parectopa robiniella (Clemens, 1863) on the black locust – were studied in the park and street stands of Zhytomyr. Three maximums of chestnut miner density (in the 2^nd decade of June, the 2^nd decade of July, and the 3^rd decade of August), two maximums of a lime miner (in the 2^nd decade of June and the 2^nd decade of August), and three maximums of a black locust leaf miner (in the 2^nd decade of June, the 2^nd decade of July and the 2^nd decade of August) were registered. In the spring, the density of the horse chestnut miner population was the lowest in the parks and streets of the center, where fallen leaves had been removed since autumn. The size of the damaged area of horse chestnut leaves was influenced not only by the density of the horse chestnut miner population but also by fungal infestation and technogenic pollution.

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