Invasive Species Compendium

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Abstract

The leaf surface damage of horse chestnut caused by the horse chestnut leaf-miner larvae in Belarus after the completion of the invader's expansion.

Abstract

The horse chestnut leaf-miner (Cameraria ohridella Deschka & Dimič, 1986) is an invasive alien species in the fauna of Belarus, belonging to the family Gracillariidae (Insecta: Lepidoptera), the main pest of Aesculus hippocastanum L. (Sapindales: Sapindaceae) in green areas in Belarus. The annually observed C. ohridella population outbreaks lead to the fact that the crowns lose their natural appearance and defoliate earlier, that affects the decorative and recreational qualities of green areas catastrophically. Based on the data of long-term (2013-2019) studies, a quantitative assessment of the relative square of the damaged by horse chestnut leaf-miner larvae leaf surface of horse chestnut trees in green areas in all 5 regions of woody plants introduction in Belarus is given. A wide range of variation in the values of the indicator of the relative area of the damaged leaf surface has been observed: in the range from 2.97% to 89.45% for Belarus as a whole, as well as for individual settlements, for example, from 18.43% to 58.25% for Vitebsk or from 15.60% to 89.45% for Pinsk. The samples from several areas of introduction of woody plants were characterized by coefficients of variation from 50.66 to 67.76. The use of Kruskal-Wallis test did not reveal statistically significant differences between the data from different areas of plant introduction in Belarus excluding the comparison pairs North/West and West/North-Central introduction-dendrological areas. At the same time, for a number of cities in the country, using the non-parametric Wilcoxon signed-rank test, the statistical reliability of the increase in the relative damage to the leaf surface of A. hippocastanum in 2019 in comparison to the 2016 data, was shown. In the conditions of green spaces in Minsk in 2013-2019 the oscillations of the examined indicator were observed, whereas in green spaces in Grodno in 2016-2019 a progressive increase in the relative area of the leaf surface of horse chestnut damaged by C. ohridella larvae was indicated, which can be explained by the "accumulation effect" of the invader in the absence of withdrawal of the overwintering reserve of the pest population during the removal of leaf litter with hibernating miner pupae in autumn.