Characteristics of artificial forest belts invasion by Parectopa robiniella (Clemens, 1863) (Gracillariidae stainton, 1854) in Dnipropetrovsk oblast

Abstract

We studied characteristics of invasion by Parectopa robiniella Clemens, 1863 the black locust (Robinia pseudoacacia Linnaeus, 1753) plantations used for field protection and anti-erosion purposes on the example of an artificial forest belt in Mayorka village in Dnipropetrovsk district, Dnipropetrovsk Oblast (Mykilsky Forestry of the Dnipro Forest Enterprise). Monitoring surveys were conducted during the growing seasons of 2014–2021. The invasion of field-protective forest belts does not appear evenly; we found that the tree age is the main factor in this process. Because black locust plantings occupy the most significant area among artificial field-protective plantings in Ukraine, we studied the characteristics of their invasion by the insect species. It was found that R. pseudoacacia manifests itself relatively actively in almost all natural zones in Ukraine, mainly due to its spread by root growth. The forest belt surveys allowed us to distinguish three age-related variants of R. pseudoacacia trees (initial trees planted in composition of a forest belt (50–70 years), sprouting trees (15–25 years), and young trees (up to 15 years)). Monitoring surveys have shown varying degrees of P. robiniella invasion of three age groups of trees. It was discovered that the invader mainly develops mines on the leaves of young trees (up to 15 years old). According to the results of calculating the average number of mines on a simple leaf, it turned out that P. robiniella most often formed the mine on the lower (near the petiole) leaf segment in all three age tree groups. Determination of the characteristics of the relative invasion of simple leaflets from the total number of damaged leaflets showed that the invasion of the leaf blade was highest within the location of the middle leaflets on Robinia complex leaf. Such characteristics of invasion can be explained by the different growth rates of R. pseudoacacia leaf blade and the quality characterization of leaf tissues. Thus, our survey confirmed the assumption of O. V. Sinchuk (2016) that the topical specificity of invasion derived from the peculiarities of divergent leaf development and acropetal leaf development of the feeding plant.