Impact of invasive species Parectopa robiniella (Gracillariidae) on fluorescence parameters of Robinia pseudoacacia in the conditions of the steppe zone of Ukraine

Abstract

Robinia pseudoacacia L. is one of the most common and environmentally adaptable introduced tree species which has become an important element of artificial afforestation and landscaping in Ukraine over the past 150 years. Throughout the history of its introduction on the territory of Ukraine, this species was considered resistant because of the absence of dangerous phytophages. At the beginning of the XXI century, the phytosanitary situation changed as the result of the penetration and rapid spread of a number of North American invasive phytophages. The appearance and distribution of the miner Parectopa robiniella (Clemens, 1863) (Lepidoptera, Gracillariidae) feeding on R. pseudoacacia was recognized as the largest invasion in Ukraine. This paper considers the issues of studying the effect of P. robiniella caterpillars feeding on R. pseudoacacia in various forest-growing conditions in the steppe zone of Ukraine. The process of photosynthesis, as the most important physiological parameter, was chosen as indicator of condition. The study was conducted using biosensor technology which made it possible to measure the effect of caterpillar feeding on critical parameters of chlorophyll fluorescence (the Kautsky curve). The research has shown that the initial value of fluorescence induction was within the range of 196–284 RFU, and the maximum value of the background fluorescence parameter was recorded in undamaged leaves and under shading conditions. Both the effect of phytophages and the shading factor caused a significant decrease in the values of fluorescence induction of the “plateau” both in the conditions of an artificially washed sandbar, on the watershed area of a watershed-gully landscape, as well as on natural sandy-loam soil. The maximum values of photosynthetic fluorescence induction under the simultaneous influence of the studied factors had rather high variability. In contrast to the fluorescence induction parameter, the “plateau” of the highest maximum fluorescence induction was reached in the absence of pest damage under conditions of total shading. As revealed by dispersion and regression analyses, the maximum fluorescence index was most dependent on the amount of solar radiation and on the degree of the leaf surface damage by phytophages. Significantly higher values of the steady-state fluorescence induction parameter were determined in the absence of insect damage in both shading and lighting conditions. A statistically significant combined influence of abiotic and biotic factors on the “plateau” fluorescence induction parameter was determined in comparison with the mono-influence of individual factors. A highly significant dependence of the maximum efficiency indicator of primary photosynthesis processes on individual factors of exogenous influence was established, while the combined effect of these factors did not affect this parameter. The obtained data allow one to apply in practice the methods of analyzing chlorophyll fluorescence induction to establish the physiological state of tree flora in forest and garden farms.

Dependence of some physiological indicators of generative and vegetative organs of Sambucus nigra on habitat conditions

“…We examined water deficit and relative turgidity of leaves and fruits, and these parameters varied with altitude. Other researchers are also engaged in the study of water regime of the plants (Gritsan et al, 2019;Jagosz et al, 2019) and influence of water deficiency or pests (Holoborodko et al, 2021(Holoborodko et al, , 2022a(Holoborodko et al, , 2022bShupranova et al, 2021) on the physiological condition of the plants. The water circulation of elderberry plants principally depends on the conditions of the atmosphere (Tökei et al, 2005).…”

Steppe vegetation islands in the gully landscape system: Hemeroby, naturalness and phytoindication of ecological regimes

“…Steppes and semi-natural grasslands of the temperate zone are under great threat due to several global processes, such as climate change (Erdős et al, 2018), spread of invasive species (Holoborodko et al, 2022), land use changes and urbanization (Tsvetkova & Saranenko, 2007Saranenko, 2011;Robinson, 2013;Faly & Brygadyrenko, 2014;Brygadyrenko, 2015;Tsvetkova et al, 2015). Arid and semi-arid steppes are particularly sensitive to climate change.…”

Elm (Ulmus) leaf miners in North-East Kazakhstan

“…The main reasons for the leaf miners' migration are global processes, the openness of markets, rapid changes in response in economic relations between countries, often located in different parts of the world (Holoborodko et al, 2022). The listed factors contribute to the penetration of organisms that are not typical for certain geographical regions of the world.…”