RELATIONSHIP OF DENDROBIONTIC INSECTS, FUNGI AND NEMATODES AND THEIR ROLE IN THE WEAKENING AND DEATH OF HOST PLANTS
A. V. Selikhovkin1, A. Yu. Ryss2, D. A. Shabunin1,3, V. V. Anton’1, M. B. Martirova1, M. Yu. Mandelshtam1
1Federal State Budgetary Educational Institution of Higher Education «Saint-Petersburg State Forest Technical University», Saint Petersburg, Russian Federation
2Zoological Institute, Russian Academy of Sciences, Saint Petersburg, Russian Federation
3Saint-Petersburg Forestry Research Institute, Saint Petersburg, Russian Federation
Keywords: bark beetles, phytopathogenic fungi, stem nematodes, associations, woody plants, infection routes
Abstract
The interactions in the association of bark beetles, fungi, nematodes with the host tree is a multi-level system of transmission and trophic links that ensure the labile nature of disease scenarios leading to tree death. Transmission of phytopathogenic fungi and stem nematodes by bark beetles often acts as a key factor in the weakening and death of woody plants in forest and park plantations. Nevertheless, the nature of the interaction of various organisms in this four-component complex is species-specific and the role of transmission pathogens in the weakening and death of the host tree is far from always clear. To test this thesis, in our opinion, it is necessary to ensure a combination of field and experimental studies of the role of each infection agent - bark beetles, phytopathogenic fungi, and nematodes in weakening the tree with different sequences of colonization by members of the pathogenic association. Field studies should record seasonal changes in the dynamics of the number of pathogens in the tree and the vector in order to compile a model-diagram of infection. Experimental studies should test the scenarios of pathogen interaction in the vector-fungus, vector-nematode, nematode-fungus subsystems, as well as experiments on inoculation of fungi and nematodes into a plant, bypassing the vector and through the vector. Comparison of these data will make it possible to build a reliable regional predictive model of the infection scenario as a basis for developing practical measures to control diseases of woody plants. In 2023 and 2024, we began a series of studies to study the transmission of fungi and nematodes by bark beetles at different stages of the life cycle of two species of bark beetles, the most common in the taiga forests of the northwest of the European part of Russia - the European spruce bark beetle ( Ips typographus (Linnaeus, 1758)) (spruce ( Picea A. Dietr.)) and the Common pine shoot beetle ( Tomicus piniperda (Linnaeus, 1758)) (pine ( Pinus L.)). The results obtained show the high lability of the relationships between phytopathogens and bark beetles and the ambiguity of the role of bark beetles in the transmission of phytopathogenic fungi.
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