THE MOSAICITY OF HABITATS AS A FACTOR OF STABILITY OF THE POPULATION OF DIMORPHOPTERUS SPINOLAE (HETEROPTERA, LYGAEIDAE) IN THE PROCESS OF POSTPYROGENIC SUCCESSION IN THE EAST-EUROPEAN FOREST-STEPPE

Based on the results of quantitative surveys conducted from 2021 to 2024, the dynamics of abundance and spatial distribution of the xerophilic species – the bug Dimorphopterus spinolae Signoret (1857) (Heteroptera, Lygaeidae) – were studied on a former fire site in the Usmansky Forest (Voronezh Region), formed after the 2010 fire. The formation of a stable population grouping of the species was established. Significant interannual fluctuations in abundance were revealed, with a peak in 2021 followed by a subsequent decline. During the period of maximum abundance, its average values ranged from 10.88 (in the Calamagrostis-Chenopodium association) to 17.88 (in the Festuca-Calamagrostis association) individuals per 100 sweeps with a standard net. In 2023, with the minimum abundance of the species in different plant associations, it decreased by 2.6–11 times. The main limiting factors for the abundance of D. spinolae were high temperature maxima and prolonged drought periods. These factors led to premature drying and hardening of the vegetative parts of the main food plant, Calamagrostis epigeios, which worsened its quality for feeding the nymphs and adults of the bug. The greatest decline in the abundance of D. spinolae was noted in the most xerophilic area occupied by the Festuca-Calamagrostis association (1.63 individuals per 100 sweeps). Under prolonged abiotic stress towards xerophily, more mesophytic conditions ensured better preservation of the food base and a more favorable microclimate, providing for the preservation of the local population grouping of the species. The obtained data indicate the naturalization of the typical meadow-steppe species, the bug D. spinolae, in the conditions of a forming xerophilic biotope in place of the fire site and reflect the general trend of xerophily in the post-fire ecosystem in the Eastern European forest-steppe zone.