Ecological analysis of pest and disease dynamics in urban plant ecosystems

Abstract

Urban ecosystems are characterized by altered environmental conditions that significantly affect plant health, pest
abundance, and pathogen dynamics. Monitoring conducted in Tbilisi, Georgia, from 2023 to 2025 revealed high diversity and
pronounced spatial and temporal variation of plant pests and diseases across different urban green spaces, including parks, street
trees, botanical gardens, and private yards. Several dominant insect pest groups, including representatives of Ceroplastes,
Pulvinaria, Tetranychus, Eulachnus, and Corytucha, were consistently recorded, with peak population densities occurring in
late spring and summer. Some pest species completed multiple generations per year in warmer and sheltered microhabitats.
Fungal diseases were the most prevalent plant health issues, with frequent detection of Cytospora, Phomopsis, Diplodia,
Sphaeropsis, Alternaria, and Fusarium, whereas bacterial and viral diseases were less common. Seasonal trends were evident:
insect abundance increased with elevated air and soil temperatures, reflecting the urban heat island effect, while fungal disease
severity was associated with higher relative humidity, reduced air circulation, and soil conditions, including moisture,
compaction, and pH, which influenced both pest abundance and disease incidence, particularly in enclosed urban sites. Statistical
analyses demonstrated strong positive correlations between pest abundance and abiotic factors such as temperature and soil
moisture, and between disease severity, soil compaction, and microclimatic stress. Vegetation structure, biodiversity, and
connectivity influenced pest and disease dynamics, with fragmented and low-diversity green spaces exhibiting higher pest
abundance and disease incidence. The abundance of natural enemies was reduced in isolated urban patches, contributing to
frequent pest outbreaks. Urban stressors, including pollution, traffic, and human-mediated plant movement, facilitated the
introduction and spread of invasive pests and pathogens. These findings highlight the complex interactions of biotic and abiotic
factors shaping urban plant health and provide insights for developing ecologically informed management strategies to enhance
the resilience of urban green spaces.