Seasonal Abundance and Distribution of Empoasca vitis (Hemiptera: Cicadellidae) on Grapevine and Associated Natural Enemies

Abstract

Seasonal abundance and spatial distribution of Empoasca vitis (leafhopper) and its associated natural enemies were investigated in grapevine agroecosystems to understand pest dynamics and enhance integrated pest management strategies. Field surveys were conducted across multiple vineyards during different phenological stages of grapevine growth, and insect populations were monitored using sweep netting, yellow sticky traps, and direct leaf sampling. Results indicated that E. vitis populations exhibited distinct seasonal fluctuations, with peak abundance occurring during warm and dry periods coinciding with active vine vegetative growth. Population buildup was strongly influenced by temperature, relative humidity, and host plant phenology, with higher infestation levels observed during late spring and summer months. Spatial distribution analysis revealed aggregated patterns of leafhopper occurrence, particularly in vineyard blocks with dense canopy and reduced air circulation. Several natural enemies, including predatory coccinellids, chrysopids, and hemipteran predators, as well as parasitoid species, were recorded in association with E. vitis populations. The abundance of natural enemies showed a positive correlation with prey density, indicating a density-dependent response. Vineyards with reduced insecticide application supported higher diversity and abundance of natural enemies, contributing to partial regulation of leafhopper populations. However, natural suppression alone was insufficient to prevent economic damage under high pest pressure conditions. The study highlights the importance of environmental factors and agronomic practices in shaping pest–natural enemy interactions in grapevine systems. Understanding seasonal dynamics and distribution patterns of E. vitis and its biological control agents is essential for optimizing timing of management interventions.