Defoliating insects active in early spring, such as Tortrix viridana and certain Geometridae species, can reduce fruit production by consuming flower buds or inducing physiological imbalances that disrupt floral induction and acorn development. Although Tortrix viridana is polyphagous, it exhibits a marked preference for oak (Quercus spp.). However, under conditions of food scarcity, mature larvae may switch to alternative hosts, including apple (Malus domestica) and pear (Pyrus communis), especially in orchards. Despite its ecological and economic relevance, data on the species’ dynamics in western Romania are limited. Therefore, this study aimed to monitor the population dynamics of Tortrix viridana in Timiș County in relation to host plant type and climatic conditions, with additional focus on vertical distribution within the tree canopy. Fieldwork was conducted during the 2022 season at two sites: a family orchard in Dudeștii Noi and the USVT experimental park in Timișoara. Adult moths were monitored using Delta traps baited with atraVIR pheromone lures, while larvae were quantified via the “100 leaves” method, with sampling from three canopy levels. Results revealed clear host-dependent variability. Apple trees recorded the highest larval and adult densities, suggesting an emerging trophic shift toward cultivated hosts. Although ANOVA did not indicate statistically significant differences, this trend was supported by post-hoc analysis and high variability, especially in apple plots. Additionally, population peaks coincided with specific climatic windows, underscoring the role of microclimate in phenological development. These findings support the hypothesis of behavioral adaptation in Tortrix viridana and highlight the need for targeted monitoring and predictive models in orchard ecosystems.

Tortrix viridana, oak, apple, pear, orchards, pheromonal traps

agronomy

Presentation: poster