Evaluating Lymantria dispar Mating Disruption in Southeastern Europe via Male Flight Activity and Egg Clusters

The spongy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), is one of the most destructive defoliators, primarily of oak forest ecosystems, causing severe ecological and economic damages. The present study evaluated the effectiveness of the mating disruption method against L. dispar populations in an oak-dominated forest in Greece. Field experiments were conducted for three consecutive years (2022–2024) in two forest areas: a treated area, where a flowable pheromone gel was applied, and an untreated control area. The L. dispar male flight activity was monitored using pheromone-baited traps. Egg cluster counts were assessed during winter to evaluate reproductive success. The obtained results revealed a significant reduction in male trap captures in the treated area, following the mating disruption application in 2023 and 2024, compared to the control area. Additionally, the egg cluster counts decreased significantly in the mating disruption area, reaching reductions of 94.8% and 99.2% during the winters of 2023–2024 and 2024–2025, respectively, compared to the winter of 2022–2023 (before the mating disruption application). These results demonstrate that mating disruption, an environmentally friendly strategy for sustainable forest pest management, can effectively reduce L. dispar populations under Mediterranean environmental conditions.