The western conifer seed bug (Leptoglossus occidentalis Heidemann, 1910) is an invasive alien species from North America that causes significant economic losses by damaging cones and reducing seed yield in pines. The pest was first detected in Turkey in 2009, coinciding with increasing seed losses in many conifers, particularly Stone pine, Pinus pinea L. This study aimed to assess the impact of L. occidentalis on seed loss in three-year-old P. pinea cones. Conducted in 2020-2021 in P. pinea stands of the Izmir/Bergama Kozak Plateau, the experiment involved 5103 seeds collected from 30 cones, both caged (excluded) and uncaged (exposed), on 15 trees over two years in a natural setting. The seeds were first categorized by damage level using X-ray imaging, then subjected to a flotation test to determine the floating and sinking ratios. Subsequently, the kernels were manually examined to classify damage, and their weights were measured. The results showed that seed loss in excluded cones was significantly lower than in exposed cones, highlighting the impact of a factor that cannot reach excluded cones, with L. occidentalis as the most likely cause. X-ray, seed flotation, and naked-eye methods yielded similar results in assessing overall seed loss. Seed damage rates in the exclusion treatments were 17.6%, 17.0%, and 17.0%, respectively, whereas in the exposition treatments they were 46.2%, 48.0%, and 53.0%, respectively. As of 2021, these levels of seed loss corresponded to an estimated economic loss of approximately €55 per kg of seed. When damage levels were categorized, X-ray and naked-eye assessments produced inconsistent results. These findings suggest that X-ray, seed flotation, and naked-eye methods can be used interchangeably to determine overall seed damage. However, the naked-eye method appears to be more suitable for categorizing damage levels.
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Avci M, Oguzoglu S, Can T, Öçal F, Özçankaya IM, Ipekdal K (2026). Measuring the damage of Leptoglossus occidentalis in Stone pine seeds in a pine nut production hot spot in Turkey. iForest 19: 201-208. - doi: 10.3832/ifor4854-018
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Matteo Marchioro
Paper history
Received: Mar 20, 2025
Accepted: Nov 04, 2025
First online: Jun 04, 2026
Publication Date: Jun 30, 2026
Publication Time: 7.07 months
© SISEF - The Italian Society of Silviculture and Forest Ecology 2026
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