The introduction of wood-boring insects to non-native areas can pose a significant threat to global forest ecosystems. Aromia bungii and Massicus raddei, native to Asia including Korea but potentially important in urban forestry worldwide, are severe trunk borers that have recently infested host trees in urban landscapes of Korea. The signs of external injury can help identify cerambycid-infested trees. However, assessing the internal condition of trees without causing damage is challenging, which hinders the management of infested trees that are still alive. This study evaluated the potential use of sonic tomography to assess injury characteristics in the woody parts of trees, such as Prunus × yedoensis and Quercus palustris infested by A. bungii and M. raddei, respectively. Among the 45 investigated trees, the number of holes on external parts was recorded by visual examination. Sonic tomography images revealed decayed areas, allowing for a comparison of internal damage between infested and non-infested trees. The internal status of trees infested by the two cerambycid beetles differed from that of healthy trees. While some healthy trees exhibited minimal internal damage, those that were not infested by beetles showed decayed areas, potentially caused by non-biological factors such as frozen cracks. In conclusion, sonic tomography equipment can potentially be used for non-invasive assessment of internal injuries caused by wood-boring insects in urban trees.

The walking-stick insect Ramulus mikado is occasionally considered a forest pest, as its mass occurrence can cause severe defoliation. It overwinters as eggs on the ground surface, and the hatched nymphs climb up to the host trees in spring. In this study, temperature-dependent development experiments were performed on R. mikado eggs under three constant temperatures (23.3, 28.3, and 29.2 °C) to extend the previously reported thermal response. The development times of eggs collected in summer and winter were also compared to investigate how development status is influenced by the seasons. The lower and upper developmental thresholds and thermal constants of R. mikado eggs were estimated to be 6.1 °C, 29.2 °C, and 1707.8 DD, respectively. The starting point for effective temperature effects on the eggs was estimated to be 1 August, based on the results of the experiment on field-collected eggs. A phenology model was constructed by using a development completion model scaled by the thermal constant, with a starting point of degree-day accumulation. The model showed good agreement, with a deviation of 3.2 ± 2.95 days between prediction and observation. The developed phenology model is useful for determining the appropriate timing for management decision-making regarding this insect.

Numerous Calanthe (Orchidaceae) species are considered food-deceptive orchids because they attract floral visitors without providing rewards. In this study, we investigated floral visitors and their different types of behaviour in natural populations of Calanthe discolor and C. striata in South Korea during peak flowering to identify pollinaria-carrying visitors and assess whether the observations suggest potential pollinator sharing between the two taxa. A total of 73 visitation events involving 17 insect species were recorded on C. discolor . Diptera accounted for most visitation events, but no dipteran or lepidopteran visitors carried pollinaria. Pollinaria attachment was confirmed only in hymenopteran visitors ( Andrena opacifovea , Apis cerana , Ceratina japonica and Lasioglossum formosae ) that probed deeply into the spur. In C. striata , a single visitation event by Eucera nipponensis was recorded and the observed individual carried pollinaria on the head and transported them between flowers. This observation is consistent with previous reports from Japan and suggests a possible mechanism of pollinator sharing that should be tested through broader temporal and population-level observations. The results reveal a clear mismatch between visitation frequency and pollinaria transport in C. discolor , with pollinaria attachment restricted to a subset of bee visitors. Together with previous studies, our findings support a generalised food-deceptive pollination strategy in C. discolor mediated by locally available bees. This study provides baseline field evidence on floral visitors and pollinaria transport in Korean Calanthe and establishes testable hypotheses for future studies of reproductive interactions amongst closely-related taxa.