One of the subspecies of the Eurasian spongy moth, Lymantria dispar asiatica, is a destructive forest pest in native regions and also an important quarantine pest in non-native regions. Its polyphagous nature, together with occasional outbreaks, may seriously threaten ecosystems and result in costly management programs. In this study, we examined the effect of chilling temperatures (−12, −6, 0, 6, and 12 °C) during the diapause phase on the survival and post-diapause development of L. d. asiatica eggs, collected before winter, in order to characterize their thermal response. The eggs were exposed to treatment temperatures for 100 days, followed by 25 °C incubation to determine their survival and development time. The eggs hatched in all the treatments, indicating that all the examined conditions could partly or sufficiently satisfy the thermal requirement for eggs to enter post-diapause development. However, exposure to chilling temperatures significantly affected both the survival and development times of overwintering eggs in a given temperature range. The survival rates declined at −12 °C, and the development rates accelerated as the chilling temperature increased. This information could offer clues for the assessment of the outbreak potential in native regions and the possibility of range expansion in non-native regions through the consideration of winter conditions that favor L. d. asiatica egg hatching and their subsequent development.

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.

Urban expansion threatens ecosystems through direct habitat conversion. To secure urban biodiversity and enhance ecosystem services, a common focus of planning and growth management efforts is to establish green spaces. This study aimed to understand the formation process of newly created green spaces after urban development. We investigated the carabid beetle assemblages in its current habitat in a new city and in its former habitats for assessing the loss of species diversity by urban development and to identify the initial status of species assemblages in the current urban habitats, including green spaces. The diversity and composition of the carabid beetle assemblages significantly changed in the new city. The former habitat loss by urban development leaves large numbers of carabid species to dramatically decline. Carabid assemblages in current habitats may show a critical response to habitat loss, although former habitats were converted to green spaces. Some carabid species were only present in current habitats, including the green space from former habitats. In addition, the current habitat, including green spaces and other habitats, have similar carabid assemblages. Our results indicated that the loss of former habitat has a much greater effect on species diversity persistence than changes in habitat configuration and the creation of green spaces. Consequently, most carabid beetles were already lost during development. Urban habitats in new cities, including green spaces, represent simple and homogeneous habitats, although the development was designed and planned to enhance biodiversity. The present design and planning practice for green spaces that destroyed all former habitats to prepare the ground of urban areas and thereby created urban habitats, including green space, may need to be changed to secure biodiversity. Designing and planning the green spaces should consider the species’ former habitats, for instance, creating a similar type of green space to agricultural land, forest, and wetland, and thereby the former habitat remains intact to enhance biodiversity and function.

Spatial and temporal variation in ecological environments may result in spatial and temporal variation in communities. Temporal studies of biodiversity are essential for forecasting future changes in community structure and ecosystem function. Therefore, determining the mechanisms that drive temporal change in communities remains an important and interesting challenge in ecology. We quantified spatial and temporal variations in carabid beetle communities and site-specific environmental factors for 5 years at nine study sites on three mountains in the Baekdudaegan Mountain Range, Korea. Carabid beetle communities exhibited significant temporal variation, which was larger than spatial variations between and within mountains. Environmental factors mostly varied between sites within mountains. Community variation was only weakly associated with environmental factors at wide scales, i.e., between sites on three mountains, but was strongly associated at narrow spatial scales, i.e., between sites within one mountain. Our results indicate that temporal variation in communities occurs in response to variations in the local climate, and that the patterns of temporal variation differ between mountains. Thus, temporal surveys of insect communities and climates at local scales are important for predicting temporal changes in the communities.

This study aims to construct essential information on the pests attacking Cnidium officinale Makino, which is one of the most important medicinal plants in Korea and neighboring countries. Based on the current survey, a total of 12 species were identified, including three above-ground pests attacking flowers, leaves, and stems, as well as ten soil pests attacking roots. In the vertical distribution of damaged roots, the dominant species is bulb mite (Rhizoglyphus robini) followed by onion maggot (Delia antiqua). Based on this study and the previous literature, the total number of species of pests reported to attack C. officinale is 36, including 3 on flowers, 16 on leaves, 6 on stems, and 11 on roots. We also investigated and compiled a list of natural enemies based on all available information and the current study, totaling 14 species. Parasitus sp., Macrocheles glaber, and Smicroplectrus sp. were identified as candidate natural enemies of root pests.