Process-based models are effective in addressing spatially explicit dispersal of invasive species based on life mechanisms including birth, death, movement and response to environmental factors. An invading alien species, the western conifer seed bug (Leptoglossus occidentalis), spreads rapidly in the Korean peninsula since 1988. Process-based models were developed to include the rules occurred in population dynamics of the western conifer seed bug population. Passive movements were additionally linked to the models to present local and global transportations due to sapling trades. Simulation results presented the rapid dispersal of the pest species, comparable to field data. Model parameters including the Alle effect threshold and contribution of global transportation were adjusted to reveal spatially-explicit advancement patters of the species. Utilization of process-based models is further discussed in monitoring and management of forest insect pests in field conditions.

Recently, as the possibility of unexpected outbreaks of alien insects has increased due to climate change such as global warming, the importance of early control through rapid and accurate spread of exotic forest pest and change prediction diagnosis is required. This study summarizes and reports the followings: the establishment of monitoring strategy for exotic insects by the investigation of species distribution range through field surveys and others, the development of new diagnostic technique through microstructures and life-cycle, the dispersal of exotic insects, and ecological impact assessment using ecological methods and with the expansion of exotic insects and development of ecosystem impact prediction model.

Investigating loci compositions by conventional methods is limited in fully addressing complex gene information. We applied self-organizing map (SOM) to characterize Amplified Fragment Length Polymorphism (AFLP) of aquatic insects in six streams in Japan in responding to environmental variables. Locus band presence patterns were clustered by the trained SOM. Presence and absence data of loci were altered and cluster change through recognition was Subsequently expressed to indicate sensitivity to environmental variables. The outlier loci were determined based on the 90th percentile. Subsequently environmental responsiveness was obtained for each outlier in different species. Outlier loci were overall sensitive to pollutants and feeding material. Poly-loci like responsiveness was detected in adapting to environmental constraints. SOM training combined with recognition could be an efficient means of characterizing loci information without knowledge on population genetics a prior.

Intermediate disturbance hypothesis is one of important hypotheses for presenting the diversity patterns under disturbances. To investigate the diversity patterns of benthic macroinvertebrate communities under various disturbances, we collected macroinvertebrates in 47 sites representing various habitat types as well as pollution gradients in Southeastern Korea in summer and winter. Environmental variables such as depth, velocity, substrate and conductivity, and biological water quality indices (e.g., BWMP) were measured to show the intensity of disturbance in each site. Species abundance distributions (SADs) which are one of the efficient ways to assess community structure states based on macroecology were also considered to represent the pollution status based on the community patterns along an established pollution gradient. The community patterns were broadly divided into log-normal distribution and geometric series groups according to SAD models with weak and strong disturbance, respectively. According to the application of physicochemical water quality variable (conductivity), the gradient of community indices showed higher values on the intermediate disturbance state. Higher values of community indices, however, were presented on the low disturbance state with the gradient from BMWP. The parameters of SAD models, log-normal distribution, γ, and geometric series, k, were additionally calculated and compared with the traditional community indices.

Distribution of aquatic organisms is governed by various environmental factors Hydromorphological characteristics which are heavily affected by heavy rains in stream are one of the fundamental factors to influence the distribution of aquatic organisms. In this study we evaluated the difference response of two aquatic species Chironomus yoshimatisui and Limnodrilus hoffmesteri habiting to changes of discharge due to heavy rains. We compared the differences in their resilience and recover to disturbances. Our results showed that after a heavy rain during the sampling periods, the proportion of macrosubstrate highly increased and was not recovered into the previous states. Nonmetric Multi-dimensional scaling based on Chironomidae and Oligochaeta biota well represented annual and seasonal differences with heavy rain effects. Random forest model showed that the abundance of C. yoshimatisui were mainly influenced by microsubstrate, precipitation and Reynolds number, whereas stream roughness, mesosubstrate and macrosubstrate much more influenced the abundance of L. hoffmesteri.

Benthic macroinvertebrates were collected using the Surber sampler from streams in forest areas in Southern Korea in spring and summer. Self-Organizing Map (SOM) was utilized to reveal community patterns in response to natural and anthropogenic variability in different seasons. The gradient was mainly observed according to degree of pollution and altitude. Subsequently, community compositions reflected seasonality in less-polluted area, showing difference in functional feeding groups. Gatherer-collectors and filterer-collectors were abundantly collected in spring whereas scrapers and predators were sampled in a majority in late summer. Representative species groups were identified in different seasons. persistence in communities in response to natural and anthropogenic variability.

Pomacea canaliculata (golden apple snail) as an invasive species in Asia has become a serious agricultural pest, especially in young rice, and makes significant environmental changes resulting from the depletion of macrophytes in natural wetlands. Even though various environmental factors influence to growth rate, reproduction, survival and behavior in apple snail, water temperature is one of the overwhelming effect on freshwater snails in general. In this sense, the objective of this study was to examine the changes of individual behavior in the apple snail according to the temperature changes. The snails were acclimated at 25℃, and 9 behavior categories were examined in each temperature regime (25℃ to 30℃, 2 5℃ to 20℃, and 25℃ to 15℃) for three days. Autocorrelation function (ACF) was applied to characterize the presence or absence of periodic behaviors in apple snails. The snails’ behavior in the treatment of elevated temperature were irregularly fluctuated or decayed in most behavior categories. On the other hands, in decreasing temperature from 25℃ to 15℃, the snails were nonstationary, especially in clinging behavior. The snails showed periodicity and some of them were decayed in clinging behavior in temperature changing from 25℃ to 20℃.

Due to unprecedented economic development and human aggregation since the end of 20th century, disturbances are ubiquitous across different fields, conservation, pest management, biodiversity, agriculture/forestry, fishery, and epidemics. Disturbing agents are spatially and temporally expanding and regarded difficult to analyze due to complexity residing in the totality of environment-organism relationships. Some basic mathematical models were reviewed in expressing temporal abundance and spatial distribution of populations. Ecological modelling procedure was outlined, and a few case studies were presented in pest population dispersal. Efficiency of spatial models was further illustrated in prediction and provision of management policies. Other related models such as individual based models and cellular automata were discussed additionally in expressing spatial and temporal dynamics in individual and population levels.

An Individual-Based Model (IBM) was developed by employing natural and toxic survival rates of individuals to elucidate the community responses of benthic macroinvertebrates to anthropogenic disturbance in the streams. Experimental models (doseresponse and relative sensitivity) and mathematical models (power law and negative exponential distribution) were applied to determinate the individual survival rates due to acute toxicity in stressful conditions. A power law was additionally used to present the natural survival rate. Life events, covering movement, exposure to contaminants, death and reproduction, were simulated in the IBM at the individual level in small (1 m) and short (1 week) scales to produce species abundance distributions (SADs) at the community level in large (5 km) and long (1~2 years) scales. Consequently, the SADs, such as geometric series, log-series, and log-normal distribution, were accordingly observed at severely (Biological Monitoring Working Party (BMWP⁄10), intermediately (BMWP⁄40) and weakly (BMWP›50) polluted sites. The results from a power law and negative exponential distribution were suitably fitted to the field data across the different levels of pollution, according to the Kolmogorov-Smirnov test. The IBMs incorporating natural and toxic survival rates in individuals were useful for presenting community responses to disturbances and could be utilized as an integrative tool to elucidate community establishment processes in benthic macroinvertebrates in the streams.

Structural property in communities of aquatic insects and benthic macroinvertebrates could reflect the impact of environment on aquatic ecosystems. Benthic macroinvertebrates were collected at 18 different lakes across different levels of environmental impact in Korea. Community responses were analyzed by species abundance distribution (SAD). Rank-abundance (or relative abundance) curves were evaluated by classical SAD (Geometric series, Log-series, and Lognormal distribution) and niche apportionment models (dominance pre-emption, random assortment, random fraction, and dominance decay). Geometric series was more accepted in lakes among classical SAD models. Niche apportionment models were observed in a diverse manner across different level of ecological integrity in lakes. Dominance decay model and random fraction model were frequently fitted to the lakes with higher integrity, while dominance pre-emption and random assortment models tend to be presented in low to middle range in integrity.

Stream and river habitats are characterized by a uni-directional water flow. Organisms colonizing such habitats are faced with the constraint of continuous downstream flow. Some ecologists find it puzzling that upstream is colonized by insect communities although the insects are continuously faced with downstream flow. The obvious solution to the puzzle is that there exist compensatory strategies, three of which have gained some notoriety in recent years: 1) diffusive random movement and density-dependent regulation of population size; 2) daily directed movement during larvae stage; 3) the compensation of larval drift by adult upstream flight. We have adapted an eco-evolutionary individual-based model (IBM) to accommodate typical life events of aquatic insects, such as birth, death, diffusion, and drifting. The probabilities of these events, which occur on the individual level, depend on both biological (e.g., local competition, upstream flight by adult insects) and environmental (e.g., unidirectional flow) constraints. The evolution of selected traits, namely, adapted water velocity, drifting time and distance, and upward flight distance, was investigated through simulation. We find that, while the three strategies are generally able to sustain upstream populations, the exact compensation of drift loss allowed by upstream flight makes the third strategy less “asteful” a population of upstream flight strategists to outcompete diffusive movement strategists. We also report branching of adapted traits in drifting during the course of evolution. Individuals with high current velocity preferences either spend short (several seconds) or long (an hour) duration in water flow, while the individuals with low current-velocity preference only spend middle range (half an hour) of duration in water flow.

In order to achieve the optimized pest control, correct estimation of pest densities is a prerequisite to monitor pest damage and to provide efficient pest management plans. Parameters regarding diffusion (e.g., diffusion constant) and population size (e.g., growth rate) were estimated by using diffusion equation. The time series dispersal data of Whiteflies collected in greenhouse were used for modeling. Cross-correlation analysis was conducted to reveal the range and direction of pest population invasion. Sampling theory was further investigated regarding estimation of densities, and population dynamics of Whiteflies were discussed in two dimensions.

The EAG (Electroantennogram) has been used to find out chemical substance effective to insect. We tried to use EAG recording for catching of responsible acoustic signals to Lirimyza trifolii (Diptera: Agromizidae). In fly auditory organ known as Johnston's organ located on antenna. Pure tone sounds (sine wave) and courtship songs of several kinds of species were broadcasted to excised head of the fly. Significant EAG signals were detected when released the 20 Hz pure tone sound and long pulse train patterns, which were courtship songs of Cryptonevra inquilina and Lipara japonica (Chloropidae). For conformation of it's effectiveness, we further analyzed movement behavior with the signal got from the EAG recording. Information entropy could represent the specimens activities of movement tracks. The entropy with sound was relatively lower than without sound. The combination of EAG responding and behavioral observation would be useful to analyze the response of insect pest against acoustic signals and develop acoustic pest managing tool in agriculture.