This study was conducted aiming to figure out two things. First, knowledge of the change in spatial distribution of Tetranychus urticae depending on how to control it (using pesticide or natural enemy). Second, spatial association of T. urticae and Phytoseiulus persimilis in biocontrol plot (B.P). The data was analyzed by spatial analysis by distance indices (SADIE) using global aggregation index, Ia . Ia values were 0.77-1.37 in conventional plot (C.P) and 0.88-1.68 in B.P, respectively. However, the fluctuation level of Ia in B.P was higher than C.P. Therefore, the results indicated that there was a clear spatial pattern change in B.P, i.e. prey’s spatial distribution is affected by natural enemy. And spatial association analysis showed that T. urticae and P. persimilis have positively associated. It means that T. urticae is relatively low mobile prey, and P. persimilis is relatively high mobile predator.

Dynamics of predator-prey systems are strongly affected by the strategic behavior of both predator and prey. Thus, understanding the relationship between the strategic behavior and the species survival is necessary to comprehend the system resilience and stability. In the present study, we constructed a spatially explicit lattice model to simulate integrative predator (wolf)-prey (two rabbit species)-plant relationships. Wolves have only the hunting strategy, while rabbits have the hunting-escaping strategy. When a rabbit simultaneously encounters its predator (wolves) and prey (plant), either hunting or escaping should take priority. Hunting priority is referred to as hunting preferred strategy (HPS), while escape priority is referred to as escape preferred strategy (EPS). These strategies are associated with some degree of willingness to either hunt (H) or escape (E). One rabbit species takes HPS (HPS-rabbit) and the other rabbit species takes EPS (EPS-rabbit). We investigated the changes in predicted population density for wolves, rabbits, and plant with changes in the value of H and E. Simulation results indicated that EPS-rabbit had a greater chance for survival than HPS-rabbit regardless of the initial density of EPS-rabbit, and the chance was optimized at the appropriate values of E and H. In addition, we briefly discussed the development of our model as a tool for understanding behavioral strategies in specific predatorprey interactions.

Understanding the predator-prey dynamics is essential to comprehend the ecosystem resilience and stability because ecosystems consist of dynamically interacting subsystems with predator-prey relationship. The relationship is likely to be of the predator and prey hunting-escaping strategy. Thus, to better understand the ecosystems, we should comprehend how the hunting and the escaping strategy affect the ecosystems. To do so, we constructed a spatially explicit lattice model to simulate the integrative predator-prey-plant relationships. When an individual simultaneously encounters its predator and/or prey, the individual should take priority between the two strategies. When the hunting (or escaping) strategy takes priority, we call it hunting preferred strategy, HPS, (or escaping preferred strategy, EPS). Each strategy was characterized by the willingness for each strategy. The degree of willingness was represented as H (for hunting) and E (for escaping). Higher value of H (or E) means stronger willingness for hunting (or escaping). We investigated the population density of each species for different values of H and E for HPS and EPS. The main conclusion that emerges from this study was that HPS plays a positive role in the ecosystem stability. In addition, we briefly discussed the development of the present model to be used to understand the predator-prey interaction in specific species.

This study was carried out to investigate the status of spot damage by fruit piercing pests and the kinds of these pests on yuzu (Citrus junos) fruit in Koheung, the most chief producing district of yuzu fruit in Korea, from ’97 to ’99. The extent of spot damage by fruit piercing pests on yuzu was increasing in recent years. This damage of fruits was severe in the lower canopy than the high one from ground and intercropping groves between yuzu trees had a greater damage to compare with single cropping of yuzu. Spot damage of yuzu fruit was occurred mainly from late September to early November when yuzu fruit is enlarging and coloring yellow. The blackish concave spot on yuzu fruit surface was appeared in 3 days after introduction of Riptortus clavatus into a netted cage containing one yuzu fruit and the diameters of this spot was 8.3 mm. At 10 days after introduction, this spot changed into milky-white with 9.2 mm diameters. One concave spot has contained oil cells by 17.7 and its external appearances has unchanged until harvest. The kinds of piercing pests of yuzu fruit were investigated with 3 orders, 16 families and 37 species. These pests were classified by 11 species of bugs, 5 species of hoppers and 21 species of moths. Among them, dominant species were Physopelta gutta, Halyamorpha halys, Empoasca vitis, Aedia leucomelas, Agrotis tokionis, etc. Macroglossum bombylans and Acherontia s쇼x are newly confirmed species as the fruit piercing moths in Korea.