A new collembolan species (Paranura rosea) which was native to Korea was selected for evaluating the effect of temperature on their biology. Development, and reproduction of P. rosea were investigated at 15, 20, 25 and 30℃ Hatchability of egg was not affected by experimental temperature, and the lower threshold temperature for development of P. rosea was estimated to be 7.53℃. The temperature reduced the juvenile and adult (maturity period). The intrinsic rate of natural increase and finite rate of increase per week at 20℃ which are maximum values showed significant difference with other experimental temperatures. Survival rate, cumulative reproduction and head capsule width was fitted by several models. Especially, the model which fitted for estimating head capsule width was used to determine their life stage. Estimated head capsule width of P. rosea at the initial oviposition varied with temperature from 0.36 ± 0.007 to 0.45 ± 0.007 with maximum at 20℃ and minimum at 30℃, and significant difference was observed at all the experimental temperature (P<0.05). However, estimated head capsule width at the last oviposition showed different statistically result at only 30℃. Molting frequency per week of one P. rosea was increased as the temperature increased. Based on this study, temperature greatly influenced on their life stage and reproduction. Therefore, relationship between temperature and P. rosea is very important for understanding their biology.

In Korea very few studies have been conducted in relation to collembola sensitivity to pollutants in populations exposed to soil contaminants in particular heavy metals. The objective of the current research were to study the thermal effects of selected heavy metals on the survival and reproduction of P. rosea in order to assess its applicability as a test species. Petri dishes (87 mm diameter, 15 mm height) were used for compact soil toxicity test and were filled to a depth of 0.5 mm with 6 g artificial soil and 3.5 mL distilled water was added. 20 adults (6 weeks from egg stage) were introduced to each petri dish and placed in two incubators set at 20℃ and 25℃, respectively under continuous darkness. The 28 days EC50s for cadmium in compact soil at 20℃ and 25℃ were 48.9031 and 91.3585 mg/kg, respectively. This thermal toxicity test of P. rosea is advantageous for various environmental sudies, such as toxicity tests.

In this study, egg hatching and larval development of Paranura rosea were experimented at different temperature conditions. The development was studied at four different temperatures, ranging from 15 to 30℃ (in 5℃ intervals), under a dark. As a result, the egg hatching time decreased from 21.67±1.99 to 6.57±1.96 days as the temperature increased from 15 to 30℃. The highest egg hatching rate was 49.27±20.69% at 25℃, where as the lowest rate was 27.97±23.06% at 15℃. The developmental rate increased gradually with temperatures from 15 to 30℃, and the developmental rate was highest at 30℃. The survival rate was highest at 15℃ (85.27 %) and lowest at 30℃ (57.53 %). This wide thermal adaptation in egg hatching and larval development of Paranura rosea is advantageous for various environmental sudies, such as toxicity tests.

In soil ecosystems, chemicals are often found as mixtures. Therefore, the toxicity data generated by single toxicity tests are inadequate for assessing the potential risk of complex mixtures of chemicals for soil ecosystems. In the present study, the mixture toxicity of copper and manganese on the reproduction of Paronychiurus kimi were assessed using a Toxic Unit approach (1TU=EC50). The concentrations of each metal in the mixture were summed as follows: TUmixture = CCu/EC50 of Cu + CMn/EC50 of Mn, where CMetal are the concentrations of copper and manganese in the mixture. From the Sum TU based dose-response relationships, sum of a toxicunit (TU50) at 50% reduction for the mixture (EC50mix) was calculated. The binary mixture toxicity was defined as being concentration additiv (EC50mix=1TU) or as being more or less than additive (EC50mix<1TU or 1>TU, respectively). Also, values of the mixture (TUi) at i% reduction found were predicted to get more insight regarding the relationship between mixture toxicity and various effect levels (ranging from EC10 to EC90). The toxicities of copper and manganese mixtures were less than additive at the EC10 level, whereas more than additive at the EC90 level. These findings imply that the effect levels are important for determining the toxicity of metal mixtures.

Determining age distributions of insect is required for many basic ecological studies. Most of insect developmental studies, the head capsule width and other developmental traits have been widely used to distinguish the instars. Unlike to other insect species, collembolan continues to molt after they reach sexual maturity. So these traits sometimes make it difficult to conduct developmental studies. Model animal used in this study was Paranura rosea a native collembolan speciese. To determine the age groups of P. rosea, we periodically (1week) made digital images of P. rosea (over 100 different images) under the magnifier (DIMIS-M) for consecutive 20 week. And then the head capsule width and the surface area of P. rosea were analyzed using a image software (ImageJ). In this test the head capsule widths and surface area were set as developmental parameters. Both two developmental parameters showed time-dependent increase patterns. And they gave good agreements between predicted developmental parameters and observed parameters (r2=0.83 and 0.71). Based on the reproducibility of juveniles and statistical mean separation tests (tukey's test), both two developmental parameters could be divided into 3 age groups. The information given this study will be used as a basis for understanding the population dynamics and other ecological research.

As a fundamental study for chronic test (definitive test), the range finding test must have been done prior to conducting chronic test. The aims of this study were 1) to search the effective concentration range of two different heavy metals (cadmium and nickel) to indigenous collembolan species (Paranura rosea) 2) to compare the toxicity of cadmium and nickel depending on exposure durations. Toxicity tests were conducted in accordance with the standardized toxicity test proposed by OECD. In this study, there were no mortality occurred at all test concentrations for 7-days exposure. In contrast to 7-days exposure, there were slight increases in mortalities were observed at the concentration higher than 400 mg/kg for both heavy metals for 14-days exposure. The estimated LC50s for cadmium and nickel were 3980.65 (2036.08-64668.61) and 1597.85 (1087.87-3817.61) mg/kg, respectively. The results of this study may be used as a fundamental toxicity data for two heavy metals to proceed in chronic test in the future study.