The occurrence of sudden strike pest events in urban areas is increasing as global warming intensifies, consequently, re causing harmful impacts. Studies on these incidents are fewer in number and insufficient compared to research on other nuisances such as mosquitoes and flies. Therefore, we conducted a study on the development of a selective collection method, using a filter layer to establish a monitoring system for Ephemera orientalis (Ephemeroptera: Ephemeridae), a species frequently identified as a sudden strike pest. Three sampling points were selected along the Hangang River in Namyangju, where E. orientalis outbreaks occur. Prototypes, consisting of four layers and with a light source attached to attract insects, were installed at each sampling point. Sampling was performed every 30 minutes between 19:00 and 22:30 in the month of June. The filter interval of each layer was adjusted so that the collected mayflies were distributed into specific layers. To evaluate the collection efficiency in line with the materials and the filter intervals, the optimal collection efficiency was investigated by combining two types of layer materials (stainless and acrylic) and filter intervals (1-5 mm). The optimal conditions were as follows: The selective collection efficiency was found to be highest at 96.5% when the interval of the selective target filter was 2.0 mm and there was one upper filter.

We developed a new ecotoxicological test method using native test species, eggs of Ephemera orientalis, and five kinds of industrial wastewater were tested to validate the test method. The water samples were collected in Jun 2006 from the following industries: pesticide, metal plating, PCB, leather1, and leather2. Wastewater and effluent were diluted by distilled water, respectively, to prepare various concentrations, 100, 50, 25, 12.5, 6.3, 3.1, and 0%. For the egg bioassay, 20 freshly laid eggs (<24 h old) were exposed to test solutions in a Petri dish (52×12 mm) at 20℃ with photoperiod of 16 h light and 8 h dark for 14 days. The median egg hatching concentrations (EHC50) were estimated using Probit analysis. All EHC50s of wastewater were less than 3.1%, which meant very high ecotoxicity except for the wastewater of PCB industry having 6.1% of EHC50. Among the effluents, the least toxic effluent was from pesticide industry having 58% of EHC50, while the effluent of leather2 was the most toxic having 7.3% of EHC50.

Field-collected populations of mayflies, Ephemera orientalis were tested for susceptibility to 10 different insecticides using a direct-contact mortality bioassay. Ephemera orientalis subimagoes were susceptible to the insecticides chlorpyrifos, fenitrothion and chlorfenapyr with LD50 values of 69.7, 78.8 and 81.9μg/♀, and adults had LD50 values of 71.9, 78.8 and 85.4μg/♀, respectively. Susceptibility ratios(SRs) of subimagoes and adults of E. orientalis to the 10 insecticides were 1.0 to1.2 folds. The mayflies showed higher susceptibility to organophosphates than to pyrethroids. The SRs of Anopheles sinensis to E. orientalis were 514 to 1,438 fold higher for organophosphates (LD50 values of 0.05 to 0.23μg/♀) and 62 to 1,155 fold higher forpyrethroids (LD50 values of 0.13 to 2.41μg/♀). The SRs of Culex pipiens to E. orientalis were 606 to 3,595 fold higher for organophosphates with LD50 values of 0.02-0.17μg/♀ and 81 to 1,365 fold higher for pyrethroids with LD50 values of 0.11- 1.83μg/♀. These results indicate that the use of ineffective insecticides will result in unsatisfactory control against field populations of the subimagoes and adults of E. orientalis. This work was supported by a research grant from the National Vector Control and Surveillance work performed by the Korean National Institute of Health.

Acetaminophen (CAS 103-90-2) is one of the most used pharmaceuticals around the world. In Korea, it was produced 1,069 tons in 2003. This chemical is not eliminated in wastewater treatment plant and may flow into the ecosystem through various routes. Therefore, there is a possibility that it can make an adverse effect on aquatic organisms. To examine its ecological toxicity, we used three native Korean aquatic invertebrate species, Daphnia sp., Chironomus yoshimatsui, and Ephemera orientalis. The acute toxicity on Daphnia sp. was moderately high, and its 48 hour median immobilization concentration (EC50-immobilization) was 51.7 mg/L. On the other side, the reproductive toxicity was very high, and its EC50 of 25 day reproduction test was 0.005 mg/L. In E. orientalis egg hatching test, the median egg hatching inhibition concentration was 0.199 mg/L. C. yoshimatsui was most tolerant to acetaminophen, in which 48 hour median lethal concentration (LC50) was 400.0 mg/L and 45 day median emergence inhibition concentration (EC50-emergence) was 45.27 mg/L. From this results, we concluded that acetaminophen is hazardous to freshwater macroinvertebrates, especially to water flea. Therefore we need to study more about pharmaceuticals' ecotoxicology including acetaminophen and to assess their potential ecological risk.

We determined the complete mitogenome of the oriental mayfly, Ephemera orientalis (Ephemeroptera: Ephemeridae) and the dragonfly Davidius lunatus (Odonata: Gomphidae). The 16,463-bp long E. orientalis and the 15,912 bp long D. lunatus mitogenome contains gene arrangement and content identical to the most common type found in a diverse insect order. Most individual E. orientalis and D. lunatus mt genes were well within the size found in the respective genes of other insects. The initiation codon for the D. lunatus COI gene was typical as ATA, whereas no typical start codon was found in the start region of E. orientalis COI gene. The A+T-rich regions of both mitogenomes have a few unusual feature. The A+T-rich region of E. orientalis contains a tandem repeat composed of two identical copies of 55 bp long, whereas that of D. lunatus contains a tandem repeat composed of duplicated identical 261-bp copies and one partial copy of the repeat. Also, the A+T-rich region of E. orientalis contains a single sequence and that of D. lunatus contains nine sequences, along with the tandem triplicate sequences, that has the potential to form stem-and-loop structures, flanked by the conserved sequences, “TA(A)TA” at the 5’ end and “G(A)nT’ at the 3’ end. Furthermore, the A+T-rich region of D. lunatus contains two tRNA-like structures, tRNALeu(UUR)-like sequence and tRNATyr-like sequence that have proper anticodon TAA and clover-leaf structure that were previously found in the hymenopteran insects.

Traditionally oxygen demands and concentrations of variable pollutant have been used for the assessment of lentic or lotic water quality. But there is a high probability that newly synthesized chemicals flow into the aquatic ecosystem, and it is very hard to investigate that many kinds of chemicals interact even though they exit at lower level than legal standards. As a consequence of limitation of chemical assessment for media, biological assessment techniques for accepters which are affected by pollutants or physicochemical properties have been developed. However, it still has several weak points because it does not have the ecological relevances using the internationally standard test species which do not inhabit Korea. Besides, the assessment using just one or two species may have a possibility of overestimation or underestimation because a certain species can be extremely sensitive or insensitive to a certain chemical or physicochemical property. Therefore, we used four kinds of indigenous aquatic invertebrates to assess the local stream quality and integrated their responses into a new index which ranges from 0(bad) to 1(good). We assessed four streams throughout Ansan and one stream in Gapyeong, and index values of two streams near residential and industrial area in Ansan were under 0.9 and the others were over 0.9.