1. Introduction
The range of altitudes of Wuling area in Sheipa National Park is from 1740 to 2500 meters above sea level. The research team started investigating the riparian insect community at the mountain river Chi Chia Wan Stream of Wuling area since 2004; at 2011, there are a total number of 24 orders 190 families and 177,887 individuals of insects collected in this area. After identification and analysis, the results showed that Diptera is the most dominant group of insects with the most amounts; its sum is 51 families 100,018 individuals which is 56.23% of the total number [1] . In 2012, besides the continuous investigation in the WLTER common sites, we have also conducted an investigation specifically on the blood feeding Culicoides spp. (Diptera: Ceratopogonidae) based on two separated reports of midge attack incidents, one of which was reported by one of the team members in 2010 at the #3 Dam II station (Figure 1) of Chi Chia Wan Stream and the other one was by tourists in 2011 near Chaofeng bridge.
Chen [2] has recorded 60 species of Culicoides spp. originated in Taiwan, both inland and offshore islands such as Penghu Islands, Orchid Island, Green Island, and Hsiao Liuqiu Island, etc. According to the collection records from Taiwan, Culicoides spp. are mainly bloodsucking on livestock and there are very few reports that sucking on human. Furthermore, Culicoides spp. are the main vector for the bovine ephemeral fever which prevails in spring (March, and April) and in fall (September and October)each year around the cattle range [3] . The most typical case is C. arakawae served as vector for the leucocytozoonosis [4] . However, in China there are C. pulicaris that feed on human blood; in South
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Figure 1. The investigation stations are at WLTER in Wuling area, Sheipar National Park.
Pacific there are records of C. belkini biting human [5] . C. grahamii in Africa and C. austeni in South America are vectors of Acanthocheilonemaperstans. C. grahamii is also vector for Mansonella streptocerca. And C. urens in South America is vector for Mansonella ozzardi [6] .
2. Materials and Methods
The original long term ecological research in Wuling area is a bimonthly investigation, from 7:30 to 19:30, we set up and retreat multiple ecological collecting traps [7] from the eight locations along Chi Chia Wan Stream (Figure 1). The catchment located at Wuling area, Sheipar National Park, central Taiwan. The annual precipitation is 1642 mm in average, the dry season with mean monthly rainfall less than 40 mm (October to next February), and frequently exceeding 300 mm during the wet season (May to September). The longitude and latitude of the study area is situated at 24˚23'N, 121˚18'E and denoted both in Figure 1 and in the text as well according to our previous work [8] .
For this investigation which dated from January to December of 2012, we added human bait method during the day time, trapping Culicoides for 10 minutes each time on each of the eight locations: station #2, #3 #4, #12 and #13, #8, #5 and #9 (Figure 1). Detail situation of each station is noted as our previous paper about the prey of Taiwan Landlocked Salmon [9] . On the other hand, we also used light trap method on three of the locations only: #12, #13 and #5, to set the light trap for collecting Culicoides from 16:00 to 22:00. Although restricted by power supply, we managed to extend the power chords and set up trapping lights on the trees as close to the waterside of Chi Chia Wan Stream as possible. All the samples we collected are preserved in 75% alcohol and brought back to the lab to examine under microscope. The individual number counted after identification and basic analysis for comparing the difference of the number changed during the investigation period. The identification of the genus Culicoides based on the previous works Chen [2] and Yu [10] .
3. Results
The result of human bait method at all eight locations in Wuling area is zero, while all three locations using light trap method have collected a total of 13,191 individuals of in April, June, August and October. Of the three locations, we have collected the most Culicoides in #13, a total of 7337; in #5 we collected the least, only 1715 individuals (Table 1).
The monthly collection of Culicoides was the highest in June, and the total number of all three stations was 6606, but not in February and December. The highest amount of Culicoides collection in single station in single month was found at #13 in June, the total number is 5723 (Figure 2).
4. Discussion
This study started investigating the insect community at the mountain river Chi Chia Wan Stream of Wuling area since 2004, based on the long term ecological monitoring project of Sheipar National Park. It is the issue of land locked salmon conservation and preservation in Taiwan. Some cases of Culicoides attacked park ranger and tourist happened in 2010 and 2011. The study applied the human baiting trap to investigate the population at 2012 for one year.
Comparing to the Forcipomyia taiwana and other Ceratopogonidae midges, Culicoides is obviously larger in size. In addition, the wing stigmata are a significant diagnostic character for identifying the Culicoides midges from others. According to Capinera [11] the Culicoides prefers to lay eggs in moisture soil and larvae are aquatic or semi-aquatic. All the investigation station along with the
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Figure 2. The insect numbers of Culicoides sp. bimonthly collected by light traps on three stations (#12, 13, 5) of Wuling area in 2012.
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Table 1. The Culicoides adult attracted by human bait method and light trap method at the stations of Wuling area in 2012.
-: uncheck.
river as riparian habitat [7] just meet the environmental quality for Culicoides. The swarmed Culicoides attacked our team member in 2010. It was not happened until the time during 17:00-18:00 at the #3Dam II station. So, that is the reason why we decided to investigate after sunset. It is the active time period for the Culicoides midges. Based on Chiu [3] a study from the animal farm, the majority of active time periods are dusk and dawn; it is not common as whole day active. And we only think about the time period after sunset because of the reason that we have to compare with light trap at a time.
Among 8 stations insect collected a total of 13,191 individuals of in April, June, August and October. But there is no insect collected in both February and December. It may be because of the low temperature in the 1800 m high mountain. Of the three locations, we have collected the most Culicoides in #13, a total of 7337; in #5 we collected the least, only 1715 individuals by light trap (Table 1). It is to say the Culicoides occurred in Wuling is true. And the population obviously increases from April to June at station #3. However, the population sudden decreased in August besides of that in # 5. It may be caused by the typhoon SAOLA (no. 1209) attacked Taiwan from July 31st to August 3rd. The typhoon SAOLA made soil, mud, rock and fallen tree or log altogether flashed down by the flooding conducted by 1200 mm super heavy precipitation. And the result caused the river bed land scape changed and a lot of massive reformed of the riparian ecological system. The habitat of Culicoides also changed naturally in this situation. Until October, the changed landscape making some small water bodies preserved some larvae of Culicoides.
As it is just revealed by the above collected insect by light trap that the Culicoides midges actually existed in Wuling area. However, there is no more biting record in the area after 2012. The interpretation to these cases pointed to 1. The investigating time point may be not exactly after sunset, but still cove the time period of the major active time period. So, that the Culicoides midges completely absent by the human bait method is unusual situation. 2. The population decreased and disappeared caused by the flooding and the riparian landscape changed. The potential habitat removed may be the key factor of the population perished. 3. According to the reference articles, Culicoides midges preferred more to suck the blood of wild animals than to that of human [12] . It is worth to note about the Culicoides not sucking human blood. After all, the study undergoes in Sheipar National Park where the wild animal conservation is better than other place. And there is no Culicoides midge attracted by human bait method.
Acknowledgements
We would like to present our appreciation to whom has helped in the investigation project. They are Hsing Hau Wang, and Ya Yuan Wang. The financial support by the project no. PG 10012-0330 is also appreciated.