Chironomid fauna Piptera: Chironomidae) in the Hosomidani valley, western Chugoku Mountains, Japan

The Hosomidani riparian fbrest, located around the origin of the Ohta River basin, is one of the most nature-rich districts in Japan. We investigated chironomid fauna in the Hosomidani valley as　anindicator taxon to evaluate the species diversity of　&eshwater benthic macroinvertebrates. On 23 August and 2 November, 2005, ironomid lalvae were collected in the main stream of the Hosomidani River, small streamletsflowing Into the main stream and the floodplain marsh along the Hosomidani River,and were reared to adults in the laboratory to identify species. A total of 52 species was collected and of which 17 Were newly recorded in the Ohta River basin Thirty-five species were collected in the main stream and of which 14 were also fblmd in the streamiets. On the other hand, 12 out of 16 species collected inthefloodplain marshes were not found in the main streamand streamiets, Polypedilum (Trliodura) caudocula was only found in the noodplain and this is the second record next tothe descnptlOn Of this species in 1991 ･ These results indicate thaHhe high species diversity of cbironomids in tile Hosomidani valley is supported by the presence of the noodplain,Article信州大学山地水環境教育研究センター研究報告 6: 103-108(2010)departmental bulletin pape

Benthic macroinvertebrates in the Nishina Three Lakes and Lake Nojiri, highland lakes in Japan

order to clarifythe current status of the benthic communities in the Nishina Three Lakes (Lakes Aoki, Nakatsuna and Kizaki) and Lake Nojiri, highland lakes located atthefoot of the Japanese Northem Alps in Nagano Prefecture, We collected benthic macroinvertebrates on 1 and 2 August, 2007, Chironomidaeand Oligochaeta were the major CrOinvertebrates at all study sites and the taxonomic composition of Chironomidae was differentamong the sites. Sergentia was collected in Lakes Aoki andKizaki, whereas Chironomus was collected in all the lakes except Lake Aoki. Chaoboridae was collected at the center of the Lakes Nakatsunaand Kizaki but not in Lakes Aoki and Nojiri. The comparison of the densities of benthic maroinvertebrates with the previous studies suggests that the densities of Oligochaeta increased in Lakes Aoki,Kizakiand Nojiri, and Chironomus increasedinLake Nojiriin recent decades.Article信州大学山地水環境教育研究センター研究報告 6: 95-102(2010)departmental bulletin pape

Distribution of benthic insects in a riffle/pool section of the middle reaches of the Shinano River, Japan, with emphasis on Trichoptera

We investigated the density and taxonomic composition of benthic insects in a 300 m section of riffle / pool habitat in the Shinano River, Japan. The most abundant taxa were Chironomidae, followed by Trichoptera. The total density of caddisflies and their contribution to the total density of benthic insects ranged from 56 to 21,744 (mean 11,644) ind. m-2 and from 2.6 to 44.6 (mean 29.4) %, respectively. We conducted a canonical correspondence analysis using current velocity, depth, and the ash-free dry mass of epilithon as the main factors. Benthic insect assemblages were significantly associated with the longitudinal gradient of the riffle/ pool structure. Stenopsyche marmorata and hydropsychid species were abundant in the riffles whereas Psychomyia acutipennis were abundant in the pools.Article環動昆.22(1):17-22(2011)journal articl

Adult caddisfly (Trichoptera) attached to artificial lights in the middle reaches of the Shinano River from 2005 to 2007

The species composition and abundance of adult caddisflies attracted to the illuminated showcase of a vending machine set along the middle reaches of the Shinano River were investigated every Sunday night from April to November in 2005 to 2007. A total of 1,405 adult caddisflies was collected during the investigation periods. We identified a total of 13 species belonging to 11 genera of 8 families. The most abundant species was Psychomyia acutipennis (Ulmer 1908) each year. Psychomyia acutipennis adults were collected from mid-May to the beginning of October (the range of mean air temperature was 13.8 to 27.7°C), with its seasonal abundance divided into several peaks, i.e., the end of May, the beginning of June, and the end of August to the beginning of September in both 2006 and 2007. On the other hand, in 2005 when there was no large-scale summer flood and there were no marked abundance peaks. The present study suggests that the mean air temperature and summer floods impacted the seasonal abundance of P. acutipennis adults.ArticleZoosymposia. 5(1):143-146 (2011)journal articl

Emergencetime and period of chironomid midges occurrlng from an indoor drainage

Mass emergence ofchironomidmidges often leads to severe nuisance conditions in food industries. We tried to clarifythe seasonal abundance and the emergence time of chironomids caught by a light traps in this industry. A total of38,708 chironomids was collected duringthe study period, andthe largest number of adult was recorded in fall. In addition, some chironomids were collected even in thewinter. These results suggest that air temperate in winter at this industry is highenough for emergence of chironomids.Asfbr emergence time,the number of chironomids increased around dawn and dusk,and decreased in the day and night. The results of the present study would be useful information for drafting planto prevent outbreaks of nuisancemidges from indoor sewage drain.Article信州大学山地水環境教育研究センター研究報告 6: 109-114(2010)departmental bulletin pape

Silk protein of the larval caddisfly, Sienopsyche marmorata (trichoptera: stenopsychidae)(trichoptera: stenopsychidae)

Stenopsyche marmorata is one of the common caddisfly species inrivers and streamsin Japan which is distributed in East Palaearctic Region･ The larvae spin Silk fiber between stones on the bottom of Bowing water, the silk proteinofS･ marmorata would be one of the best sources of natural biopolymersthat could be used as materials for aquatic industrial purposes･ In order to analyze the basic characteristics towards further applications, we measured physical properties, thermal behaviorsand molecular confわrmation of the silk protein of larval S marmorata･ The wet weight of the larval body andthe silkgland of SOrata Were 543･5土5419and 44･7土17･9 mg, respectively, The water content of the liquid silk protein in the silkglands of the living larvae was 73.4土2.2%. The elongation atthe breaking point of the solid silk proteingland in dry state was 2･2%, whilethat of sampleinwet state was･ 6012%, suggestlngthe silk protein glands become soft and stretchable in wet conditions. FT-IR spectra of the silk protein film showed a major absorption band at 1650 cm-1 (Amide I band), which is attributed to the random coil molecular conformation. The silk fiber showed a major endothemiCpeak at 32loC onthe differential scanning calorimetry (DSC) curve, which position is slightly higher than the endothemic peak for the silk film, Suggesting an increaseinthe thermal stabilityfbr the silk fiber from caddisfly,Article信州大学山地水環境教育研究センター研究報告 6: 1-8(2010)departmental bulletin pape

Prediction of emergence period of overwintering Chironomid larvae (Diptera: Chironomidae) at lower reaches of the Kiso River, Central Japan.

Species composition and period of emergence were investigated for overwintering Chironomidae at the lower reaches of the Kiso River by rearing larvae to obtain fundamental information for drafting a plan to prevent outbreaks of nuisance midges. Adults of 9 species emerged from the substrate samples in February 2006. The four most abundant species, Stictochironomus akizukii, Hydrobaenus kondoi, Tanytarsus takahashii and Einfeldia dissidens, occupied 88.0% of the total abundance. Using effective accumulative temperature for emergence and in situ water temperatures, the in situ emergence periods of the overwintering generation in 2006 were predicted as until early March for H. kondoi, from the end of March to early May for S. akizukii and T. takahashii, and late April to mid-June for E. dissidens.Article衛生動物.58(3):183-190(2007)journal articl

Changes in the species composition and density of caddisflies (Trichoptera) after an excavation work in the middle reaches of the Shinano River, Japan

We evaluated the effect of riverbed excavation on the macroinvertebrate community in the middle reaches of the Shinano River, Japan. Macroinvertebrate samples were collected at a treatment site, created by excavation of the riverbed, over a 98 d period. We compared the density and diversity of caddisfly larvae collected at the treatment site to a control site, located upriver. Three of 10 species found at the control site were not found at the treatment site. Furthermore, the Shannon-Wiener species diversity index (H') was lower at treatment site, although the total caddisfly density was similar to the control site by Day 98. The three most abundant species at control site were Psychomyia acutipennis, Potamyia chinensis, and Hydropsyche orientalis. The density of all three species was initially low at the treatment site following the excavation (Day 1). Beginning at Day 69, the density of Ps. acutipennis began to increase at the treatment site and was more than twice as high as at the control site by Day 98. Similarly, the density of Po. chinensis increased between Day 59 and 98 but did not exceed the density at the control site. In contrast, H. orientalis was rarely observed at the treatment site. Our results suggest that large-scale removal of the riverbed affected several key physical parameters and changed the density and species diversity of the trichopteran community.Article環動昆.20(1):17-26(2009)journal articl

Downstream drift of suspended matter and benthic macroinvertebrates swept by a riverbed leveling work in the middle reaches of the Shinano River, Japan

The amounts of suspended matter and benthic macroinverbrates swept by an experimental riverbed leveling work were investigated in the middle reaches of the Shinano River. The concentration of suspended solid (SS) was 8.43 mg/L at the four study sites on the day before the beginning of the riverbed leveling (Day -1), but it increased up to 115.53 mg/L at the site 200 m downstream from the working site (St. 2) on the day of the beginning of the work (Day 0). Ash-free dry mass of the SS showed that inorganic matter content accounted for 84.4% of the SS at St. 2 on Day 0 and was much higher than Day -1 (72.9%). The most abundant particle size class of SS at St. 2 on Day 0 was 1-75 μm, followed by ＜1 μm, and inorganic particles of 1-75μm size class were the most abundant component swept by the leveling work. Down stream drift of benthic macroinvertebrates was mainly composed of Chironomidae, Oligochaeta, Ephemeroptera and Trichoptera at the study sites both on the Days -1 and 0. The drift densities of Oligochaeta and Chironomidae were 0.15 and 0.54 ind./㎥ at St. 2 on Day-1, but on Day 0, they increased up to 143.0 and 45.9 ind./㎥, respectively. The benthic macroinvertebrates swept by the riverbed leveling work were suggested to be flown away at least 1 km downstream from the working site.Article環動昆.22(1):11-16(2011)journal articl