Macroinvertebrate drift in a Rocky Mountain stream

An extensive series of drift collections from a Rocky Mountain stream was used to investigate quantitative patterns in the taxonomic composition of drift throughout spring, summer and fall for 1975–1978. Drift was estimated by drift rate, the number of organisms drifting past a point per 24 h; and by drift density, the numbers of organisms collected per 100 m³ of water sampled.Drift densities were up to ten times greater by night than by day, and 24 h drift densities for the total fauna approached 2000 per 100 m³ in June–July, declining to <500 by autumn. Ephemeroptera, and especially Baetis, dominated the drift. Drift rates were greatest in late spring, around 10⁶ per 24 h, which are among the highest values reported for small trout streams. Drift rates declined to <10⁵ during the summer, and shifts in the taxonomic composition are described.Multiple regression analysis of the relationship between drift rate and density, and the independent variables discharge, benthic density and temperature, showed that discharge typically was a significant predictor of 24 h drift rate, usually the best single predictor. In contrast, 24 h drift density most frequently was independent of discharge, indicating that this measure tends to correct for seasonal variation in discharge, as suggested in the literature. However, this was not invariably true. Drift density significantly correlated with benthic density in five of eight taxa inspected, thus seasonal declines in the benthos probably accounted for parallel declines in drift density.     

Comparison of sensory structures on the antenna of different species of Philopotamidae (Insecta: Trichoptera)

Structure and distribution of sensilla were studied in sixteen species of the caddisfly family Philopotamidae. Their antennae bear numerous curved trichoid and pseudoplacoid sensilla and fewer coronal, styloconic and chaetoid sensilla on the flagellar segments. The most numerous pseudoplacoid sensilla have non-specific localization. The curved trichoid sensilla form clusters ventrally on each antennal segment. Sensilla belonging to coronal, styloconic and chaetoid types have specific positions. Long grooved trichoid sensilla are located nonspecifically in all the studied species. The average number of sensilla per segment decreases from the proximal to distal part of the flagellum. Scapus and pedicellum are devoid of most types of sensilla, however, they bear the Böhm bristles and long trichoid sensilla. A positive correlation between antenna dimensions and its cuticular structures is found.     

Larva,pupa and adult male of Atopsyche (Atopsyche) maxi,a new species from northwestern Argentina and southern Bolivia (Trichoptera: Hydrobiosidae)

Rhagovelia pediformis sp. n. is described from western Colombia and placed in the R. elegans group.     

中国缺叉多距石蛾属六新种记述(毛翅目,多距石蛾科)

研究了中国毛翅目多距石蛾科缺叉多距石蛾属种类,并报道了其中亲缘关系较近的6新种,即端截缺叉多距石蛾Polyplectropus truncatufus sp.nov.,端突缺叉多距石蛾Polyplectropus convexus sp.nov.,斧端缺叉多距石蛾Polyplectropus dolabriformis sp.nov.,颚状缺叉多距石蛾Polyplectropus mandibuliformis sp.nov.,距枝缺叉多距石蛾Polyptectropus rectangulus sp.nov.,喙端缺叉多距石蛾Polyplectropus rostriformis sp.nov..新种模式标本保存在南京农业大学昆虫标本馆.     

A laboratory study on the thermal tolerance of four southeastern stream insect species (Trichoptera,Ephemeroptera)

The acute thermal tolerances of four southeastern stream insect species, Ephemerella invaria (Walker), Stenonema ithaca (Clemens and Leonard), Symphitopsyche morosa (Hagun), and Brachycentrus lateralis (Say) were determined using an artificial stream enclosure. All species were acclimated at 10°C for 72 hours prior to instantaneous immersion into heated water for 96 hours. Percent mortality was recorded and the temperature at which 50% mortality occurred determined (LT5o). Data were subjected to standard statistical analysis.Thermal tolerance values were compared between species tested and to results from previous investigations using similar methodologies. The evolution and life histories of these species were also discussed in relation to their thermal tolerance values.     

Studies on silk secretion in the trichoptera (F. Limnephilidae)

Summary The ultrastructure and amino acid composition of the secreted silk of two species of trichopteran larvae, Pycnopsyche guttifer (Walk.) and Neophylax concinnus McL., were investigated. The spinnerets of these two animals were also examined by scanning electron microscopy. The silk consists of double-stranded, flat ribbons (1–4 wide), composed of bundles of 15–25 Å filaments. There are two components of the silk: the fiber proper and a surrounding coat thought to be a silk gum. Only the outer coat is positive to the EM PATP technique of Thiery (1967), which indicated the presence of neutral sugars. Amino acid analyses of Pycnopsyche silk show that, like other silks, two predominant amino acids are glycine and serine. Arginine, unexpectedly, is the third most abundant and there are a large number of basic and long side-chain amino acids. X-ray diffraction studies of the silk indicate that it has a less crystalline, more amorphous structure than that of other silks.Submitted to the Department of Biological Sciences of the State University of New York at Albany in partial fulfillment of the requirements for the degree of Doctor of Philosophy Acknowledgements. This study was supported in part by a National Institutes of Health Graduate Student Traineeship grant # GM-02014. The author would like to express sincere gratitude to Dr. Stephen Brown for his encouragement and help during the course of this study. I would also like to thank Dr. Curtis Hemenway and Mr. Douglas Halgren of Dudley Observatory for the use of their scanning electron microscope as well as Dr. Helen Ghiradella and Mr. William Radigan for help with the scanning electron microscopy. I owe special appreciation to Dr. Y. Myer of the Chemistry Department of SUNYA for doing an amino acid analysis of the silk and to Dr. K.M. Rudall of the University of Leeds for doing the X-ray diffraction studies of the silk samples     

Flow- and substratum-mediated movement by a stream insect

1. In streams subject to frequent hydrologic disturbance, the ability of benthic invertebrates to disperse within the channel is key to understanding the mechanisms of flow refugium use and population persistence. This study focuses on crawling invertebrates, the effects on movement of abiotic factors (specifically, flow near the stream bed and bed micro‐topography) and the consequences for dispersal. 2. In a large flume, we observed individual cased caddisflies, Potamophylax latipennis, moving in fully turbulent flows over a precise replica of a water‐worked surface. From maps of movement paths, we quantified crawling behaviour and entrainment, and the influence of bed micro‐topography. We manipulated discharge and tested its effect on movement, linear displacement and areal dispersal. The highest discharge treatment was a disturbance to the caddis; the lowest discharge was not. Crawling behaviours were used to parameterise random walk models and estimate population dispersal, and to test the effects of abiotic factors on movement. 3. Bed micro‐topography influenced crawling in several ways. Caddis spent most of their time at the junctions between proud particles and the adjacent plane bed. The frequency distribution of turn angles was bimodal, with modal values approximating the angle required to travel around median‐sized particles. Larvae generally crawled downstream, but crawling direction relative to the flow was skewed by bed micro‐topography and was not directly downstream, unlike drift. 4. Caddis crawled for most of the time and discharge affected almost every aspect of their movement. As discharge increased, caddis crawled less often, more slowly and over shorter distances; they also became entrained more frequently and over greater distances. With increased discharge, caddis spent proportionately less time at the junctions between proud particles and the adjacent plane bed, and more time on the tops and sides of proud clasts. This is curious as most entrainment occurred from the tops and sides of clasts and entrainment is generally considered to be disadvantageous during disturbances. 5. Linear displacement (drift and entrainment combined) was downstream, but the relation between total displacement and discharge was complex. Total displacement decreased at intermediate discharge as crawling decreased, but increased at high discharge as entrainment and drift played a greater role in movement. 6. Within‐stream dispersal via crawling contained elements of both a correlated random walk (we observed directional persistence in turn angles) and a biased random walk (we observed downstream bias in move direction angles) and was best described as a biased correlated random walk. Dispersal was inversely related to discharge, suggesting that the ability of P. latipennis to crawl into flow refugia on the streambed is reduced at high flow.     

毛翅目化石研究进展

本文详细总结和回顾了世界毛翅目化石研究简史,列出已发表的化石种类名录、分布及年代,共37科、193属、661种(包括中国发现的4科9属15种),描述了不同地质时期主要毛翅目化石的分类单元和分布地区。简要介绍了毛翅目分类系统及系统发育、不同地质时期毛翅目化石的产地及时代。初步分析了目前该类群所存在的一些问题,并对今后的研究工作进行了展望。     

Feeding habits and food resources of filter-feeding Trichoptera in a regulated mountain stream

A year-round study was conducted to examine feeding habits and food resources of the filter-feeding Trichoptera Arctopsyche grandis and Brachycentrus occidentalis along a regulated mountain stream gradient. There was a well defined longitudinal species replacement with A. grandis reaching maximum densities 2.3 kilometers below the impoundment, and concomitant with its decline downstream was an increase in B. occidentalis. At all sampling sites the < 75 µm organic seston fraction usually consisted primarily of diatoms (>70%, by areal estimate on microscope slides), whereas the 75–250 µm and > 250 µm seston fractions were predominantly composed of detritus (> 80 %). B. occidentalis larvae consumed primarily detritus and diatoms (> 70 % of the diet), while A. grandis ingested a variety of materials with animals, detritus and/or filamentous algae often constituting > 80% of the diet. Animal material was over-represented in the diets of both species when compared with amounts in the seston. Feeding habits provided partial explanations for the distinct longitudinal distribution patterns of filter-feeding Trichoptera observed in the regulated river.