[Monoamine-containing structures in the central nervous system in Trichoptera (Insecta). II].
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Amines↗
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[A contribution to the knowledge of the geographic variability of Rhadicoleptus alpestris Kol. (Trichoptera, Limnephilidae)].
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Ecology↗
[First chromosome observations in the germary of Potamophylax cingulatus Steph. female and Halesus radiatus curt. female (Trichoptera, Limnephilidae) (author's transl)].
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Animals↗
Chronic Toxicity of Ammonia to New Zealand Freshwater Invertebrates: A Mesocosm Study.
Freshwater macroinvertebrate communities were established within 12 artificial streams or "toroidal" mesocosms and exposed to three replicated concentrations of ammonia for 29 days at constant temperature (16 degrees C) and pH (median 8.4). The criterion units (CU = measured [ammonia]/US EPA 1985 chronic criterion value) of total ammonia in the LOW, MED, and HIGH treatments were 2.0, 4.8, and 13 CUs respectively, and 1.9, 5.8, and 12 CUs for the unionized ammonia. Macroinvertebrates were tolerant of the ammonia exposures with no significant (p > 0.1) effect on taxa richness; number of taxa in the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT); or the quantitative macroinvertebrate community index (QMCI), a biotic index proposed for assessing effects of organic enrichment in New Zealand streams. Significant differences (p < 0.05) occurred for the mean abundance and the numbers of EPT individuals (QEPT), with the HIGH treatment significantly lower (-41%) than the control for both abundance and QEPT. Of the major species, only the mayflies Deleatidium sp. (Ephemeroptera: Leptophlebiidae) and Coloburiscus humeralis (Ephemeroptera: Oligoneuriidae) showed significant reductions in abundance, with only the caddisflies Beraeoptera roria (Trichoptera: Conoesucidae) and Confluens sp. (Trichoptera: Conoesucidae) showing significant increases in abundance. The abundance of juvenile Deleatidium sp. had a negative concentration-response relationship that resulted in an 82% decrease in abundance in the HIGH treatment. Drift of invertebrates showed no response to ammonia treatments. The 29-day EC(50) values for Deleatidium sp. for total and unionized ammonia were 2.15 mg (N)/L (pH 8.4) and 0.145 mg (NH(3)-N)/L. No observed effect concentration (NOEC) values were 0.95 mg (N)/L and 0.066 mg (NH(3)-N)/L, and the threshold effect concentration (TEC) was 1.49 mg (N)/L and 0.102 mg (NH(3)-N)/L. Comparison of the Deleatidium sp. chronic ammonia sensitivity data with the US EPA 1985 chronic criterion value (CCC = 0.45 mg [N]/L, pH 8.4, 16 degrees C) showed the TEC value for total ammonia was 3.3x CCC, and 2.2x higher than the updated US EPA 1998 criteria. The findings suggest that use of the US EPA criteria would provide minimal protection for Deleatidium for chronic ammonia exposure, and that development of site-specific criteria, covering a wide range of environmental conditions, may be required to adequately protect this species.http://link.springer-ny.com/link/service/journals/00244/bibs/37n3p338.html
Journal Article↗
The Strepsiptera problem: phylogeny of the holometabolous insect orders inferred from 18S and 28S ribosomal DNA sequences and morphology.
Phylogenetic relationships among the holometabolous insect orders were inferred from cladistic analysis of nucleotide sequences of 18S ribosomal DNA (rDNA) (85 exemplars) and 28S rDNA (52 exemplars) and morphological characters. Exemplar outgroup taxa were Collembola (1 sequence), Archaeognatha (1), Ephemerida (1), Odonata (2), Plecoptera (2), Blattodea (1), Mantodea (1), Dermaptera (1), Orthoptera (1), Phasmatodea (1), Embioptera (1), Psocoptera (1), Phthiraptera (1), Hemiptera (4), and Thysanoptera (1). Exemplar ingroup taxa were Coleoptera: Archostemata (1), Adephaga (2), and Polyphaga (7); Megaloptera (1); Raphidioptera (1); Neuroptera (sensu stricto = Planipennia): Mantispoidea (2), Hemerobioidea (2), and Myrmeleontoidea (2); Hymenoptera: Symphyta (4) and Apocrita (19); Trichoptera: Hydropsychoidea (1) and Limnephiloidea (2); Lepidoptera: Ditrysia (3); Siphonaptera: Pulicoidea (1) and Ceratophylloidea (2); Mecoptera: Meropeidae (1), Boreidae (1), Panorpidae (1), and Bittacidae (2); Diptera: Nematocera (1), Brachycera (2), and Cyclorrhapha (1); and Strepsiptera: Corioxenidae (1), Myrmecolacidae (1), Elenchidae (1), and Stylopidae (3). We analyzed approximately 1 kilobase of 18S rDNA, starting 398 nucleotides downstream of the 5' end, and approximately 400 bp of 28S rDNA in expansion segment D3. Multiple alignment of the 18S and 28S sequences resulted in 1,116 nucleotide positions with 24 insert regions and 398 positions with 14 insert regions, respectively. All Strepsiptera and Neuroptera have large insert regions in 18S and 28S. The secondary structure of 18S insert 23 is composed of long stems that are GC rich in the basal Strepsiptera and AT rich in the more derived Strepsiptera. A matrix of 176 morphological characters was analyzed for holometabolous orders. Incongruence length difference tests indicate that the 28S + morphological data sets are incongruent but that 28S + 18S, 18S + morphology, and 28S + 18S + morphology fail to reject the hypothesis of congruence. Phylogenetic trees were generated by parsimony analysis, and clade robustness was evaluated by branch length, Bremer support, percentage of extra steps required to force paraphyly, and sensitivity analysis using the following parameters: gap weights, morphological character weights, methods of data set combination, removal of key taxa, and alignment region. The following are monophyletic under most or all combinations of parameter values: Holometabola, Polyphaga, Megaloptera + Raphidioptera, Neuroptera, Hymenoptera, Trichoptera, Lepidoptera, Amphiesmenoptera (Trichoptera + Lepidoptera), Siphonaptera, Siphonaptera + Mecoptera, Strepsiptera, Diptera, and Strepsiptera + Diptera (Halteria). Antliophora (Mecoptera + Diptera + Siphonaptera + Strepsiptera), Mecopterida (Antliophora + Amphiesmenoptera), and Hymenoptera + Mecopterida are supported in the majority of total evidence analyses. Mecoptera may be paraphyletic because Boreus is often placed as sister group to the fleas; hence, Siphonaptera may be subordinate within Mecoptera. The 18S sequences for Priacma (Coleoptera: Archostemata), Colpocaccus (Coleoptera: Adephaga), Agulla (Raphidioptera), and Corydalus (Megaloptera) are nearly identical, and Neuropterida are monophyletic only when those two beetle sequences are removed from the analysis. Coleoptera are therefore paraphyletic under almost all combinations of parameter values. Halteria and Amphiesmenoptera have high Bremer support values and long branch lengths. The data do not support placement of Strepsiptera outside of Holometabola nor as sister group to Coleoptera. We reject the notion that the monophyly of Halteria is due to long branch attraction because Strepsiptera and Diptera do not have the longest branches and there is phylogenetic congruence between molecules, across the entire parameter space, and between morphological and molecular data.
Animals↗
[Longitude variability of macrobenthos in the streams of Central European Russia].
The changes in macrobenthos community depended on changes in stream discharge (from 0.001 m3/sec to 100 m3/sec) were studied on the basis of data from 254 stations of 180 streams located in the centre of European part of Russia. While discharge of stream increases community composition changes considerably. Species diversity increases from 12 to 47 species per station with the increase in stream size. Moreover, the diversity of almost all groups, discerned according habitat or trophic position and main taxonomic groups (with the exception of Plecoptera and Diptera) increases with the increase in stream discharge. The diversity of lithorheophilic species and species inhabiting soft substrates is higher in small streams, whereas phitophilic species are more diverse in large streams. With the increase in stream size the percent of algophagous and filter feeders increases, percent of carnivorous remains the same and the percent of detritophages decreases. The relative role of invertebrates macrotaxons change with the stream size: in the smallest streams the diversity is the highest among Diptera, Trichoptera and Plecoptera, in medium-size streams--among Trichoptera, Ephemeroptera and Diptera, in large streams--in Ephemeroptera, Gastropoda and Trichoptera. In some groups some species replace other (close-related) in parallel with change in stream discharge however in general this tendency is weak. The index of saprobic conditions increases with the increase in stream size from 1.6-1.7 to 2.3-2.4. In small streams the saprobic conditions are very different whereas large streams have tendency to be at beta-mesosaprobic level. Cluster analysis reveal four size classes of streams. Peculiarities of habitat and macrobenthos fauna of these classes are described.
Animals↗
Comparison of fatty acid composition in major lipid classes of the dominant benthic invertebrates of the Yenisei river.
The composition and content of fatty acids (FAs) in total lipids, triacylglycerols (TAG) and polar lipids (PL) in dominant groups of benthic invertebrates: gammarids (Gammaridae, Amphipoda), chironomid larvae (Chironomidae, Diptera), caddisfly larvae (Trichoptera) and mayfly larvae (Ephemeroptera) were studied in the Yenisei river. For the first time data on the FA composition of species belonging to Trichoptera (Insecta) are presented. The groups of aquatic insect larvae and gammarids weakly differed in total content of essential polyunsaturated fatty acids (PUFAs). Hence, the strong invasion of gammarids which occurred in the last decades in the Yenisei river should not result in a decrease in potential yield of essential PUFA in the ecosystem and corresponding decrease in food resource quality for fish in respect to PUFA content. Significant differences in biomarker FAs in TAG were found which correlated to specific food sources. Different levels of long-chain PUFA in PL of the invertebrates are discussed in relation to the genetic ability of particular taxa to form these FAs.
Analysis of Variance↗
A longitudinal assessment of the aquatic macroinvertebrate community in the channelized lower Missouri River.
We conducted an aquatic macroinvertebrate assessment in the channelized reach of the lower Missouri River, and used statistical analysis of individual metrics and multimetric scores to identify community response patterns and evaluate relative biological condition. We examined longitudinal site differences that are potentially associated with water quality related factors originating from the Kansas City metropolitan area, using data from coarse rock substrate in flowing water habitats (outside river bends), and depositional mud substrate in slack water habitats (dike fields). Three sites above river mile (RM) 369 in Kansas City (Nebraska City, RM = 560; St. Joseph, RM = 530; Parkville, RM = 377) and three below (Lexington, RM = 319; Glasgow, RM = 228; Hermann, RM = 94) were sampled with rock basket artificial substrates, a qualitative kicknet method, and the Petite Ponar. We also compared the performance of the methods used. A total of 132 aquatic macroinvertebrate taxa were collected from the lower Missouri River; one third of these taxa belonged to the sensitive EPOT insect orders (Ephemeroptera, Plecoptera, Odonata, and Trichoptera). Rock baskets had the highest mean efficiency (34.1%) of the methods, and the largest number of taxa was collected by Ponar (n = 69) and kicknet (n = 69) methods. Seven of the 15 metrics calculated from rock basket data, and five of the nine metrics calculated from Ponar data showed highly significant differences (ANOVA, P < 0.001) at one or more sites below Kansas City. We observed a substantial reduction in net-spinning Trichoptera in rock habitats below Kansas City (Lexington), an increase in relative dominance of Oligochaeta in depositional habitats at the next site downstream (Glasgow), and lower relative condition scores in rock habitat at Lexington and depositional habitat at Glasgow. Collectively, these data indicate that some urban-related impacts on the aquatic macroinvertebrate community are occurring. Our results suggest that the methods and assessment framework we used in this study could be successfully applied on a larger scale with concurrent water and sediment chemistry to validate metrics, establish impairment levels, and develop a specific macroinvertebrate community index for the lower Missouri River. We recommend accomplishing this with longitudinal multi-habitat sampling at a larger number of sites related to all potential sources of impairment, including major tributaries, urban areas, and point sources.
Animals↗
Impervious surface area as a predictor of the effects of urbanization on stream insect communities in Maine, USA.
The influence of urbanization on stream insect communities was determined by comparing physical, chemical, and biological characteristics of streams draining 20 catchments with varying levels of urban land-cover in Maine (U.S.A). Percent total impervious surface area (PTIA), which was used to quantify urban land-use, ranged from approximately 1-31% among the study catchments. Taxonomic richness of stream insect communities showed an abrupt decline as PTIA increased above 6%. Streams draining catchments with PTIA < 6% had the highest levels of both total insect and EPT (Ephemeroptera + Plecoptera + Trichoptera) taxonomic richness. These streams contained insect communities with a total richness averaging 33 taxa in fall and 31 taxa in spring; EPT richness ranged from an average of 15 taxa in fall and 13 taxa in spring. In contrast, none of the streams draining catchments with 6-27% PTIA had a total richness > 18 taxa or an EPT richness > 6 taxa. Insect communities in streams with PTIA > 6% were characterized by the absence of pollution-intolerant taxa. The distribution of more pollution-tolerant taxa (e.g. Acerpenna (Ephemeroptera); Paracapnia, Allocapnia (Plecoptera); Optioservus, Stenelmis (Coleoptera); Hydropsyche, Cheumatopsvyche (Trichoptera)), however, showed little relation to PTIA. In contrast to the apparent threshold relationship between PTIA and insect taxonomic richness, both habitat quality and water quality tended to decline as linear functions of PTIA. Our results indicate that, in Maine, an abrupt change in stream insect community structure occurs at a PTIA above a threshold of approximately 6% of total catchment area. The measurement of PTIA may provide a valuable tool for predicting thresholds for adverse effects of urbanization on the health of headwater streams in Maine.
Animals↗
Multimetric assessment of nutrient enrichment in impounded rivers based on benthic macroinvertebrates.
In this investigation we evaluated the performance of multiple metrics, based on benthic macroinvertebrates, to assess nutrient enrichment in impounded rivers. Field studies were conducted in the upper reaches of four impounded mountain rivers (Tormes, Riaza, Eresma and Miraflores Rivers) of Central Spain. The watersheds of these rivers are underlain by siliceous rocks. Two sampling sites, upstream and downstream from the reservoir, were established in stony riffles of each impounded river. We used a total of 34 metrics, representing five different metric groups: measures of abundance and richness, percentages of taxonomic groups, percentages of functional feeding groups, measures of dominance and diversity, and biotic indices. Evaluation of different metrics was mainly based on correlation analyses between concentrations of nutrients (NO3-N, NH4-N, PO4-P) and values of individual metrics. Deep releases from the reservoirs were the primary cause responsible for the nutrient enrichment at downstream sampling sites. Chironomidae density, Gastropoda density, % Chironomidae, % Gastropoda, % collector-gatherers and scrapers, proportion of the two most dominant taxa, and Camargo's dominance index exhibited the highest positive correlation coefficients. Conversely, Plecoptera density, Trichoptera density, EPT richness, % Plecoptera, % Trichoptera, % collector-filterers, % predators, % shredders, Simpson's and Camargo's diversity indices, and the average BMWQ score (biotic index) exhibited the highest negative correlation coefficients. Overall it is concluded that the multimetric approach may be a useful technique for the biological assessment of nutrient enrichment in fluvial ecosystems, particularly in upper reaches of siliceous rivers.
Animals↗
Sex chromatin in lepidoptera.
Like mammals, Lepidoptera possess female-specific sex chromatin. In a compilation of new and published data, 81% of the 238 investigated Lepidoptera species display one or more heterochromatin bodies in female somatic interphase cells, but not in male cells. In contrast with the similar phenomenon in mammals, this sex-specific heterochromatin does not function as a dosage compensation mechanism. Most Lepidoptera have a WZ/ZZ sex chromosome mechanism, and the sex chromatin is derived from the univalent W sex chromosome. Sex chromatin is regarded as an indicator of an advanced stage of W chromosome evolution. In species with a Z/ZZ sex chromosome mechanism, loss of the W chromosome is accompanied by loss of the female-specific heterochromatin. Since sex chromatin can be discerned easily in interphase nuclei, and especially so in the highly polyploid somatic cells, it is a useful marker for diagnosing chromosomal sex of embryos and larvae, and of identifying sex chromosome aberrations in mutagenesis screens. All species with sex chromatin belong to the Ditrysia, the main clade of Lepidoptera that contains more than 98% of all extant species. Sex chromatin has not been reported for clades that branched off earlier. The nonditrysian clades share this character with Trichoptera, a sister group of the Lepidoptera. We propose that Lepidoptera originally had a Z/ZZ sex chromosome mechanism like Trichoptera; the WZ/ZZ sex chromosome mechanism evolved later in the ditrysian branch of Lepidoptera. Secondary losses of the W chromosome account for the sporadically occurring Z/ZZ sex chromosome systems in ditrysian families. The lepidopteran sex chromatin, therefore, appears to mirror the full evolutionary life cycle of a univalent sex chromosome from its birth through heterochromatinization to sporadic loss.
Animals↗
Specialized olfactory receptor neurons mediating intra- and interspecific chemical communication in leafminer moths Eriocrania spp. (Lepidoptera: Eriocraniidae).
We performed a physiological and morphological characterization of sensilla auricillica in male Eriocrania semipurpurella moths. Each auricillic sensillum contained three olfactory receptor neurons. Responding neurons (87 of 139) could be grouped into five physiological types. Type 1 responded to (R,Z)-6-nonen-2-ol and type 2 to its enantiomer (S,Z)-6-nonen-2-ol, both of which are pheromone components of E. semipurpurella. Type 3 responded to both (R)-heptan-2-ol and (R,Z)-4-hepten-2-ol, which are pheromone components of the sympatric species E. cicatricella. Types 4 and 5 responded to the ketones (Z)-6-nonen-2-one and/or nonan-2-one, which are found in the pheromone glands of female E. semipurpurella. Field-trapping showed that type 3 receptor neurons mediate strongly antagonistic effects of (R)-heptan-2-ol and (R,Z)-4-hepten-2-ol on E. semipurpurella, while nonan-2-one should possibly be included as a synergist in the sex pheromone blend of this species. The attraction of E. cicatricella and E. sparrmannella to compounds mixed with the pheromone blend of E. semipurpurella shows that the pheromone components of E. semipurpurella have little or no antagonistic effects on these species. The morphology and physiology of eriocraniid pheromone sensilla are very similar to those found in the order Trichoptera (caddisflies), suggesting a homology between pheromone detection systems in the two sister orders Lepidoptera and Trichoptera.
Action Potentials↗
Diet and trophic groups of an aquatic insect community in a tropical stream.
The diet and trophic groups of an assemblage of aquatic insects were studied in a tropical stream. Genera of the orders Ephemeroptera, Odonata, Plecoptera, Lepidoptera, and Hemiptera showed feeding specialization. Others, such as Trichoptera, Coleoptera, and Diptera, showed great diet variation with genera of different trophic groups. Seasonal variation of insect diet, evident only for some genera of the orders Trichoptera, Lepidoptera, Coleoptera, and Diptera, was due to the differences observed in community composition and to generalist habits of these genera. However, the seasonal comparison of trophic groups showed no significant statistical differences. The great importance of organic matter, a non-limited resource, in the diet of Ribeirão do Atalho aquatic insects may be the explanation for the trophic stability in this community organization.
Animals↗
The genome sequence of a caddisfly, Limnephilus auricula (Curtis, 1834).
We present a genome assembly from an individual female Limnephilus auricula (a caddisfly; Arthropoda; Insecta; Trichoptera; Limnephilidae). The genome sequence is 971.3 megabases in span. Most of the assembly is scaffolded into 30 chromosomal pseudomolecules, including the Z sex chromosome. The mitochondrial genome has also been assembled and is 18.29 kilobases in length.
Limnephilus auricula↗
Larval antennal sensilla in water-living insects.
An overview of larval antennal sensilla in hemimetabolous and holometabolous water-living insects is given by updating current knowledge on the fine structure of these sensory systems. In the absence of successful electrophysiological studies, the possible function of sensilla is deduced from their architecture. Various kinds of sensilla are described in hemimetabolous insects, such as Ephemeroptera, Odonata, and Plecoptera, and holometabolous insects, such as Diptera Nematocera (Culicidae, Simuliidae, Psychodidae, Chaoboridae) and Trichoptera. Their possible function in responding to stimuli from the freshwater environment is illustrated and discussed. The importance of sensilla as taxonomic and phylogenetic traits is reported in Baetidae (Ephemeroptera) and in Diptera Nematocera. Some homologies outlined in Diptera Nematocera give evidence of a link between species, such as Chaoboridae and Psychodidae, whose antennae are highly modified, prehensile in the former and very reduced in the latter. Particular features, such as cuticle without pores in chemosensory sensilla and naked perikarya, are so far found exclusively in some water-living arthropods, thus reflecting a possible adaptation to the aquatic habitat. The structure of sensilla and chloride cells, which have a similar external morphology, is presented and discussed in various insect groups, considering the possible derivation of the chloride cells from sensilla.
Animals↗
Leucine transport in brush border membrane vesicles from freshwater insect larvae.
Leucine transport across brush border membrane vesicles prepared from four insect species common to European freshwater streams has been characterized. The species studied were: Ephemera danica (Ephemeroptera: Ephemeridae), Isoperla grammatica (Plecoptera: Perlodidae), Hydropsyche pellucidula (Trichoptera: Hydropsychidae), and Hybomitra bimaculata (Diptera: Tabanidae). The transport differed among the studied taxa for several features, including pH and sodium dependence, substrate affinity and specificity, and efficiency. In H. pellucidula and E. danica, leucine uptake was higher at pH 7.4 than at more alkaline or acidic pH values, whereas in I. grammatica and H. bimaculata, the uptake was rather constant when pH varied from 5.0 to 7.4, then strongly decreased at pH 8.8. All but E. danica displayed a transient intravescicular leucine accumulation in the presence of sodium, suggesting the existence of a cation-leucine symport mechanism. The sodium dependence ranged according to the following order: H. pellucidula > I. grammatica > H. bimaculata > E. danica. Moreover, in H. pellucidula and I. grammatica, the sodium-dependence was stronger at pH 8.8 than at pH 7.4. In E. danica, leucine uptake was sodium-independent at all pH values. The highest value of V(max) (45.3 pmol.s(-1).mg proteins(-1)) was in E. danica, which, however, displayed the lowest affinity (K(m) 137 muM) when compared to the kinetic parameters of other taxa. The V(max) and K(m) values were: 40 and 52.5, 32.1 and 12.5, and 4.5 and 230 for H. bimaculata, H. pellucidula, and I. grammatica, respectively. The obtained results are discussed within our current knowledge of amino acid transport systems in insects.
Animals↗
Phylogeny of a serotonin-immunoreactive neuron in the primary olfactory center of the insect brain.
Serotonin (5-hydroxytryptamine; 5HT) functions in insects as a neurotransmitter, neuromodulator, and neurohormone. In the sphinx moth Manduca sexta, each of the paired antennal lobes (ALs; the primary olfactory centers in the insect brain) has one 5HT-immunoreactive (5HT-ir) neuron that projects into the protocerebrum, crosses the posterior midline, and innervates the contralateral AL; this is referred to as the contralaterally projecting, serotonin-immunoreactive deutocerebral (CSD) neuron. These neurons are thought to function as centrifugal modulators of olfactory sensitivity. To examine the phylogenetic distribution of 5HT-ir neurons apparently homologous to the CSD neuron, we imaged 5HT-like immunoreactivity in the brains of 40 species of insects belonging to 38 families in nine orders. CSD neurons were found in other Lepidoptera, Trichoptera, Diptera, Coleoptera, and Neuroptera but not in the Hymenoptera. In the paraneopteran and polyneopteran species (insects that undergo incomplete metamorphosis) examined, AL 5HT neurons innervate the ispsilateral AL and project to the protocerebrum. Our findings suggest that the characteristic morphology of the CSD neurons originated in the holometabolous insects (those that undergo complete metamorphosis) and were lost in the Hymenoptera. In a subset of the Diptera, the CSD neurons branch within the contralateral AL and project back to the ipsilateral AL via the antennal commissure. The evolution of AL 5HT neurons is discussed in the context of the physiological actions of 5HT observed in the lepidopteran AL.
Animals↗
Correlation between overall pesticide effects monitored by shrimp mortality test and change in macrobenthic fauna in a river.
The relationship between change in benthic fauna in the Suna River and shrimp mortality in the river water samples (test was conducted two times per week from May to September) was investigated to assess the insecticide impact on the benthic community. The river was selected because pesticide application had been restricted for a long time in the upper reaches, while aerial insecticide spraying had been done four times on paddy fields in the lower reaches in summer. Species richness and density of benthos were high at the stations in the upper reaches. High shrimp mortality was measured in the water samples collected from a downstream station during the pesticide spraying period, from late July to late August. Species richness and density of benthos markedly decreased at the stations in the lower reaches in that period. However, several species of chironomids, Cheumatopsyche (Trichoptera), which demonstrated tremendous insecticide resistance, and Baetis sahoensis (Ephemeroptera), which has a high recovery potential, were not affected, even in the insecticide spraying period. The benthic fauna in the lower reaches tended to recover from autumn to spring, although not sufficiently. It is considered that the temporal recovery of the benthic community was brought about through recruitment from the benthic community in the 5-km upper reaches. A close correlation was found between the high mortality of shrimp in the water samples and the deterioration in the benthic fauna in this river which was contaminated with insecticides during the summer.
Animals↗