Aquatic Insect Larvae Research Articles

Age, Growth, Sex Composition, and Diet of the Burbot, Lota lota, the Only Freshwater Species of the Family Lotidae in the Amur (Heilongjiang) River, Northeast China

Information about the population structure, including the age and sex composition, growth characteristics, and diet of fish, is essential for the conservation and sustainable exploitation of fish stock. The burbot, Lota lota, is the only freshwater species of the family Lotidae in the Amur (Heilongjiang) River catchment located in northeastern China. Information on the biological characteristics and data on the population structure of this fish from the Amur River are scarce. To study these factors in burbot, Lota lota, in the Amur River of China, 749 specimens from four sampling areas were taken and analyzed in October 2022, January 2023, and May 2023. The ages of the sampled fish ranged from 1+ to 7+ years. The female/male ratio was 1.04:1, and body length and mass varied from 175 to 595 mm and 73.5 to 1958.7 g, respectively. The length–weight regression parameter b value was estimated as 2.80. The parameters of the von Bertalanffy growth model were L∞ = 596, K = 0.221, and t0 = −0.771 for all sampled fish; L∞ = 625, K = 0.208, and t0 = −0.756 for females; and L∞ = 584, K = 0.219, and t0 = −0.980 for males. The analysis of the stomach contents showed fish to be the major source of nutrition across all areas and sampling periods. In January, the secondary prey of burbots in the Huma reach of the upper Amur River was aquatic insect larvae, while, in the Tongjiang and Fuyuan reaches of the middle Amur River, the secondary prey was shrimp. The mean stomach fullness index and rate of empty stomachs differed with the sampling area, with the greatest proportion of empty stomachs observed in the Luobei reach of the middle Amur River, and the lowest in the Tongjiang and Fuyuan reaches. The mean stomach fullness index showed the opposite trend. In the Huma reach, the contributions of fish to the diet and the mean stomach fullness index were significantly higher in May than in October and January. The study provides the first detailed information on the population age and sex structure, growth patterns, and feeding ecology of burbots from the Amur River, China. The results will aid in formulating management strategies and regulations for local populations of burbots in the Amur River, China.

Functional traits of predators and decomposer prey determine context dependency in trophic control over ecosystems.

Research Highlight: Piccoli, G. C. d. O., Antiqueira, P. A. P., Srivastava, D. S., & Romero, G. Q. (2024). Trophic cascades within and across ecosystems: The role of anti-predatory defences, predator type and detritus quality. Journal of Animal Ecology, 00, 1-14. https://doi.org/10.1111/1365-2656.14063. Ecosystem functioning is controlled by the interplay between bottom-up supply of limiting nutrients and top-down animal feedback effects. However, the degree of animal versus nutrient control is context-dependent. A key challenge lies in characterizing this context dependency which is hypothesized to depend on differences in animal functional traits. Reporting on an important experiment, Piccoli etal. (2014) evaluate how interactions among functionally different predators and decomposer prey create context dependency in top-down control of a model system-tropical bromeliad tank ecosystems. Bromeliad plants hold water in their tanks supporting microcosm ecosystems containing terrestrial and aquatic insect larvae and arachnids. The ecosystems are supported by nutrients in plant litter that rains down from forest canopies into the tanks. Nutrients are released after litter is decomposed by a functionally diverse community of larval insect decomposers that differ in feeding mode and antipredator defence strategy. This decomposer community is preyed upon by an exclusively narrowly ranging aquatic insect larval predator and widely ranging spider predator that crosses between the aquatic and surrounding terrestrial ecosystems. Experimental manipulation of the animal community to test for the degree of control by predators mediated by the functionally diverse prey community included four treatments: (i) a control with the detritivores composing different function groups but without predators, (ii) the cross-ecosystem spider predator added, (iii) the purely aquatic damselfly larvae predator added and (iv) both predator types added to capture their interacting effect on ecosystem function (decomposition, nutrient release, and plant growth). Notably, the study resolved the causal pathways and strengths of direct and indirect control using structural equation modelling. These findings reveal how context dependency arises due to different capacities of the predators alone and together to overcome prey defences and control their abundances, with attendant cascading effects that diminished as well as enhanced decomposition and nutrient release to support bromeliad plant production. The study reveals that predators have a decided, albeit qualitatively and quantitatively different, hand in shaping the degree of bottom-up control through feedback effect on the release of limiting nutrients. This ground-breaking study provides a way forward in understanding the mechanisms determining context dependency in the control over ecosystem functioning.

Seasonal Diet Changes and Trophic Links of Cold-Water Fish (Coregonus albula) within a Northern Lake Ecosystem

The seasonal feeding patterns of the cold-adapted fish, Coregonus albula, are poorly studied in high-latitude lakes but could provide insight for predicting the effects of global warming. We examined vendace’s diet composition, traced the carbon and nitrogen isotope ratios from producers to consumers in the food web, and estimated vendace’s trophic position in a subarctic lake (the White Sea basin). Results showed the vendace to be a typical euryphagous fish, but clear seasonal differences were found in the relative importance of plankton and benthos in the diet. The vendace consumed primarily benthic amphipods in the summer, planktonic cladocerans in the autumn, and copepods in the winter–spring (under ice); larvae of aquatic insects were the second-most important food items throughout the year. Because of the substantial proportion of fish embryos in its diet, the vendace had a trophic position similar to that of a predatory fish (perch). The Bayesian food source-mixing model revealed that the majority of vendace energy derives from planktonic copepods. The dominant Cyclops had the lowest carbon isotope values, suggesting a carbon-depleted diet typical for methanotrophic bacteria, as its probable food source was in a lake under ice. Understanding the feeding patterns of vendace provides information to better predict the potential biotic effects of environmental change on lake ecosystems.

Water quality parameters and population of aquatic insect larvae in Pardi Lake, Gadchiroli District (M.S.) of India

The present research deals with the study on some physicochemical parameters and the population of aquatic insect and insect larvae of Pardi lake, Gadchiroli which was carried out from February 2016 to January 2017. Total 10 genera of aquatic insect larvae recorded during the present piece of investigation, among which Order Diptera is represented by 07 genera and Coleoptera by 03 genera. The Dipteran species are found to be dominant in the lake. The high density of pollution indicator species like Chironomus, Eristalis and Trichoptera larvae indicates the polluted nature of the lake. Thus, keeping in view the importance of the study, the necessary steps should be taken for the conservation and maintenance of lake.

Состояние кормовой базы бентосоядных рыб малого водоема на водосборе Онежского озера (Республика Карелия)

Knowledge of the conditions of fish existence, one of the elements of which are the conditions of their fattening, allows us to determine the ways of rational use of fish production resources of the reservoir. The research was carried out by means of complex expedition observations in the summer-autumn period of 2017-2021 in the catchment area of Lake Onega (Lake Munozero, Republic of Karelia). The main criterion for assessing the productivity of reservoir is the indicator of the average biomass of macrozoobenthos. For Lake Munozero, it is equal to 3.6 g/m2 in the littoral zone, and 2.73 in the deep-water part. The average number of bottom organisms reaches 2.73 thousand specimens/m2 in the coastal zone of the reservoir, 1.14 thousand specimens/m2 in the profundal. Gastropods (34.9%) and equal–legged crayfish (22.4%) play a significant role in the composition of the biomass of the coastal zone of the lake. The remaining groups of macrozoobenthos are inferior to Gastropoda and Isopoda. Thus, larvae of large-winged insects make up 12.5% of the total biomass, and larvae of chironomids – 10.7%. Representatives of other groups of aquatic invertebrates: small-scale worms, beetles, mayflies, etc. – in the feed supply, they have practically no value and account for less than 6% of benthos biomass. In the deep-water part of the reservoir, the value of relict crustaceans in the macrozoobenthos should be noted in terms of food. Amphipods in terms of biomass 2.7 g/m2 (98%), with a population of 1 thousand individuals/m2 (89.5% of the total number of macrozoobenthos) significantly exceed all the present groups of benthic fauna, which forms the basis of the food base for the ichthyofauna of Profundal. The main importance in the taxonomic composition of the macrozoobenthos of the reservoir are aquatic insect larvae. Quantitatively, among all groups of zoobenthos, the larvae of chironomids or bell mosquitoes (family Chironomidae) dominate, which are not only widespread in the lake, but at the same time achieve a fairly large qualitative diversity. The data obtained can be used to assess fish stocks in Lake Munozero.

Diet in phenotypically divergent sympatric species of African weakly electric fish (genus: Campylomormyrus)-A hybrid capture/HTS metabarcoding approach.

Ecological speciation within the mormyrid genus Campylomormyrus resulted in sympatric species exhibiting divergence in their feeding apparatus and electric organ discharge (EOD). This study documents the overall diet of the genus Campylomormyrus and examines the hypothesis that the Campylomormyrus radiation is caused by adaptation to different food sources. We performed diet assessment of five sympatric Campylomormyrus species (C. alces, C. compressirostris, C. curvirostris, C. tshokwe, C. numenius) and their sister taxon Gnathonemus petersii with markedly different snout morphologies and EODs using hybrid capture/HTS DNA metabarcoding of their stomach contents. Our approach allowed for high taxonomic resolution of prey items, including benthic invertebrates, allochthonous invertebrates and vegetation. Comparisons of the diet compositions using quantitative measures and diet overlap indices revealed that all species are able to exploit multiple food niches in their habitats, that is fauna at the bottom, the water surface and the water column. A major part of the diet is larvae of aquatic insects, such as dipterans, coleopterans and trichopterans, known to occur in holes and interstitial spaces of the substrate. The results indicate that different snout morphologies and the associated divergence in the EOD could translate into different prey spectra. This suggests that the diversification in EOD and/or morphology of the feeding apparatus could be under functional adaptation.

Mercury Isotope Values in Shoreline Spiders Reveal the Transfer of Aquatic Mercury Sources to Terrestrial Food Webs.

The transfer of aquatic contaminants, including mercury (Hg), to terrestrial food webs is an often-overlooked exposure pathway to terrestrial animals. While research has implemented the use of shoreline spiders to assess aquatic to terrestrial Hg transfer, it is unclear whether Hg sources, estimated from isotope ratios, can be successfully resolved to inform site assessments and remedy effectiveness. To examine aquatic to terrestrial Hg transfer, we collected shoreline spiders (Tetragnatha spp.) and aquatic insect larvae (suborder Anisoptera) across a mosaic of aquatic and shoreline habitats in the St. Louis River and Bad River, tributaries to Lake Superior. The fraction of industrial Hg in sediments was reflected in the δ202Hg values of aquatic dragonfly larvae and predatory fish, connecting benthic Hg sources to the aquatic food web. Shoreline spiders mirrored these aquatic Hg source signatures with highly positive correlations in δ202Hg between tetragnathids and dragonfly larvae (r2 = 0.90). Further assessment of different spider taxa (i.e., araneids and pisaurids) revealed that differences in prey consumption and foraging strategies resulted in isotope differences, highlighting the importance of spider taxa selection for Hg monitoring efforts.

Effects of bigheaded carp on larval Freshwater Drum diets

AbstractObjectiveWe investigated foraging success, diet composition, and the abundances of various prey taxa in the diets of larval Freshwater Drum Aplodinotus grunniens across a gradient of bigheaded carp (Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix) relative abundance and in relation to zooplankton density, temperature, discharge, and larval fish densities in the upper Mississippi River (UMR).MethodsWe sampled fish larvae and zooplankton every 10 days (May–August 2017 and 2018) from UMR Pools 14, 16, and 18–20; collected environmental data from nearby gauging stations; and assessed bigheaded carp relative abundance.ResultCrustacean zooplankton abundance was positively related to larval foraging success. Copepods were the dominant prey, but larvae also consumed large proportions of rotifer eggs and benthic insect larvae. Bigheaded carp presence and catch per unit effort were positively associated with increased larval consumption of atypical prey (rotifer eggs and aquatic insect larvae) and cyclopoid copepods. Cladocerans were the rarest prey consumed by larvae in pools where bigheaded carp were present, but they were more frequently consumed in pools where bigheaded carp were absent. In addition to bigheaded carp abundance, river discharge was negatively associated with larval consumption of cladocerans, aquatic insect larvae, and rotifers; water temperature was negatively associated with the consumption of copepods and cladocerans; and rotifer abundance was positively associated with their consumption.ConclusionWe suggest that bigheaded carp alter larval fish diets to prey that may be less energetically beneficial, which can have implications for larval growth and survival.

Gut flora alterations among aquatic firefly Aquatica leii inhabiting various dissolved oxygen in fresh water

Knowledge about the impact of different dissolved oxygen (DO) on the composition and function of gut bacteria of aquatic insects is largely unknown. Herein, we constructed freshwater environments with different DOs (hypoxia: 2.50± 0.50, normoxia: 7.00± 0.50, and hyperoxia: 13.00± 0.50mg/L) where aquatic firefly Aquatica leii larvae lived for three months. Their gut flora was analyzed using the combination of 16S rRNA amplicon sequencing and metagenomics. The results showed no difference in alpha diversity of the gut flora between A.leii inhabiting various DOs. However, the relative abundance of several bacterial lineages presented significant changes, such as Pseudomonas. In addition, bacterial genes with an altered relative abundance in response to various DOs were primarily related to metabolism. The alteration of these functions correlated with the DO change. This is the first to uncover structure of gut flora under various DOs in aquatic insect larvae.

A Note on Diversity of Aquatic Insects in Rivers of Royal Belum State Park, Perak

Royal Belum State Park is one of the oldest, protected and pristine land masses that joins hundreds of small tributaries that feed Lake Temenggor. A scientific expedition was conducted, and the diversity of aquatic insects was studied. Five rivers namely Sungai Ta Ng, Sungai Papan, Sungai Gen, Sungai Ruok and Sungai Rambutan were chosen. A kick-sampling technique was deployed to collect the aquatic insect larvae. The study recorded a total of 42 families and 61 genera of aquatic insects which Sungai Papan has the largest number of taxa recorded (18 families, 26 genera). The number of intolerant taxa (Ephemeroptera, Plecoptera, Trichoptera; EPT) in Sungai Papan was substantial (15 genera). Odonata was discovered to be the most diverse order (13 genera), followed by Ephemeroptera (10 genera) and Trichoptera (10 genera). The findings provided a concise richness of aquatic insects, which might serve as a good tool for evaluating the conservation needs of the area.

Экология, биология и питание хариуса (Thymallus thymallus Linnaeus, 1758) р. Сотки Пинежского государственного заповедника

European grayling Thymallus thymallus (Linnaeus, 1758) is the most valuable nonmigratory species in the ichthyofauna of the Pinezhsky Reserve. The grayling’s habitat inside the specially protected natural area is the Sotka river - the main attraction in the Reserve - flowing through its karst gorges. There are presented the results of comprehensive ichthyological study of grayling population in the Sotka river. Data on the ecology, biology, linearly-weight characteristics and age structure of the population are given. It was found out that grayling prefers the water areas with a mountainous (fast) flow, where it dominates among the fish species and forms a core of the local ichthyocenosis. Specific features of nutrition and age-related changes in the grayling diet have been studied. The 18 taxonomic groups of invertebrates, vertebrates and aquatic vegetation were registered in the food spectrum. The nutrition grayling base in the summer was presented by benthic larvae of amphibiotic insects, planktonic and nektonic organisms. The older species had a narrower range of nutrition based on ground-air insects, while the juveniles' diet was dominated by aquatic insect larvae. By the nature of nutrition, graylings in the river Sotka are euryphages, whose basic diet consists of arthropods. The multi-age structure and abundant population indicates prosperous state of these species.

Diversity of zooplankton in Kadalundi-Vallikunnu Community Reserve, North Kerala, India

Zooplankton samples collected from ten stations covering the entire stretch of the Kadalundi-Vallikunnu CommunityReserve, Kerala, south India, for a period from July 2018 to June 2019 were studied. Twenty eight groups of zooplankton viz. copepods, foraminifera, medusae, chaetognaths, siphonophores, ctenophores, ostracods, cladocera, Lucifer sp., amphipods, isopods, appendicularia, Balanus nauplii, cyphonautes larvae, polychaete larvae, echinoderm larvae, ephyra larvae, brachiopod larvae, alima larvae of squilla, aquatic insect larvae, prawn larvae, crab zoea, crab megalopa larvae, bivalve larvae, pteropods, gastropod larvae, fish eggs and fish larvae were recorded. Among these, copepods formed the major portion of 43%. An average of 18330 nos. per 100 m3 was noticed from the study area. The maximum and minimum density of zooplankton was observed at Station 1 and 10 respectively and a decreasing trend in abundance was recorded from barmouth towards upstream stations. Seasonal studies indicated a maximum of 52% during pre-monsoon, followed by 36% during post-monsoon and a minimum of 12% during monsoon. Different indices of diversity, dominance plot, dendrogram and Multi Dimensional Scaling (MDS) plot are presented and discussed. Keywords: Biodiversity, Estuary, PRIMER, Primary consumers, Seasonality

Increased Mercury and Reduced Insect Diversity in Linked Stream-Riparian Food Webs Downstream of a Historical Mercury Mine.

Historical mining left a legacy of abandoned mines and waste rock in remote headwaters of major river systems in the western United States. Understanding the influence of these legacy mines on culturally and ecologically important downstream ecosystems is not always straightforward because of elevated natural levels of mineralization in mining-impacted watersheds. To test the ecological effects of historic mining in the headwaters of the upper Salmon River watershed in Idaho (USA), we measured multiple community and chemical endpoints in downstream linked aquatic-terrestrial food webs. Mining inputs impacted downstream food webs through increased mercury accumulation and decreased insect biodiversity. Total mercury (THg) in seston, aquatic insect larvae, adult aquatic insects, riparian spiders, and fish at sites up to 7.6 km downstream of mining was found at much higher concentrations (1.3-11.3-fold) and was isotopically distinct compared with sites immediately upstream of mining inputs. Methylmercury concentrations in bull trout and riparian spiders were sufficiently high (732-918 and 347-1140 ng MeHg g-1 dry wt, respectively) to affect humans, birds, and piscivorous fish. Furthermore, the alpha-diversity of benthic insects was locally depressed by 12%-20% within 4.3-5.7 km downstream from the mine. However, because total insect biomass was not affected by mine inputs, the mass of mercury in benthic insects at a site (i.e., ng Hg m-2 ) was extremely elevated downstream (10-1778-fold) compared with directly upstream of mining inputs. Downstream adult aquatic insect-mediated fluxes of THg were also high (~16 ng THg m-2 day-1 ). Abandoned mines can have ecologically important effects on downstream communities, including reduced biodiversity and increased mercury flux to higher order consumers, including fish, birds, and humans. Environ Toxicol Chem 2022;41:1696-1710. Published 2022. This article is a U.S. Government work and is in the public domain in the USA.

Facile green approach for solar energy assisted biogenic nanoparticles synthesis mediated by seed kernel aqueous extract of Trichosanthes tricupsidata and its potential biomedical applications

In this study, an eco-friendly approach is developed to green synthesize AgNPs using seed kernel aqueous extract of the bitter snake gourd, Trichosanthes tricupsidata (Tt). The biophysical properties of Tt-AgNPs formed under ideal conditions were characterized using UV–visible spectrophotometer, X-ray diffraction, Fourier transform infrared, and high-resolution transmission electron microscopy analyses. Tt-AgNPs showed substantial antibacterial activity against eight Gram-negative and five Gram-positive bacterial pathogens tested. Hemolytic assay performed against human-A erythrocytes ensured the biocompatibility of Tt-AgNPs at 2.8% of hemolysis that showed the standard requirements for nanoparticles hemolytic properties. Tt-AgNPs showed dose-dependent larval anti-mosquito activity against fourth instar larvae Aedes aegypti. Larval mortality of 100% was observed with highest concentration and the 24 h LC50 and LC90 values were found to be 233.18 and 446.22 µg/mL, respectively. No lethal effect was observed on non-target aquatic insect larvae Chironomus costatus. The overall findings of the study revealed the Tt-AgNPs are suitable for its potential biomedical applications.

Extreme suction attachment performance from specialised insects living in mountain streams (Diptera: Blephariceridae).

Suction is widely used by animals for strong controllable underwater adhesion but is less well understood than adhesion of terrestrial climbing animals. Here we investigate the attachment of aquatic insect larvae (Blephariceridae), which cling to rocks in torrential streams using the only known muscle-actuated suction organs in insects. We measured their attachment forces on well-defined rough substrates and found that their adhesion was less reduced by micro-roughness than that of terrestrial climbing insects. In vivo visualisation of the suction organs in contact with microstructured substrates revealed that they can mould around large asperities to form a seal. We have shown that the ventral surface of the suction disc is covered by dense arrays of microtrichia, which are stiff spine-like cuticular structures that only make tip contact. Our results demonstrate the impressive performance and versatility of blepharicerid suction organs and highlight their potential as a study system to explore biological suction mechanisms.

Quantification of Biodriven Transfer of Per- and Polyfluoroalkyl Substances from the Aquatic to the Terrestrial Environment via Emergent Insects.

Emergent aquatic insects are important food subsidies to riparian food webs but can also transfer waterborne contaminants to the terrestrial environment. This study aimed to quantitatively assess this biodriven transfer for per- and polyfluoroalkyl substances (PFAS). Aquatic insect larvae, emergent aquatic insects, terrestrial consumers, sediment, and water were collected from a contaminated lake and stream and an uncontaminated pond, and analyzed for PFAS and stable isotopes of carbon and nitrogen. Top predators in this study were spiders, which showed the highest average ∑24PFAS concentration of 1400 ± 80 ng g–1 dry weight (dw) at the lake and 630 ng g–1 dw at the stream. The transfer of PFAS from the lake to the riparian zone, via deposition of emergent aquatic insects, was 280 ng ∑24PFAS m–2 d–1 in 2017 and only 23 ng ∑24PFAS m–2 d–1 in 2018. Because of higher production of emergent aquatic insects, the lake had higher PFAS transfer and higher concentrations in terrestrial consumers compared to the stream, despite the stream having higher PFAS concentration in water and aquatic insect larvae. Our results indicate that biodriven transfer of PFAS from the aquatic systems and subsequent uptake in terrestrial food webs depend more on emergence amounts, i.e., aquatic prey availability, rather than on PFAS concentrations in water and aquatic prey.

Food items and feeding habits of two Nothobranchiidae, Epiplatys chaperi sheljuzhkoi (poll, 1953) and Nimbapanchax petersi (sauvage, 1882) in Banco river, Côte d’ivoire

Food and feeding habits of two Nothobranchiidae species, Epiplatys chaperi sheljuzhkoi (Poll, 1953) and Nimbapanchax petersi (Sauvage, 1882) from Banco River were investigated between January and December 2016. Stomach contents of 119 and 397 individuals of E. sheljuzhkoi and N. petersi were respectively analyzed, ranging in size from 13 and 55 mm, 11 and 48 mm standard Length, respectively. Formicidae being terrestrial insects, constituted the main prey (RI>50) of both species, and aquatic insect larvae (Hydrophilidae and Chironomidae) were secondary or accessory preys. The food items in stomach showed a small spectrum in E. sheljuzhkoi than N. petersi but differences were not significant (Chi-square, p>0.05). Diet composition of both species showed little variation according to seasons, sampling zones and size groups (Anova, p>0.05). However, a decreasing trend in terrestrial insects and an increase of other preys in stomach contents has been observed from upstream to downstream. For ontogenic variation, large specimens group fed much more on aquatic insect larvae, fish scales and macrophytes than small size group. This work indicated that both species fed on a small range of prey items dominated by insects in Banco River and could be considered strict insectivorous predators. This work concludes that both species have similar diets and the canopy cover of Banco forest plays an important role in the feeding and conservation of these species.
 Key words: Epiplatys, Nimbapanchax, canopy cover, diet, terrestrial insects, Formicidae, predator.

Florivory by the occupants of phytotelmata in flower parts can decrease host plant fecundity.

Some types of plant accumulate liquid in their inflorescences creating phytotelmata. These environments protect the flowers against florivory, although they may be colonized by aquatic or semi-aquatic florivorous insect larvae, whose effects on the fitness of the plants remain unclear. We tested the hypothesis of floral antagonism by the occupants of phytotelmata, which predicts that florivory by the occupants of the phytotelmata represents a cost to the female fitness of the plant, reducing its fecundity. We manipulated experimentally the infestation by 3 florivores larvae species occupants of phytotelmata in inflorescences of Heliconia spathocircinata (Heliconiaceae) to test for negative direct trophic effects on the fecundity of the flowering and fruiting bracts. We found that the foraging of the hoverfly (Syrphidae) and moth (Lepidoptera) larvae in the inflorescences contributed to a decline in the fecundity of the plant. While the lepidopteran impacted fecundity when foraging in both flowering and fruiting bracts, the syrphid only affected the fruiting bracts, which indicates that the nectar and floral tissue are the principal resource exploited by the hoverfly. By contrast, soldier fly (Stratiomyidae) had a neutral effect on fecundity, while foraging in flowering or fruiting bracts. These findings corroborate our hypothesis, that herbivory by the larval occupants represents cost to the host plant having phytotelmata. The negative influence of this foraging on plant fecundity will nevertheless depend on the consequences of the exploitation of resources, which vary considerably in ephemeral habitats such as the phytotalmanta of flower parts.

Variation in metal concentrations across a large contamination gradient is reflected in stream but not linked riparian food webs

Aquatic insects link food web dynamics across freshwater-terrestrial boundaries and subsidize terrestrial consumer populations. Contaminants that accumulate in larval aquatic insects and are retained across metamorphosis can increase dietary exposure for riparian insectivores. To better understand potential exposure of terrestrial insectivores to aquatically-derived trace metals, metal concentrations in water and tissues were analyzed from different components of streams and riparian food webs across a large (2–3 orders of magnitude) metal gradient (e.g., Zn, Cu, Cd, Pb) in the Rocky Mountains (USA). Our research indicates that the trace metal concentration gradient present among streams was lost during metamorphosis of aquatic larval insects into terrestrially flying adults, decoupling terrestrial exposures from aquatic concentrations. This pattern was caused by declines in 1) among-stream variation in trace metal concentrations, 2) relationships between metal concentrations in paired water and food web components, and 3) mean metal concentrations within aquatic food webs and across the aquatic-terrestrial boundary. Specifically, among-stream variation in trace metal concentrations was highest for water and aquatic vegetation, intermediate for aquatic insect larvae (~30% lower than water) and lowest for adult aquatic insects and riparian spiders (~65% lower). Metal concentrations in paired water and food web components ranged from highly related across the stream-metal gradient (slopes ~1) for water and aquatic vegetation, to less related (slopes closer to 0) for aquatic vegetation and aquatic insect larvae, to unrelated (slopes ~0) for aquatic larval and adult insects. Finally, mean metal concentrations were highest in aquatic vegetation and lowest in adult aquatic insects emerging from streams (~50% lower than aquatic vegetation). Our results indicate less efficient trophic transfer and higher metamorphic loss of trace metals from high metal streams (i.e., exposure-dependent transfer). For many trace metals, aquatic-terrestrial dietary transfer is unlikely to be an important source of exposure for terrestrial insectivores of adult aquatic insects.

Variasi Pemberian Bioton terhadap Kelimpahan Moina sp.

Fish after the egg-bag absorption phase require external feeding, in the form of fresh natural food organisms, such as phytoplankton, zooplankton, or aquatic insect larvae. These natural food organisms are limited in number. The business of mass production of natural food is still limited to several types originating from marine or brackish waters. For this type of natural freshwater fish feed, it is still limited to experimental materials. This study aims to determine the best dosage of Bioton liquid fertilizer added to the maintenance medium to the rate of population abundance of Moina sp. The research was conducted at the Wet Laboratory of Fisheries Cultivation Study Program, Faculty of Agriculture, Ahmad Yani University, Banjarmasin. The method used in this study was an experiment with a completely randomized design of 4 treatments and 3 replications. The treatment applied was 4 treatments with 3 repetitions, with the following treatment of Bioton liquid fertilizer: A = 5 ml / 3 l water, B = 10 ml / 3 l water, C = 15 ml / 3 l water, and D = without Bioton liquid fertilizer (control). The results showed that the abundance of Moina sp in treatment A = 4,333 ind / l, B = 3,633 ind / l, C = 2,700 ind / l and D = 3,034 ind / l. The ANOVA test results of all treatments were very significantly different, so accept H1, namely giving bioton with different doses had a significant effect on the abundance of Moina sp. The results of the LSD test of all treatments had a very significant difference in abundance, except for treatment D to treatment C which was significantly different, with the best treatment being a dose of 5 ml / 3 l of water (treatment A).