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Experiments are useful scientific tools for testing hypotheses by manipulating variables of interest while controlling for other factors that can bias or confuse the results and their interpretation. To ensures accuracy and reproducibility, experiments must have transparent and repeatable methodologies. Due to the importance of shredder invertebrates in organic matter processing, carbon cycling, and nutrient cycling, we tested experimentally the effect of different methodological approaches in microcosm experiments on the consumption and survival of shredders. We found that the shredder species, the presence or absence of the case, and the use or non-use of air-pumps in the microcosms did not affect shredder performance (i.e., consumption and survival). Furthermore, the type of water (stream or bottled) did not affect shredder performance. On the other hand, the amount of light had a negative effect on shredder performance, with constant light (i.e., 24 h) reducing shredder consumption and survival. Our results demonstrate that the use of different methodologies does not always result in changes in outcomes, thus ensuring comparability. However, luminosity is a critical factor that deserves attention when conducting microcosm experiments. Our findings provide valuable insights that can assist researchers in designing experiments with shredders from neotropical streams and conducting systematic reviews and meta-analyses.

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We evaluated the effects of seasonality on the richness and abundance of dipterans of the families Calliphoridae and Mesembrinellidae associated with the decomposition of a clothed Large White swine Sus scrofa domesticus(Artiodactyla: Suidae) carcass. Experiments were carried out in less rainy, rainy, and intermediate periods between 2010 and 2011 at Reserva Florestal Ducke, Manaus, Amazonas. Two pig carcasses, each weighing approximately 40 kg, were used in each period. A total of 63,872 individuals of 18 species of Calliphoridae and Mesembrinellidae were collected. The abundance and richness of these dipteran families were influenced by the interaction between period and decomposition stage. The compositions of the Calliphoridae and Mesembrinellidae assemblages differed among periods, with the fauna of the less rainy period being less similar to those of the intermediate and rainy periods than they were to each other. Three species were selected as indicators for the less rainy period, namely Paralucilia pseudolyrcea (Mello, 1969) (Diptera, Calliphoridae), Paralucilia nigrofacialis (Mello, 1969) (Diptera, Calliphoridae), and Eumesembrinella randa (Walker, 1849) (Diptera,Mesembrinellidae) while Chloroprocta idioidea (Robineau-Desvoidy, 1830) (Dipetra, Calliphoridae) was selected as an indicator species for the rainy period; no taxon was selected as an indicator of the intermediate period. Among decomposition stages, only fermentation and black putrefaction had indicator taxa, with Hemilucilia souzalopesi Mello, 1972 (Diptera, Calliphoridae and Chysomya putoria(Wiedemann, 1830) (Diptera, Calliphoridae), respectively. Clothes did not prevent the laying of eggs and became a kind of protection for immature stages. The clothed model presented a delay in decomposition compared to other studies developed in the Amazon region.

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Nós criamos massas de ovos dos tricópteros Phylloicus amazonas (n = 2) e Phylloicus elektoros (n = 7) coletadas no campo até a fase adulta. A mediana do tempo de desenvolvimento do primeiro instar larval ao adulto foi de 229 dias para P. amazonas e 275 dias para P. elektoros, incluindo o tempo de desenvolvimento pupal (mediana de 13.5 e 16 dias, respectivamente). Fragmentadores têm sido frequentemente usados em estudos relacionados ao processamento de matéria orgânica em ecossistemas aquáticos. As informações biológicas fornecidas neste estudo podem ser úteis para o planejamento de estudos experimentais em campo ou em condições de laboratório.(AU)

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We reared field-collected egg masses of the caddisflies Phylloicus amazonas (n = 2) and Phylloicus elektoros (n = 7) to adulthood. First instar larvae of both species hatched up to five days after field collection. Median development time from first larval instar to adult was 229 days for P. amazonas and 275 for P. elektoros, including the pupal development time (median of 13.5 and 16 days, respectively). Shredder organisms have been used frequently in studies related to organic matter processing in freshwater ecosystems. The biological information reported in here may be useful for the design of experimental studies in the field or under laboratory conditions.(AU)

Nós criamos massas de ovos dos tricópteros Phylloicus amazonas (n = 2) e Phylloicus elektoros (n = 7) coletadas no campo até a fase adulta. A mediana do tempo de desenvolvimento do primeiro instar larval ao adulto foi de 229 dias para P. amazonas e 275 dias para P. elektoros, incluindo o tempo de desenvolvimento pupal (mediana de 13.5 e 16 dias, respectivamente). Fragmentadores têm sido frequentemente usados em estudos relacionados ao processamento de matéria orgânica em ecossistemas aquáticos. As informações biológicas fornecidas neste estudo podem ser úteis para o planejamento de estudos experimentais em campo ou em condições de laboratório.(AU)

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In the dipteran genus Hermetia, only 6 of the 78 valid species have documented immature stages: H. albitarsis Fabricius, 1805, H. aurata Bellardi, 1859, H. concinna Williston, 1900, H. illucens (Linnaeus, 1758), H. panamensis Greene, 1940 and H. pulchra Weidemann, 1830. In particular, H. illucens stands out due to its reported applicability for forensic, medical and economic purposes. Here, we described the morphology of eggs and immature stages of this species, with a view to detecting differences between instars and in the pupal stage, which should eventually help properly identifying larval age. We utilized both optical and scanning electron microscopy tools. The eggs are elliptical and elongated, and color varies from cream white to yellowish. The larvae are apodal, hemichephalic and holopneustic, flattened dorso-ventrally and may be recognized by the head elongated, dorsal and ventral chaetotaxy of the cephalic capsule, thoracic and abdominal segments, and the morphology of the anterior and posterior spiracles. The pupae are adecticous and coarctate, tegument dark brown and pruinescence varying from brown to golden. The overall morphology across instars is similar, but marked variations were observed in the shape of the antennal articuli and the shape of the setae (first instar compared to the others). Our results supplement the biological information on Hermetia illucens and should aid the proper identification and aging of juveniles in the field, as a way to minimize errors in the calculation of the post-mortem interval.

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Climate change may affect the chemical composition of riparian leaf litter and, aquatic organisms and, consequently, leaf breakdown. We evaluated the effects of different scenarios combining increased temperature and carbon dioxide (CO2) on leaf detritus of Hevea spruceana (Benth) Müll. and decomposers (insect shredders and microorganisms). We hypothesized that simulated climate change (warming and elevated CO2) would: i) decrease leaf-litter quality, ii) decrease survival and leaf breakdown by shredders, and iii) increase microbial leaf breakdown and fungal biomass. We performed the experiment in four microcosm chambers that simulated air temperature and CO2 changes in relation to a real-time control tracking current conditions in Manaus, Amazonas, Brazil. The experiment lasted seven days. During the experiment mean air temperature and CO2 concentration ranged from 26.96 ± 0.98ºC and 537.86 ± 18.36 ppmv in the control to 31.75 ± 0.50ºC and 1636.96 ± 17.99 ppmv in the extreme chamber, respectively. However, phosphorus concentration in the leaf litter decreased with warming and elevated CO2. Leaf quality (percentage of carbon, nitrogen, phosphorus, cellulose and lignin) was not influenced by soil flooding. Fungal biomass and microbial leaf breakdown were positively influenced by temperature and CO2 increase and reached their highest values in the intermediate condition. Both total and shredder leaf breakdown, and shredder survival rate were similar among all climatic conditions. Thus, low leaf-litter quality due to climate change and higher leaf breakdown under intermediate conditions may indicate an increase of riparian metabolism due to temperature and CO2 increase, highlighting the risk (e.g., decreased productivity) of global warming for tropical streams.

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O objetivo do presente trabalho foi o estudo das infrapopulações e infracomunidades de parasitos de Hoplias malabaricus (Bloch, 1794) da represa Dr. João Penido, município de Juiz de Fora, MG. Entre novembro de 2004 e março de 2005 foram coletados 89 exemplares de H. malabaricus, dos quais 92,1% estavam parasitados por pelo menos uma espécie de parasito. Realizou-se o cálculo do fator de condição relativo (Kn) para cada peixe. Foram coletadas três espécies de nematóides: Contracaecum sp. e Eustrongylides ignotus, em estágio larvar e Procamallanus (Spirocamallanus) hilarii em estágio adulto. Contracaecum sp. foi a espécie dominante com maiores valores de abundância, prevalência, freqüência de dominância e dominância relativa média. Os parasitos de H. malabaricus apresentaram padrão típico de distribuição agregado. A comunidade de nematóides observada pode ser caracterizada como pouco diversa e com baixa uniformidade na distribuição. A prevalência e a abundância totais correlacionaram-se positivamente ao comprimento total, mesmo resultado obtido quando considerado a prevalência e a abundância de E. ignotus e Contracaecum sp.. Não foi observada influência do parasitismo no fator de condição relativo dos peixes. No presente trabalho a mudança da dieta durante a ontogênese de H. malabaricus e o ambiente do reservatório parecem ser os principais fatores que contribuíram para a estrutura comunitária de parasitos.(AU)

This paper aimed at studying parasite infrapopulations and infracommunities of Hoplias malabaricus (Bloch, 1794) from Doutor João Penido dam, in the city of Juiz de Fora, Minas Gerais state, Brazil. Between November 2004 and March 2005, we collected 89 specimens of Hoplias malabaricus, 92.1% of which were parasitized by at least one parasite species. Three nematode species were collected and identified as Contracaecum sp. and Eustrongylides ignotus, in larval stage, and Procamallanus (Spirocamallanus) hilari, in adult stage. Contracaecum sp. was the dominant species, presenting higher values of abundance, prevalence, frequency of dominance and mean relative dominance. The parasites found in H. malabaricus presented a typical aggregate distribution pattern. The nematode community we observed is characterized by little diversity and low distribution uniformity. Total prevalence and abundance were positively related with total length. This same result was attained when prevalence and abundance of E. ignotus and Contracaecum sp. were taken into consideration. Changes in diet during the ontogenesis of H. malabaricus and the dam environment seem to be, according to this study, the main factors contributing to the community structure of the parasites observed.(AU)

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O objetivo do presente trabalho foi o estudo das infrapopulações e infracomunidades de parasitos de Hoplias malabaricus (Bloch, 1794) da represa Dr. João Penido, município de Juiz de Fora, MG. Entre novembro de 2004 e março de 2005 foram coletados 89 exemplares de H. malabaricus, dos quais 92,1% estavam parasitados por pelo menos uma espécie de parasito. Realizou-se o cálculo do fator de condição relativo (Kn) para cada peixe. Foram coletadas três espécies de nematóides: Contracaecum sp. e Eustrongylides ignotus, em estágio larvar e Procamallanus (Spirocamallanus) hilarii em estágio adulto. Contracaecum sp. foi a espécie dominante com maiores valores de abundância, prevalência, freqüência de dominância e dominância relativa média. Os parasitos de H. malabaricus apresentaram padrão típico de distribuição agregado. A comunidade de nematóides observada pode ser caracterizada como pouco diversa e com baixa uniformidade na distribuição. A prevalência e a abundância totais correlacionaram-se positivamente ao comprimento total, mesmo resultado obtido quando considerado a prevalência e a abundância de E. ignotus e Contracaecum sp.. Não foi observada influência do parasitismo no fator de condição relativo dos peixes. No presente trabalho a mudança da dieta durante a ontogênese de H. malabaricus e o ambiente do reservatório parecem ser os principais fatores que contribuíram para a estrutura comunitária de parasitos.

This paper aimed at studying parasite infrapopulations and infracommunities of Hoplias malabaricus (Bloch, 1794) from Doutor João Penido dam, in the city of Juiz de Fora, Minas Gerais state, Brazil. Between November 2004 and March 2005, we collected 89 specimens of Hoplias malabaricus, 92.1% of which were parasitized by at least one parasite species. Three nematode species were collected and identified as Contracaecum sp. and Eustrongylides ignotus, in larval stage, and Procamallanus (Spirocamallanus) hilari, in adult stage. Contracaecum sp. was the dominant species, presenting higher values of abundance, prevalence, frequency of dominance and mean relative dominance. The parasites found in H. malabaricus presented a typical aggregate distribution pattern. The nematode community we observed is characterized by little diversity and low distribution uniformity. Total prevalence and abundance were positively related with total length. This same result was attained when prevalence and abundance of E. ignotus and Contracaecum sp. were taken into consideration. Changes in diet during the ontogenesis of H. malabaricus and the dam environment seem to be, according to this study, the main factors contributing to the community structure of the parasites observed.

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ABSTRACT Biomass is a fundamental measure for understanding the structure and functioning (e.g. fluxes of energy and nutrients in the food chain) of aquatic ecosystems. We aim to provide predictive models to estimate the biomass of Triplectides egleri Sattler, 1963, in a stream in Central Amazonia, based on body and case dimensions. We used body length, head-capsule width, interocular distance and case length and width to derive biomass estimations. Linear, exponential and power regression models were used to assess the relationship between biomass and body or case dimensions. All regression models used in the biomass estimation of T. egleri were significant. The best fit between biomass and body or case dimensions was obtained using the power model, followed by the exponential and linear models. Body length provided the best estimate of biomass. However, the dimensions of sclerotized structures (interocular distance and head-capsule width) also provided good biomass predictions, and may be useful in estimating biomass of preserved and/or damaged material. Case width was the dimension of the case that provided the best estimate of biomass. Despite the low relation, case width may be useful in studies that require low stress on individuals.

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The objective of this study was to analyze the colonization of Chironomidae (Diptera) larvae during the decomposition of Eichhornia azurea (Swartz) Kunth (Commelinales: Pontederiaceae) leaves in a lake in southeastern Brazil in two seasons of the year. The experiment was conducted from September to November 2007 and February to April 2008. In each period, 21 litter bags were used, each containing 10 g of dried leaves. Three bags were removed after 2, 5, 8, 12, 25, 45, and 65 days of colonization. The decomposition rate of the E. azurea leaves was rapid in both seasons, with no significant difference between them. The Chironomidae showed higher density than the other invertebrates. Goeldichironomus, Tonytarsus, and Corynoneura were the most abundant genera of Chironomidae. The invertebrate density increased during the experiment, differing within days but not between seasons. The faunal composition differed between the decomposition phases (initial and final), but did not differ between the seasons (dry and wet). The taxa Ablabesmyia, Caladomyia, Chironomus, Goeldichironomus, and Parachironomus were the most closely related to the final days of the experiment. Litter was the main food item found in the gut contents of the organisms of all the genera analyzed, both at the beginning and end of the decomposition. We believe that the feeding activity combined with the high larval density is an important factor contributing to the rapid decomposition of the E. azurea leaves. In conclusion, the succession process along the detritus chain of E. azurea was more important in structuring the assemblage of Chironomidae larvae than seasonal variations.

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