Potential use of Piper nigrum ethanol extract against pyrethroid-resistant Aedes aegypti larvae

Fractionation of Piper nigrum ethanol extract, biomonitored by assays on pyrethroid-resistant Aedes aegypti larvae yielded isolation of the larvicidal amides piperolein-A and piperine. Comparing LC50 values, the ethanol extract (0. 98 ppm) was the most toxic, followed by piperolein-A (1. 46ppm) and piperine (1. 53ppm).

Cocirculation of two dengue virus serotypes in individual and pooled samples of Aedes aegypti and Aedes albopictus larvae

INTRODUCTION: To detect dengue virus, eggs of Aedes sp were collected in the city of Belo Horizonte, Brazil, in 2007. METHODS: Egg samples were subsequently hatched and the larvae were tested for the presence of dengue virus RNA by RT-PCR. RESULTS: Among the Aedes aegypti larvae samples, 163 (37.4%) out of 435 were positive, including 32 (10.9%) of 293 individual larvae samples concomitantly positive for two serotypes. CONCLUSIONS: Virological surveillance detecting coinfected vectors in the field could represent an important strategy for understanding the numerous factors involved in the transmission and clinical presentation of dengue.

In vitro predatory activity of conidia of fungal isolates of the Duddingtonia flagrans on Angiostrongylus vasorum first-stage larvae

INTRODUCTION: Angiostrongylus vasorum is a nematode that parasitizes molluscs, dogs, and even man. METHODS: The objective was to evaluate the predatory activity of the conidia of two fungal isolates of Duddingtonia flagrans (AC001 and CG722) on first-stage larvae (L1) of A. vasorum in laboratory conditions. RESULTS: At the end of the experiment, there were significant reductions (p<0.01) of 74.5% and 63.2%, on average, in the A. vasorum L1 recovered in the AC001 and CG722 treatment conditions, respectively. CONCLUSIONS: The two isolates of fungi were efficient in the capture and destruction of A. vasorum L1.

Larvicidal effects of endophytic and basidiomycete fungus extracts on Aedes and Anopheles larvae (Diptera, Culicidae)

Introduction In vitro bioassays were performed to access the larvicidal activity of crude extracts from the endophytic fungus Pestalotiopsis virgulata (Melanconiales, Amphisphaeriaceae) and the saprophytic fungus Pycnoporus sanguineus (Basidiomycetes, Polyporaceae) against the mosquitoes Aedes aegypti and Anopheles nuneztovari. Methods The extracts were tested at concentrations of 100, 200, 300, 400 and 500ppm. Ethyl acetate mycelia (EAM) extracts and liquid culture media (LCM) from Pe. virgulata and Py. sanguineus were tested against third instar larvae of Ae. aegypti and An. nuneztovari. Results The larvicidal activity of the EAM extracts from Pe. virgulata against Ae. aegypti had an LC50=101.8ppm, and the extract from the basidiomycete fungus Py. sanguineus had an LC50=156.8ppm against the Ae. aegypti larvae. The Pe. virgulata extract had an LC50=16.3ppm against the An. nuneztovari larvae, and the Py. sanguineus extract had an LC50=87.2ppm against these larvae. Conclusions These results highlight the larvicidal effect of EAM extracts from the endophyte Pe. virgulata against the two larval mosquitoes tested. Thus, Pe. virgulata and Py. sanguineus have the potential for the production of bioactive substances against larvae of these two tropical disease vectors, with An. nuneztovari being more susceptible to these extracts.

Occurrence of potentially pathogenic Vibrio in oysters (Crassostrea gigas) and waters from bivalve mollusk cultivations in the South Bay of Santa Catarina

Introduction This research aimed to identify and quantify potentially pathogenic Vibrio from different cultivations of bivalve shellfish in the State of Santa Catarina, Brazil, and water regions in the South Bay, as well as correlate the incidence of these microorganisms with the physicochemical parameters of marine waters. Methods Between October 2008 and March 2009, 60 oyster and seawater samples were collected from six regions of bivalve mollusk cultivation, and these samples were submitted for Vibrio counts. Results Twenty-nine (48.3%) oyster samples were revealed to be contaminated with one or more Vibrio species. The Vibrio parahaemolyticus and Vibrio vulnificus counts in the samples ranged from < 0.5 log10 Most Probable Number (MPN) g–1 to 2.3 log10 MPN g–1 oyster and from < 0.5 log10 MPN g–1 to 2.1 log10 MPN g–1 oyster, respectively. Of the 60 seawater samples analyzed, 44 (73.3%) showed signs of contamination with one or more vibrio species. The counts of V. parahaemolyticus and V. vulnificus in the samples ranged from < 0.3 log10 MPN·100mL–1 to 1.7 log10MPN·100mL–1 seawater and from < 0.3 log10 MPN·100mL–1 to 2.0 log10 MPN·100mL–1 seawater, respectively. A positive correlation between V. vulnificus counts and the seawater temperature as well as a negative correlation between the V. parahaemolyticus counts and salinity were observed. Conclusions The results suggest the need to implement strategies to prevent vibrio diseases from being transmitted by the consumption of contaminated bivalve shellfish.

Ontogeny of swimming capacity in plaice (Pleuronectes platessa) larvae

Little is known regarding the swimming ability of the larvae of European plaice (Pleuronectes platessa) in relation to changes in total length (TL), dry weight (DW) and developmental stage, which is surprising given the importance of transport processes to the recruitment dynamics of this species in the North Sea and elsewhere. We investigated ontogenetic changes in the critical swimming speed (Ucrit) of plaice from hatching to the onset of metamorphosis (50 days post-hatch, dph) at 8 °C. The mean (±SD) TL and DW growth rates were 1.59 ± 0.81 and 7.7 ± 0.35 % d−1, respectively. Larvae were unable to swim at against a minimum current speed of <0.5 cm s−1 until 10 dph (7 mm TL), after which Ucrit significantly increased with increasing TL until the onset of metamorphosis and subsequent settlement. Mean (±SD) Ucrit was 0.38(0.35), 1.59(0.54), 2.27(0.49) and 2.99(0.37) cm s−1 for stage I (6.61 ± 2.64 mm TL), stage II (7.75 ± 0.60 mm TL), stage III (9.10 ± 1.00 mm TL) and stage IV (11.59 ± 0.85 mm TL) larvae, respectively. Larval TL, DW, DNA content, RNA content and Ucrit significantly increased, whereas sRD significantly declined as larvae developed from stage I to V. Although inter-individual differences in Ucrit (coefficient of variation, CV = 33 %) were as large as those in biochemical and morphological condition (CV’s of 21–42 %), differences in Ucrit were not significantly related to those in nutritional condition and larvae with lower DNA/DW had also better swimming abilities. These estimates should be useful to ongoing efforts to create individual- based models of the transport, foraging and growth of plaice larvae in the North Sea.

Effects of ocean acidification on the swimming ability, development and biochemical responses of sand smelt larvae

Ocean acidification, recognized as a major threat to marine ecosystems, has developed into one of the fastest growing fields of research in marine sciences. Several studies on fish larval stages point to abnormal behaviours, malformations and increased mortality rates as a result of exposure to increased levels of CO2. However, other studies fail to recognize any consequence, suggesting species-specific sensitivity to increased levels of CO2, highlighting the need of further research. In this study we investigated the effects of exposure to elevated pCO2 on behaviour, development, oxidative stress and energy metabolism of sand smelt larvae, Atherina presbyter. Larvae were caught at Arrábida Marine Park (Portugal) and exposed to different pCO2 levels (control: ~600μatm, pH=8.03; medium: ~1000μatm, pH=7.85; high: ~1800μatm, pH=7.64) up to 15days, after which critical swimming speed (Ucrit), morphometric traits and biochemical biomarkers were determined. Measured biomarkers were related with: 1) oxidative stress - superoxide dismutase and catalase enzyme activities, levels of lipid peroxidation and DNA damage, and levels of superoxide anion production; 2) energy metabolism - total carbohydrate levels, electron transport system activity, lactate dehydrogenase and isocitrate dehydrogenase enzyme activities. Swimming speed was not affected by treatment, but exposure to increasing levels of pCO2 leads to higher energetic costs and morphometric changes, with larger larvae in high pCO2 treatment and smaller larvae in medium pCO2 treatment. The efficient antioxidant response capacity and increase in energetic metabolism only registered at the medium pCO2 treatment may indicate that at higher pCO2 levels the capacity of larvae to restore their internal balance can be impaired. Our findings illustrate the need of using multiple approaches to explore the consequences of future pCO2 levels on organisms.

Description of microsporidia in simulids: molecular and morphological characterization of microsporidia in the larvae of Simulium pertinax Kollar (Diptera: Simuliidae)

IntroductionMicrosporidia constitute the most common black fly pathogens, although the species' diversity, seasonal occurrence and transmission mechanisms remain poorly understood. Infections by this agent are often chronic and non-lethal, but they can cause reduced fecundity and decreased longevity. The objective of this study was to identify microsporidia infecting Simulium (Chirostilbia) pertinax (Kollar, 1832) larvae from Caraguatatuba, State of São Paulo, Brazil, by molecular and morphological characterization.MethodsLarvae were collected at a single point in a stream in a rural area of the city and were kept under artificial aeration until analysis. Polydispyrenia spp. infection was characterized by the presence of at least 32 mononuclear spores measuring 6.9 ± 1.0 × 5.0 ± 0.7µm in persistent sporophorous vesicles. Similarly, Amblyospora spp. were characterized by the presence of eight uninucleate spores measuring 4.5 × 3.5µm in sporophorous vesicles.ResultsThe molecular analysis confirmed the presence of microsporidian DNA in the 8 samples (prevalence of 0.51%). Six samples (Brazilian larvae) were related to Polydispyrenia simulii and Caudospora palustris reference sequences but in separate clusters. One sample was clustered with Amblyospora spp. Edhazardia aedis was the positive control taxon.ConclusionsSamples identified as Polydispyrenia spp. and Amblyospora spp. were grouped with P. simulii and Amblyospora spp., respectively, corroborating previous results. However, the 16S gene tree showed a considerable distance between the black fly-infecting Amblyospora spp. and the mosquito-infecting spp. This distance suggests that these two groups are not congeneric. Additional genomic region evaluation is necessary to obtain a coherent phylogeny for this group.

Comparative study of cultivation of feces in vermiculite or charcoal to obtain larvae of Strongyloides venezuelensis

IntroductionWe compared feces culturing in charcoal or vermiculite to obtain Strongyloides venezuelensis larvae.MethodsFeces (5g) from infected rats was mixed with vermiculite (10g) or coal (10g) in plastic cups and incubated at 28°C for 48h. Larvae were recovered using Baermann-Moraes method.ResultsSignificantly higher number of positive larval cultures were recovered from vermiculite than from charcoal (15/17 and 4/17, respectively; p < 0.001; 990.6 ± 307.5 and 215 ± 78.1 larvae, p = 0.027).ConclusionsVermiculite yields more larvae and provides cleaner pellets, improving larvae identification and facilitating their use for other purposes.

The role of Hedgehog signaling during zebrafish larvae fin fold regeneration

Several studies have demonstrated that although the structure of the adult and larval zebrafish caudal fin is different, there are similarities at the cellular and molecular level that turn larval zebrafish fin fold a useful model to study the basic principles of regeneration. In this process, while the essential role for Hedgehog (Hh) signaling is well established in the adult zebrafish caudal fin system, its involvement in juvenile tissue regeneration is still unknown. The aim of this Master thesis was therefore to evaluate the contribution of the Hh signaling pathway to the larval zebrafish fin fold regeneration process. Accordingly, we analyzed the expression of several Hh signaling components through in situ hybridization. Here, we showed that several of these genes are effectively expressed in the larval regenerating fin tissue, suggesting a role for Hh signaling also during larval regeneration. However, divergence in the regulation of few Hh signaling components appears to exist between the adult and larval zebrafish fin regeneration processes. Nevertheless, similarly to adult caudal fin regeneration, when Hh signaling was blocked, by using cyclopamine, the larval fin fold regenerative outgrowth is severely impaired. Since larval zebrafish fin fold is ciliated, and primary cilia are closely related to Hh signaling regulation in vertebrate systems, we further addressed the role of primary cilia during larval fin fold regeneration process. To this end, we used the zebrafish iguana mutant, in which primary cilia are not formed, to study the modulation of Hh signaling expression during larval fin fold regeneration in the absence of primary cilia. Here, we found that several genes were expressed with a delay, coincident with the delay in the mutant fin fold regeneration observed in previous work. We show that Hh signaling in the fin fold is crucial to promote cell proliferation. When Hh signaling is blocked using cyclopamine there is a strong blockage of cell proliferation and regeneration is also blocked. Surprisingly, in iguana mutants where Hh signaling is impaired but not totally blocked, cell proliferation is not detected but regeneration still occurs. This raises the question about the requirement of cell proliferation in larvae fin fold regeneration. By blocking the cell cycle using aphidicolin we demonstrate that cell proliferation is not necessary for zebrafish larvae fin fold regeneration.

On occurrence, habitat specificity and natural history of adult tiger beetles (Coleoptera: Carabidae: Cicindelinae) near Manaus, Central Amazonia, and key to the larvae of tiger beetle genera

Over a seven year period from 1991 to 1997, 22 species of tiger beetles, representing nine genera, were recorded near Manaus, Brazil. In the Whitewaterfloodplains along the Rio Solimões-Amazonas (Ilha de Marchantaria), three diurnal species inhabit inundation forests and six species (two diurnal, four nocturnal) live in open areas. Data on their natural history and adaptation to living conditions in floodplains are presented. Fifteen species were located on non-flooded uplands (Reserva Florestal A. Ducke). Five diurnal species inhabit the forest floor, two species are canopy dwellers, and eight species (seven diurnal, one nocturnal) live in open areas on whitesand or laterite. Only one species, Pentacomia lacordairei, was found in both floodplain and upland forests. A key to the larvae of tiger beetle genera located near Manaus is presented.

Feeding of the Brycon cephalus, Triportheus elongatus and Semaprochilodus insignis (osteichthyes, characiformes) larvae in Solimões/Amazonas River and floodplain areas.

Information on larval fish feeding is essential for understanding their trophic relations, including the management in conditions totally or partially controlled by humans. An experiment was designed to evaluate the larval diets of three commercially important species. Four varzea-lakes and the adjacent river were sampled with bongo and hand nets from January 1993 to November 1995. Larval diets were evaluated by length-classes and capture sites, and were tested by two factor ANOVA. The larvae were feeding in all habitats, except in the flooded forests. The three species had different diets, which varied with their length and lake. The rotifers were the main initial food item of the three species, replaced by fish larvae in Brycon cephalus, cladocerans in Triportheus elongatus and detritus in Semaprochilodus insignis. The increase of the ingestion limit, as the larvae grew, was higher than the increase in the consumed prey size for the three species.

Screening of plants found in the State of Amazonas, Brazil for activity against Aedes aegypti larvae

Ethanol, methanol and water extracts representing mostly native plant species found in the Amazon region were prepared, respectively, by maceration, continuous liquid-solid extraction and infusion, followed by evaporation and freeze-drying. The freeze-dried extracts were tested for lethality toward Aedes aegypti larvae at test concentrations of 500 mg / mL. In general, methanol extracts exhibited the greatest larvicidal activity. The following 7 methanol extracts of (the parts of) the indicated plant species were the most active, resulting in 100% mortality in A. aegypti larvae: Tapura amazonica Poepp. (root), Piper aduncum L. (leaf and root), P. tuberculatum Jacq. (leaf, fruit and branch). and Simaba polyphylla (Cavalcante) W.W. Thomas (branch).

Developmental morphology of mouthparts and foregut of the larvae and postlarvae of Lepidophthalmus siriboia Felder & Rodrigues, 1993 (Decapoda: Callianassidae)

In this study, the gross morphology of the mouthparts and foregut of the ghost shrimp Lepidophthalmus siriboia were investigated from larvae and postlarvae reared in the laboratory. The mouthparts (maxillae and maxillipeds) of the zoeae have a reduced number of setae and spines (or is absent in some individuals), and the foregut, under developed, have few minute setae in the cardiac and pyloric chambers. In contrast, after the metamorphosis into megalopa stage, all feeding appendages have many setae and, the foregut shows a well-developed gastric mill with strong lateral teeth. In the juvenile stage occurs an increase of setae and spines in the mouthparts and the foregut becomes more specialized. These observations strongly suggest that a lecithotrophic development occurs during all zoeal stages but the megalopa and juvenile stages are feeding animals. The functional morphology of the feeding structures of L. siriboia and other decapods will be briefly discussed.

The morphology of the foregut of larvae and postlarva of Sesarma curacaoense De Man, 1892: a species with facultative lecithotrophy during larval development

Previous study on the resistance of larvae of Sesarma curacaoense submitted to starvation has revealed a facultative lecithotrophy during zoeal stages, but megalopa and first juvenile stages are exclusively feeding stages. In the present study, the gross morphology and fine structure of the foregut of S. curacaoense were investigated during larval, megalopa and first juvenile stages. The foregut of the zoea I show specific setae and a filter press apparently functional. The foregut undergoes changes in the zoea II (last larval stage) with increment of setae number, mainly on the cardiopyloric valve and complexity of the filter press. After metamorphosis to megalopa stage the foregut become rather complex, with a gastric mill supporting a medial and two lateral teeth well-developed. The foregut of the first juvenile is more specialized compared to the previous stage, showing similar characteristics of the decapod adults. These results provide further evidence of facultative lecithotrophic development in the larvae of S. curacaoense.