Mineralogical and geochemical influences on sediment color of Amazon wetlands analyzed by visible spectrophotometry

Based on sedimentological and geochemical data, this work relates spectrophotometric measurements with sediment composition and its application in palaeoecological studies of Amazon wetlands. The CIELAB values are directly related to mineralogical and chemical composition, mostly involving quartz, iron oxyhydroxides and sulfides (e.g. pyrite), and total organic carbon. Total organic carbon contents between 0.4-1%, 1-2%, 3-5% and 15-40% were related to L* (lightness) data of 27, 26-15, 7-10 and 7 or less, respectively. The CIELAB values of a deposit in Marabá, Pará, were proportional to variations in quartz and total organic carbon contents, but changes in zones of similar color, mainly in the +a* (red) and +b* (yellow) values of deposits in Calçoene, Amapá and Soure, Pará, indicate a close relationship between total organic carbon content and iron oxyhydroxides and sulfides. Furthermore, the Q7/4 diagram (ratio between the % re?ectance value at 700 nm to that at 400 nm, coupled with L*) indicated iron-rich sediments in the bioturbated mud facies of the Amapá deposit, bioturbated mud and bioturbated sand facies of Soure deposit, and cross-laminated sand and massive sand facies of the Marabá core. Also, organic-rich sediments were found in the bioturbated mud facies of the Amapá deposit, lenticular heterolithic and bioturbated mud facies of the Soure deposit, and laminated mud and peat facies of the Marabá deposit. At the Marabá site, the data suggest an autochthonous influence with peat formation. The coastal wetland sites at Marajó and Amapá represent the development of a typical tidal flat setting with sulfide and iron oxyhydroxides formation during alternated flooding and drying.

Characterization of dry-stack interlocking compressed earth blocks

Earth has been a traditional building material to construct houses in Africa. One of the most common techniques is the use of sun dried or kiln fired adobe bricks with mud mortar. Fired bricks are the main cause for deforestation in countries like Malawi. Although this technique is low-cost, the bricks vary largely in shape, strength and durability. This leads to weak houses which suffer considerable damage during floods and seismic events. One solution is the use of dry-stack masonry with stabilized interlocking compressed earth blocks (ICEB). This technology has the potential of substituting the current bricks by a more sustainable kind of block. This study was made in the context of the HiLoTec project, which focuses on houses in rural areas of developing countries. For this study, Malawi was chosen for a case study. This paper presents the experimental results of tests made with dry-stack ICEBs. Soil samples from Malawi were taken and studied. Since the experimental campaign could not be carried out in Malawi, a homogenization process of Portuguese soil was made to produce ICEBs at the University of Minho, Portugal. Then, the compression and tensile strength of the materials was determined via small cylinder samples. Subsequently, the compression and flexural strength of units were determined. Finally, tests to determine the compressive strength of both prisms and masonry wallets and to determine the initial shear strength of the dry interfaces were carried out. This work provides valuable data for low-cost eco-efficient housing

Optimal behavior of responsive residential demand considering hybrid phase change materials

Due to communication and technology developments, residential consumers are enabled to participate in Demand Response Programs (DRPs), control their consumption and decrease their cost by using Household Energy Management (HEM) systems. On the other hand, capability of energy storage systems to improve the energy efficiency causes that employing Phase Change Materials (PCM) as thermal storage systems to be widely addressed in the building applications. In this paper, an operational model of HEM system considering the incorporation of more than one type of PCM in plastering mortars (hybrid PCM) is proposed not only to minimize the customerâ s cost in different DRPs but also to guaranty the habitantsâ  satisfaction. Moreover, the proposed model ensures the technical and economic limits of batteries and electrical appliances. Different case studies indicate that implementation of hybrid PCM in the buildings can meaningfully affect the operational pattern of HEM systems in different DRPs. The results reveal that the customerâ s electricity cost can be reduced up to 48% by utilizing the proposed model.

Desenvolvendo a qualidade em parcerias: a voz de um grupo de educadoras

Tese de Doutoramento em Estudos da Criança (Especialidade de Metodologia e Supervisão em Educação de Infância)

Evaluation of fish pots as a feasible fishing method in Irish waters, with specific reference to the physiological effects of common and alternate pots on the lesser spotted dogfish (Scyliorhinus canicula).

Finfish pots have emerged as a “responsible” gear, when used in combination with conservational and technical measures to sustain fisheries. Previous trials in Irish waters have offered no published reported data and so three designs tested in the current study provide new information on this gear. The most successful traps in terms of fish catch were rigid steel framed rectangular pots used to target Conger eel. Although commercial yield was low (0.2 per trap haul), potential existed for a viable pot fishery. Deployment and storage of Norwegian floating pots was conducted with relative ease but performance in the water was poor resulting in loss of gear. Catch returns were notable even though effort was restricted as mega-faunal by-catch was a problem, which lead to ending this trial. From these initial trials it was evident that catch rates were low compared to established Norwegian fisheries (3.6 cod per pot), which resulted in the utilisation of pots, already established in the crustacean fishery, to find species readily accessible to pot capture. Although fished and designed differently, these gears provided an opportunity to establish the benefits of pot fishing to fish quality and to determine the effects on by-catch. The fishing effects of three catching methods (pots, angling and trawl) and the effects of air exposure on the physiological status of a common by-catch, the lesser spotted dogfish Scyliorhinus canícula (L.) were examined using a range of physiological biomarkers (plasma catecholamine, glucose, lactate, muscle pH and muscle lactate). Physiological responses of fish to an emersion stress regime resulted in a significant metabolic disturbance in groups, but may not have weakened the overall health of these fish, as signified in the revival of some metabolites. Plasma glucose and lactate concentrations did not however recovery to baseline levels indicating that to achieve an accurate profile, responses should be determined by a suite of biomarkers. Responses did not demonstrate that samples from the pots were significantly less stressed than for the other two methods; angling and trawling, which are in contrast to many other studies. Employment of finfish potting therefore in Irish waters needs further consideration before further promotion as a more responsible method to supplement or replace established techniques.

Fatôres que afetam a determinação da vitamina C na goiaba (Psidium guajava L.)

In the present paper the authors deal with the content of ascorbic acid in guavas (Psidium guajava L.) and the methods of sampling used. Ascorbic acid was determined directly in the photoeletric colorimeter (EEL), after extraction with a 4 per cent solution of oxalic acid. Guavas from various parts of State of S.Paulo were used and the general mean found was around 100 mgm of ascorbic acid per 100 gm fresh weight of the material used for extraction. It was found that there is great variation in the ascorbic acid content according to the condition of the fruit: Ascorbic acid Condition content in Mean mgm/100 gm Green and hard 93,36 - 119,54 102,43 Small green 57,34 - 92,30 83,40 Firm ripe 71,28 - 115,98 90,32 Overripe 63,22 - 85,98 77,36 Of the diferent parts of the fruit, the skin has the highest content; the pulp between the skin and the parts containing the seeds, the "inner pulp" contains little and finallw the central parts, formed by the pulp between seeds, the "inter pulp" a engligible amount. The proportion of ascorbic acid found in the skin, inner pulp and inter pulp may be as high as 1.6: 1: 0. Furthermore, the section near the peduncule and the sepals are richer than equatorial crossections. It was proved that the amount and intensity of sun-light is at least one important factant factor determining differences in the ascorbic acid content of the fruit, which is higer in the parts which have received more light. A sharp decrease was found in the vitamin C content of ripe fruite stored in a home refrigerator. The periods of the preservation were 12-24-48-96 hours and the decrease of the ascorbic acid content m per cent was 23.4 - 42.0 - 66.8 - 76.4 of the initial content of 144.28 mgm/100 gm. The following five different methods of sampling in the determination of the amount of vitamin C were tested, with extraction in a Waring blendor: 1) whole fruit; 2,) sample taken form fruits cut into many small pieces; 3) half of a fruit divided by a crossection at equal distance from both ends; 4) half of fruit divided lenghtwise; 5) a transversal slice of about 1 cm. It was found that the two first methods geve the most reliable results.

First records of Freshwater Bivalves of Ilha Grande National Park, Paraná, Brazil

The Ilha Grande National Park, Paraná, Brazil, is located in the Upper Paraná River and has characteristics typical of a floodplains. This protected area includes lagoons connected and disconnected to the Paraná River, although the latter also connect during periods of high water level, thus composing a heterogeneous group of lacustrine environments. The enormous potential the flora and fauna diversities are still little known to the region, as can be seen through benthic invertebrates, inclunding bivalves mollusks. The granulometric composition of these floodplain lagoons was formed mainly by mud and very fine sand. Furthermore, organic matter composition was predominantly of fine particulate. The other abiotic factors differed from lagoons located within the island of the park to those located in the left margin of Paraná River. The results demonstrated the importance of abiotic factors such as the physical composition of granulometric texture, organic matter and macrophyte banks, to the establishment of bivalves in these floodplain lagoons. We recorded bivalves of Pisidium (native), Diplodon (native), and Corbicula (invasive). The highest values of Diplodon sp. density were observed at São João/C lake, for Pisidium sterkianum (Pilsbry, 1897) at São João/M lake, and to Jatobá/C lagoon with high density of invasive species Corbicula fluminea (Müller, 1774). This study to obtain conduct the first records of freshwater bivalves in floodplains lagoon in the Ilha Grande National Park, and provides contributions to better understanding the ecology of these mollusks. The recording of native species in the region of Upper Paraná River floodplain after a lomg period without new records, demonstrated the importance of protecting the lagoons of the Ilha Grande National Park as they can be a possible refuge to some species of native freshwater bivalves.

Biologia do saguirú (Characidae, Curimatinae)

In Brazil all the fishes belonging to the sub-family Curimatinae are called « saguirú ». The present work gives a biological study of the Curimatus elegans Steind., a small fish without any economical importance, which is to be found along the whole brazilian coast, down till Paraguay. The specimens utilized for the present study come from Fortaleza (Ceará, north-eastern Brazil). The C. elegans is « ilyophagus », that means, it feeds itself exclusively with those organic materials to be found in mud, specially with microscopical algae. The intestines are very extent, some of them measuring about 9 to 11 times body's length. Studies have been made about growth and age of the C. elegans; the biggest sizes found were of 153 mm. for females and 88 mm. for males. The C. elegans shows developed sexual glands during a long period (April to September). The movements of the spermatozoa, in contact with water is of 40 to 50 seconds of intense movements, ceasing after 70 to 100 seconds. In contact with 0.5% NaCl-solution spermatozoa show a big increase in movements-time, that can last till about 25 minutes. The eggs' diameter measures 0.70 to 0.73 mm., mature and hydrated it attains 0.93 to 1,00 mm. There is a certain correlation between the size of the body and the quantity of eggs. Big specimens can produce a total of 200.000 eggs. The average quantity contained in 1 gr. and 1 cc. is 6018 and 6229 eggs, respectively. Maturity and spawning in laboratory has been obtained due to injections of suspension of fish-hypophysis. Three or four hours after the injection, fishes show more movement and evident signs of excitation, proceeding spawning after 5 to 6 hours. Males, persecuting females, describe successive circles (merry-go-round) - carroussel), swimming side by side with females up to water's surface, where sexual products are start beating dry, for there is no blood yet. Circulation-scheme is to be found on fig. 4 and 5. The swim-bladder and the stomach are but delineated; the intestine is formed by a cylindric tube, all closed. At the place, where later on there will open the mouth, we find a group of ciliary hairs that produce a liquid current, very evident by the semi-circle formed by attached solid particles. After 36 hours, opening of the mouth and formation of the gill slits begin. At the age of 90 hours (4 mm.) the larvas swim well and start to feed themselves; the digestive tube is now all open and the swimbladder works already. During the first days of life, larvas have an adhesive organ situated at their frontal region (fig. 7) in form of a crescent, by means of which they hang to surrounding vegetation (fig. 6). When the larva begins to swim and to feed itself and its yolk are having been absorbed. the adhesive organ retracts and disappears. While larvas and alevins feed themselves with plancton, they have small eye-teeth, which disappear,. when fishes become « ilyophagus ». There exist too, during their life as larvas, pharyngeal-teeth. The lateral line appears in the larva after 16 to 18 days; more or less at the same time all fins are completely developed. Shortly after, first scales appear (20 to 23 days). Evolution of intestines twisting followed (fig. 9). Larvas show at different parts of their bodies small of organs excretory functions, that are constituted by bottons in serial disposition, every one with an excretory canal that opens towards the outside. These formations disappear suddenly when larvas attain their phase of alevin. The existence of a great number of said formations at the caudal fin (fig. 12) is of great interest. In our experiences of breeding we have employed several thousands of C. elegans larvas in different environs and we made conditions of surrounding change (illumination), depth of water, temperature, presence of sand at bottom of aquariums and without sand, food). In this way we could compare the results obtained, estimate the action of each factor for the realisation of a good bring-up of larvas.

Distribuição geográfica da fauna e flora da Baía de Guanabara

The author studied, the horizontal and vertical distribution of most common part of the flora and fauna of the bay of Guanabara at Rio de Janeiro. In this paper the eulittoral, poly, meso and oligohaline regions were localised and studied; and the first chart of its distribution was presented (fig. 2). The salinity of superficial waters was established through determinations based on 30 trips inside the buy for collecting biological materials. Some often 409 determinations which were previous reported together with the present ones served for the eleboration of a salinity map of the bay of Guanabara (fig. 1). This map of fig. 2 shows the geographic locations of the water regions. EULITTORAL WATER REGIME — Fig. 3 shows the diagram scheme of fauna and flora of this regime. Sea water salinity 34/1.000, density mean 1.027, transparent greenish waters, sea coast with moderate bursting waves. Limpid sea shore with white sand, gneiss with the big barnacle Tetraclita squamosa var. stalactifera (Lam. Pilsbry. Vertical distributions: barna¬cles layers with a green region in which are present the oyster Ostrea pa-rasitica L., the barnacles Tetraclita, Chthamalus, Balanus tintinnabulum var. tintinnabulum (L.) e var. antillensis Pilsbry in connection with several mollusca and the sea beatle Isopoda Lygia sp. Covered by water and exposed to air by the tidal ritms, there is a stratum of brown animals that is the layer of mussels Mytilus perna L., with others brown and chestnut animals : the Crustacea Pachygrapsus, the little crab Porcellana sp., the stone crab Me-nippe nodifrons Stimpson, the sea stars Echinaster brasiliensis (Mull. & Tr.), Astropecten sp. and the sea anemones Actinia sp. Underneath and never visible there is a subtidal region with green tubular algae of genus Codium and amidst its bunches the sea urchin Lycthchinus variegatus (Agass.) walks and more deeply there are numerous sand-dollars Encope emarginata (Leske). The microplancton of this regime is Ceratiumplancton. POLYHALINE WATER REGIMB — Water almost sea water, but directly influenced by continental lands, with rock salts dissolved and in suspension. Salinity: 33 to 32/1.000. This waters endure the actions of the popular nicknamed «water of the hill» (as the waters of mesohaline and oligohaline regimes), becoming suddenly reddish during several hours. That pheno¬menon returns several times in the year and come with great mortality of fishes. In these waters, according to Dr. J. G. FARIA there are species of Protozoa : Peridinea, the Glenoidinium trochoideum St., followed by its satellites which he thinks that they are able to secret toxical substances which can slaughter some species of fishes. In these «waters of the hill» was found a species of Copepoda the Charlesia darwini. In August 1946 the west shore of the Guanabara was plenty of killed fishes occupying a area of 8 feet large by 3 nautical miles of lenght. The enclosure for catching fishes in the rivers mouthes presents in these periods mass dead fishes. The phenomenon of «waters of the hill» appears with the first rains after a period of long dryness. MESOHALINE WATER REGIME — Fig. 4 shows the the diagramm scheme. Salt or brackish water from 30 to 17/1.000 salinity, sometimes until 10/1.000. Turbid waters with mud in suspension, chestnut, claveyous waters; shore dirty black mud without waving bursting; the waters are warmer and shorner than those of the polihaline regime. Mangrove shore with the mangrove trees : Rhizophora mangle L., Avicennia sp., Laguncularia sp., and the »cotton tree of sea» Hibiscus sp. Fauna: the great land crab «guaimú» Cardisoma guanhumi Latr., ashore in dry firm land. There is the real land crab Ucides cordatus (L.) in wetting mud and in neigh¬ bourhood of the burrows of the fiddler-crabs of genus Uca. On stones and in the roots of the Rhizophora inhabits the brightly colored mangrove-tree-crab («aratu» Portuguese nickname) Goniopsis cruentata (Latreille) and the sparingly the big oyster Ostrea rhizophorae Guild. Lower is the region of barnacles Balanus amphitrite var. communis Darwin and var. niveus Darwin; Balanus tintinnabulum var. tintinnabulum (L.) doesn't grow in this brackish water; lower is the region of Pelecipoda with prepollency of Venus and Cytherea shell-fishes and the Panopeus mud crab; there are the sea lettuce Ulva and the Gastreropod Cerithium. The Paguridae Clibanarius which lives in the empty shells of Gasteropod molluscs, and the sessile ascidians Tethium plicatum (Lesuer) appears in some seasons. In the bottom there is a black argillous mud where the «one landed shrimps» Alpheus sp. is hidden. OLIGOHALINE WATER REGIME — The salinity is lower than 10/1.000. average 8/1.000. There are no barnacles and no sea-beetles Isopods of genus Lygia; on the hay of the shore there are several graminea. This brackish water pervades by mouthes of rivers and penetrates until about 3 kilometers river above. While there is some salt dissolved in water, there are some mud crabs of the genus Uca, Sesarma, Metasesarma and Chasmagnatus. The presence of floating green plants coming from the rivers in the waters of a region indicated the oligohaline waters, with low salt content because when the average of NaCl increases above 8/1.000 these plants die and become rusty colored.

Miocardite no macaco Cebus após inoculações repetidas com Schizotrypanum cruzi

Transmission of Chagas disease is realized through contamination of ocular conjunctiva, mucosa or skin with infected dejections eliminated by the insect vectors of Schizotrypanum cruzi (Triatoma infestans, Panstrongylus megistus and Rhodnius prolixus). The triatomid bugs live in holes and craks in the walls, in beds, behind trunks, etc. Found in primitive mud huts covered with thatched roofs, and so the human dwellers have many chances to contract the disease, reinfections being reasonably more to expect than a single inoculation. Experimental work reproducing those natural conditions is welcomed as some important features in the pathologic picture of the disease such as the extensive myocardial fibrosis seen in chronic cases are still incompletely known. Microscopic changes were studied in the heart muscle of seven Cebus monkeys infected by S. cruzi. This animal survives the acute stage of the disease and so is particularly suited to experiments of long duration in which several inoculations of S. cruzi are performed. Three different strains of S. cruzi isolated from acute cases of Chagas' disease were employed. One monkey was injected in the skin with infected blood and necropsied after 252 days. Two monkeys were three times, and one, eight times infected in skin, one of them with contaminated blood, and two with contaminated blood and dejections from infected bugs. The necropsies were performed after 35, 95 and 149 days. One monkey was three times inoculated through the intact ocular conjunctiva (one time with infected blood, two times with dejections from infected bugs), and one time through the wounded buccal mucosa, and necropsied after 134 days. Another monkey was six times inoculated, four times through the intact ocular conjunctiva (one time with contaminated blood, three times with dejections from infected bugs) and two times injected in the skin with infected blood, and necropsied after 157 days. Finally, another monkey was nine times inoculated, four times through the intact ocular conjunctiva (one time with infected blood, and three times with dejections from infected bugs), and five times injected in the skin (four times with contaminated blood, and one time with dejections from infected bugs), and necropsied after 233 days. The microscopic picture was uniform presenting, however, considerable individual variations, and was represented by diffuse interstitial myocarditis, frequently more (marked in the right ventricle base of the heart), accompanied by lymphatic stasis. The infiltration consists of macrophages, plasma cells and lymphocytes, the cellular reaction having sometimes a perivascular distribution, involving the auriculo-ventricular system of conduction, endocardium, epicardium and cardiac sympathetic gangliae. The loss of cardiac muscle fibers was always minimal. Leishmanial forms of S. cruzi in myocardial fibers are scanty and, in two cases, absent. Fatty necrosis in the epicardium was noted in two cases. Obliterative changes of medium-sized branches of coronary arteries (hypersensitivity reaction?) and multiple infarcts of the myocardium was found in one instance. The diffuse myocarditis induced by S. cruzi in several species of monkeys of the genus Cebus observed after 233 days (several inoculations) and 252 days (single inoculation) is not associated with disseminated fibrosis such as is reported in chronic cases of Chagas' disease. Definite capacity of reversion is another characteristic of the interstitial myocarditis observed in the series of Cebus monkeys here studied. The impression was gained that repeated inoculation with S. cruzi may influence the myocardial changes differently according to the period between the reinoculations. A short period after the first inoculation is followed by more marked changes, while long periods are accompanied by slight changes, which suggests an active immunisation produced by the first inoculation. More data are required, however before a definite statement is made on this subject considering that individual variations, the natural capacity of reversion of the interstitial myocarditis and the employement of more than a species of Cebus monkeys probably exerts influence also in the results here reported.

Residual effect of lambdacyhalothrin on Triatoma infestans

Insecticidal residual effect and triatomine infestation rates in houses of a community fumigated with lambdcyhalothrin (Icon) are reported. No mortality was observed in 5th-instar Triatoma infestans nymphs in 72-hr exposure test on three different surfaces, one month after fumigation for a dose of 31.5 mg am/m2. However, during post-exposure observation a mortality of 60% was recorded for those insect exposed on sprayed woodboard. The results observed with mud-containing treated walls, were markedly poorer (0% of mortality). Twelve month after spraying 40% of mortality was observed on first-instar T. infestans nymphs in 72-hr exposure test on woodboard, but lower mortality rates were observed in mud-containing materials. When the effect of deltamethrin (109 mg ai/m2) and lambdcyhalothrin (94 mg ai/m2) was compared, the former did not appear to be superior at similar loads. Both have showed a mortality rate of 30% on 5th-instar T. infestans nymphs three months post-fumigation. The dose utilized in the field fumigation was enough to get a significant (p < 0.0001) control of triatomine domestic infestation, since it was sufficient to keep 95% of the houses uninfested throughout 21 months following treatment, when compared with baseline situation. A remarkable knock-down effect on adult and nymphs forms of the insect and a high in situ mortality were observed as a result of its application, even at very low doses.

Evaluation of the Molluscicidal Properties of Euphorbia splendens var. hislopii (N.E.B.) Latex: Experimental Test in an Endemic Area in the State of Minas Gerais, Brazil

Following the positive results obtained regarding the molluscicidal properties of the latex of Euphorbia splendens that were corroborated in laboratory and field tests under restricted conditions, a field study was conducted in experimental streams located in an endemic area. After recording the average annual fluctuations of vectors in three streams, a solution of E. splendens latex at 12 ppm was applied in stream A, a solution of niclosamide at 3 ppm that was applied in stream B and a third stream (C) remained untreated for negative control. Applications of E. splendens and niclosamide resulted in a mortality of 100% among the snails collected in the streams A and B. No dead snails were found in the negative control stream. A monthly follow-up survey conducted during three consecutive months confirmed the return of vectors to both experimental streams treated with latex and niclosamide. This fact has called for a need to repeat application in order to reach the snails that remained buried in the mud substrate or escaped to the water edge, as well as, newly hatched snails that did not respond to the concentration of these molluscicides. Adults snails collected a month following treatment led us to believe that they had migrate from untreated areas of the streams to those previously treated

Stratigraphy and palaeoenvironment of Early Jurassic dinosaur-bearing volcaniclastic deposits from Toundoute (Province of Ouarzazate, Haut-Atlas, Morocco)

The Early Jurassic dinosaur site of Toundoute which yielded the basal sauropod Tazoudasaurus naimi is examined in the light of its stratigraphic, sedimentological and palaeoenvironmental context. A thin succession of Early Liassic marine carbonates (probably Hettangian-Sinemurian in age) is continuously overlain by continental beds with dinosaurs. These latter are assumed to be of Middle to Late Liassic age. The continental deposits include a large part of volcanoclastics, different from the Triassic basalts. The Jurassic volcanoclastics originated from an unknown but obviously close eruption centre. The continental sediments (channels and flood plain) were deposited under tropical climate conditions with alternating humid and dry episodes. The bones occur as isolated or partly articulated elements (parts of carcasses). The two bone-beds are related to typical mud-flows. This type of transport protected the bones from erosion, and favoured their burying and fossilization.

Fipronil Insecticide: Novel Application against Triatomine Insect Vectors of Chagas Disease

We investigated the efficacy and the residual effect of fipronil® against two species of triatomine bugs, Triatoma infestans and Rhodnius neglectus, in laboratory conditions measuring concentration-response and residual activity on different surfaces (dried mud and lime coated mud). Lethal concentrations (LC50,90) were determined on filter paper. The higher insecticide efficacy against R. neglectus when compared to T. infestans may be partially attributed to the differences in their biological cycles and genetic structures. Comparison with lambdacyhalothrin wettable powder showed that fipronil mortality rates (above 50%) were observed on mud blocks and lime-coated mud blocks up to 3 months when fipronil was sprayed at 100 and 200 mg a.i./m². Residual effect deeply decayed after 3 months; and at 6 months post treatment mortality was not observed. In contrast, lambdacyhalothrin showed a long lasting residual effect on both surfaces up to 6 months. Also, it should be mentioned that fipronil had a slow, but lethal activity on the triatomine bugs when wettable formulations were used on porous surfaces.

Comparative evaluation of pyrethroid insecticide formulations against Triatoma infestans (Klug): residual efficacy on four substrates

We investigated the residual efficacy of four insecticide formulations used in Chagas disease vector control campaigns: cyfluthrin 12.5% suspension concentrace (SC), lambda-cyhalothrin 10% wettable powder (WP), deltamethrin 2.5% SC, and 2.5% WP on four types of circular blocks of wood, straw with mud, straw with mud painted with lime, and mud containing 5% of cement. Three concentrations of these insecticides were tested: the LC90 (previously determined on filter paper), the double of the LC90, and the recommended operational dose. For each bioassay test, 15 third-stage nymphs of Triatoma infestans (Klug) (Hemiptera: Reduviidae) were exposed for 120 h to each treatment at 24 h, 30, 60, 90, and 180 days post-spraying. Mortality rates, moulting history and behaviour were recorded at 24, 48, 72, and 120 h of exposure. Mortality rates were highest during the first 30 days post-spraying. Highest mortality rates (above 50%) were observed for deltamethrin 2.5% SC and lambda-cyhalothrin 10% WP on wood blocks up to three months post-spraying. Mud was the substrate on which treatments showed lowest persistence, with the other two substrates showing intermediate residual efficacy of all treatments. During the first 30 days WP formulations were not as effective as SC flowable formulations but, overall in the longer term, WP gave grater mortality rates of T. infestans nymphs exposed at up to six months post-spraying. Porous surfaces, especially mud, showed most variability presumably due to absorption of the insecticide. In contrast the less porous surfaces (i.e. wood and lime-coated mud) kept mortality rates high for longer post-treatment, irrespective of the insecticide concentration used.