Relative growth and sexual maturity of the freshwater shrimp Palaemon pandaliformis (Crustacea, Palaemonidae) in northeastern of Brazil (Canavieiras, Bahia)

This study comprises the description of relative growth and sexual maturity of a population of Palaemon pandaliformis Stimpson, 1871 in Salsa River (Northeastern Brazil). Samples were collected monthly between September 2009 and August 2010. Females were larger, heavier, and showed a greater allometric coefficient (b) than male specimens. Only carapace length vs. pleura length in females presented a significant difference in the relative growth pattern, indicating a puberty moult. This relationship is strictly correlated to reproduction and its success rate in female shrimps. Estimated carapace length in 50% of mature females (CL50) was 4.53 mm. It was not possible to compare obtained CL50 results due to a lack of studies on this species. Comparison was based on the size of the smallest captured ovigerous female (3.81 CL mm), which is within the scope of recorded size for estuaries located in higher latitudes. This study reveals the lack of research on this genre in freshwater environments on a national and global scale.

Reproductive aspects of Dendropsophus sanborni (Anura, Hylidae) in northeastern Argentina

Reproductive aspects of Dendropsophus sanborni (Anura, Hylidae) in northeastern Argentina. The aim of this investigation was to characterize reproductive aspects of Dendropsophus sanborni (Schmidt, 1944) (Anura, Hylidae) in the northwest of Corrientes province, in northeastern Argentina. The reproductive cycles of males and females, the existence of sexual dimorphism and the male’s vocalization period were analyzed. Samplings were made from September 2011 to August 2012. Dendropsophus sanborni showed a prolonged reproductive pattern because reproductive activity was observed during most part of the year. Calling males were recorded all months except in July. The spermatogenic cycle can be characterized as potentially continuous. In males, snout-vent length was significantly correlated with mean testicular volume. The species showed sexual dimorphism in body mass, with females larger than males. Post-ovulatory females were found from March to June and most females had oocytes at different stages of maturity, with abundant post-vitellogenic oocytes from August to December.

New field observations on the competitive displacement between two species of planorbid snails inhabiting Northeastern Brasil

Observations reported in the present paper have shown that Biomphalaria glabrata is being gradually displaced by B. straminea in coastal areas of two counties on the state of Pernambuco, Brazil, confirming former observations made in the same region.

Spatial and seasonal trends of a natural population of Biomphalaria occidentalis in northeastern Argentina

This study aims to analyze the age of a population of Biomphalaria occidentalis on a pound of Riachuelo river basin, wich is one of the three most important Middle Paraná river affluents in Corrientes province. Samples were drawn from three stations, were spatial and temporal numerical variations of the snail, as well as its relation with different environmental parameters, mainly temperature, rainfall, pH and conductivity, were analyzed. Snail abundance is given in number of individuals/hour. The differences between the three sampling stations, estimated by nonparametric tests, was nonsignificant. A relative scale to the greatest shell diameter was employed to build the age pyramids. Temporal fluctuations of snail abundance correlated negatively with the highest monthly accumulated temperatures (P < 0.05). Although different floristic compositions were observed at the three stations, no significant numerical variations were detected in B. occidentalis spatial distribution. Reproductive activity took place between March-April and November with overlapping cohort system. During summer (December-Febuary) mortality increased along with temperature and reproductive activity was not evident.

Ecology of phlebotomine sand flies (Diptera: Psychodidae)in a focus of Leishmania (Viannia) brasiliensis in northeastern Colombia

The phlebotomine sand fly fauna of two coffee plantations in a Leishmania-endemic area of Norte de Santander, Colombia was studied. Regular insect collections using a variety of methods were made for three and a half years. Information was obtained on diurnal resting sites, host range and seasonal abundance for 17 species, of wich five (Lutzomyia spinicrassa, Lu. serrana,Lu. shannoni, Lu. ovallesi and Lu. gomezi) were far more numerous than the others, anthropophilic and present throughout the year. The behaviour of these and the remaining 12 species is discussed in relation to their potential role in transmission of Leishmania (Viannia) brasiliensis in the area.

Climatic change in northeastern Brazil: paleoparasitological data

Trichuris eggs were observed in Kerodon rupestris coprolites dated 9,000 years before present, collected in archeological sites of São Raimundo Nonato, northeastern Brazil. However, present day local rodents seem not to be infected by the parasite, suggesting its disappearence due to climatic changes.

Epidemiological study of bancroftian filariasis in Recife, Northeastern Brazil

Wuchereria bancrofti in Pernambuco was first documented in 1952 (Azevedo & Dobbin 1952), and since then it has been reported in surveys carried out in selected areas of Recife. Several surveys were carried out from 1981 to 1991 by SUCAM. In the 1985 SUCAM's report the disease is considered under control. The CPqAM Filariasis Research Program was established in 1985 and a filarial survey was carried out in the town of Olinda, Greater Recife. In order to verify the real epidemiological situation, a study was conducted in the city of Recife. 21/36 of the Special Zones of Social Interest (ZEIS), were randomly selected for the present study. From 10,664 persons screened, 683 were positive and the prevalence rate for microfilaraemia (mf) varied from 0.6% to 14.9%. A mean mf prevalence of 6.5%, showed that the infection occurs in a wide geographic distribution in Greater Recife and that the intensity of transmission is a real and potential threat to public health in affected communities. Mf rate among males and females differed significantly. Due to the rapid increase in population, unplanned urban settlements, poor sanitary facilities and the favorable geographical conditions to the development of the vector, filariasis may actually be increasing in Recife.

Lutzomyia derelicta (Diptera: Psychodidae) a singular new phlebotomine sand fly from an inselberg in northeastern amazonia

Lutzomyia derelicta n. sp. is described from specimens collected in an isolated xeric habitat in the rainforest in the north of the State of Pará, Brazil. The new species lacks the posterior bulge in the dorsal wall of the cibarium characteristic of the New World genus Lutzomyia, and the armature of the male genitalia is of the pattern found elsewhere only in the Old World species of Sergentomyia. L. derelicta is phenetically intermediate between the known species of Lutzomyia and Sergentomyia, and cannot readily be placed in any existing subgenus or species group of either genus.

Population dynamics and feeding behavior of Triatoma brasiliensis and Triatoma pseudomaculata, main vectors of Chagas disease in Northeastern Brazil

Biological parameters of Triatoma brasiliensis and T. pseudomaculata that could influence the epidemiological importance of these insects as vectors of Trypanosoma cruzi were compared. The parameters studied were incubation period, interval between hatching or moulting and first feeding, number of blood meals, development time, mortality, net reproductive rate, instantaneous daily reproductive rate, time-lapse before starting feeding, duration of feeding, blood ingestion capacity, occurrence of defecation and blood ingestion velocity. Most aspects of feeding were similar for the two species, although T. pseudomaculata had a longer life cycle than T. brasiliensis producing one and two generations per year, respectively. The two species had similar instantaneous daily rates of population growth.

Triatoma sordida Stål 1859 (Hemiptera, Reduviidae: Triatominae) in palms of northeastern Argentina

Several palms species provide an important habitat for triatomines and associate vertebrates in tropical America. The objective of this work is to identify the triatomine species living in the palms of rural areas in the Province of Corrientes, and to estimate the potential epidemiological risk they represent for the residents of nearby houses. The survey was carried out in a palm community in Colonia Laurel, Department San Roque, Province of Corrientes, Argentina. Samplings were performed in October, November and December 1998; January, February and March 1999; May and June 1999. Thirty palms: 27 (90%) Butia yatay (Mart.) Becc. and 3 Acrocomia aculeata (Jacq.) Lodd ex Mart. were dissected. Triatoma sordida Stål 1859 was found in 96.2% of B. yatay and in all the A. aculeata palms. A total of 272 live T. sordida was collected; 36 of them (13.2%) were found in bird nests in the frond and the remainder in other locations of the tree. The mean number of triatomines per palm was 9.6 (range 1-60, mode 2). T. sordida was collected during all the sampling months and all stages were present at all seasons. The highest population density was reached in spring and the lowest in autumn. Trypanosoma cruzi was detected in 38.5% in feces of 174 examined insects and identified as such, both by microscopical examination and PCR. This is the first finding of T. sordida populations in B. yatay, an endemic palm of South America distributed in southern Brazil, Uruguay and northeastern Argentina. The high infection prevalence found in this work suggests that T. sordida plays an essential role in the maintenance of the wild T. cruzi transmission cycle in northeastern Argentina.

Ecological Aspects of Phebotomine (Diptera, Psychodidae) in an Endemic Area of Tegumentary Leishmaniasis in the Northeastern Argentina, 1993-1998

The first epidemic tegumentary leishmaniasis´ outbreak in the province of Misiones was recorded in 1998, in the locality of Puerto Esperanza. Phlebotominae collected in the region, previously or simultaneously to the outbreak (September 1993-December 1998) showed that the species Lutzomyia intermedia s. l. was prevalent (94%, n 6,150) at all the sites sampled with miniature light trap (10) and Shannon trap (3). L. pessoai, L. whitmani, L. migonei, L. shannoni, L. fischeri, L. misionensis, Brumptomyia avellari and B. guimaraesi were also captured. Sand fly distribution in time and space suggests that in the province of Misiones (1) the species already present before 1990 could give rise to the epidemic by the density/dispersion fluctuation of their local populations; (2) the abundance of L. intermedia s. l. was associated with environments with ecotones of primary-secondary vegetation, close to water bodies and with moderate human disturbance; (3) this species showed, towards the end of 1997, peaks of exceptional abundance, subsequent to rainfall peaks in 1996. This increase in abundance of potential vector sand fly populations close to houses with colonizable surroundings could have generated the 1998 epidemic outbreak.

Interrelationship between ectoparasites and wild rodents from northeastern Buenos Aires province, Argentina

Infestation parameters and indices of mites, ticks and fleas associated with wild rodents from northeastern Buenos Aires Province, Argentina, were studied. Host species similarity was also analyzed in relation to their ectoparasites. Fifty-five rodents were captured from January 2000 to March 2001. In total, 1,022 ectoparasites were collected and three ectoparasite-host associations were new records. However, this is the first study on Craneopsylla minerva wolffhuegeli infesting parameters. Ectoparasite total mean abundance and total prevalence were higher in Holochilus brasiliensis (MA = 47.7; P = 100%) and Scapteromys aquaticus (MA = 25.4; P = 95.4%), meanwhile specific richness and diversity were higher in Oligoryzomys flavescens (S = 6; H = 1.3) and Akodon azarae (S = 4; H = 1.0). On the other hand, the only individual of Calomys laucha was not parasited. S. aquaticus-H. brasiliensis, which preferred similar microhabitats, shared the same ectoparasite species (Css = 100). Whereas, A. azarae, which was mostly associated with grassland, showed the highest difference with the other hosts (Css < 0.4). Considering every ectoparasite species, H. brasiliensis showed the highest mean abundance, prevalence and preference. The results suggest that the particular characteristics of this rodent would give it better possibilities not only of being infested by ectoparasites, but also of transmitting them to its progeny.

Random amplified polymorphic DNA analysis of Anopheles nuneztovari (Diptera: Culicidae) from Western and Northeastern Colombia

Random amplified polymorphic DNA (RAPD) markers were used to analyze 119 DNA samples of three Colombian Anopheles nuneztovari populations to study genetic variation and structure. Genetic diversity, estimated from heterozygosity, averaged 0.34. Genetic flow was greater between the two populations located in Western Colombia (F ST: 0.035; Nm: 6.8) but lower between these two and the northeastern population (F ST: 0.08; Nm: 2.8). According to molecular variance analysis, the genetic distance between populations was significant (phiST 0.1131, P < 0.001). The variation among individuals within populations (phiST 0.8869, P < 0.001)was also significant, suggesting a greater degree of population subdivision, not considered in this study. Both the parameters evaluated and the genetic flow suggest that Colombian An. nuneztovari populations are co-specific.

Aspects of peridomiciliary ecotopes in rural areas of Northeastern Brazil associated to triatomine (Hemiptera, Reduviidae) infestation, vectors of Chagas disease

Artificial ecotopes of 121 peridomiciliary environments in four rural localities in the state of Ceará, Brazil, were studied and the type of material of the ecotopes was identified as triatomine infestation. Two thousand two hundred and four Triatoma brasiliensis Neiva, 340 Triatoma pseudomaculata Corrêa and Espínola, 121 Rhodnius nasutus Stall, and 5 Panstrongylus lutzi (Neiva and Pinto) were captured. Out of the 323 ecotopes found (X =2.0 ± 1.8 per dwelling) such as pigpens, henhouses, corrals, perches, dovecotes, piles of roofing tiles, bricks, wood, and straw 30.3% were infested by triatomines in all different developmental stages, including eggs. A substantial number of triatomines were found in perches, however the largest infestation took place in roofing materials used in the construction of goat/sheep corrals, henhouses, and pigpens, where 98% of them were captured: 1372 triatomines were located in the roofing tile covers, 285 in the straw, 187 in the perches, 77 in the coverings of roofing tiles and straw, and 13 in the straw and wood. Among all the different pile of materials, roofing tiles were the most infested (50%) followed by bricks (38.9%) and woods (36.1%). T. brasiliensis colonized mainly brick piles (chi2=16.539; p < 0.05) and roofing tiles (chi2=5,090.58; p < 0.05); T. pseudomaculata preferred wood perches (chi2= 472.39; p < 0.05) and woodpiles (chi2=126.0 p < 0.05), and R. nasutus was principally found in roofing straw (chi2=384.43; p < 0.05). These findings suggest that triatomines tend to colonize peridomiciliary ecotopes similar to their original habitats.