Exigências térmicas de Aedes (Stegomyia) albopictus Skuse, 1894 (Diptera, Culicidae) em condições de laboratório

Thermal requirements of Aedes (Stegomyia) albopictus Skuse, 1894 (Diptera, Culicidae) under laboratory conditions. Allochtonous species of Ae. albopictus in the American continent can be found in fourteen Brazilian states - about fifteen years had been elapsed since the first report of the presence of this species in Brazilian territory. Considering its potential epidemiological importance and its adaptation to several habitats, it was determined, for this species, the threshold temperature and the thermal constant for egg, larval and pupal stages under laboratory conditions under four constant temperatures and 12:12 hours light-dark photoperiod. The threshold temperature for the egg phase and for the first instar were quite similar: 9.07 ºC (K=214.46 degree days) and 9.23 ºC (K= 36.64 degree days), respectively. For 2nd, 3rd and 4th instar, the basal-temperature was higher, oscilating between 12.26 ºC and 13.95 ºC. The threshold temperature for the complete larval stage and for the pupal stage were 12.03 ºC (K= 99.48 degree days) and 11.87 ºC (K=32.40 degree days) for males and 11.95 ºC (K=110.11 degree days) and 11.60 ºC (K=35.30 degree days) for females, respectively.

Dynamics of the control of Aedes (Stegomyia) aegypti Linnaeus (Diptera, Culicidae) by Bacillus thuringiensis var israelensis, related with temperature, density and concentration of insecticide

The dynamics of the control of Aedes (Stegomyia) aegypti Linnaeus, (Diptera, Culicidae) by Bacillus thuringiensis var israelensis has been related with the temperature, density and concentration of the insecticide. A mathematical model for biological control of Aedes aegypti with Bacillus thuringiensis var israelensis (Bti) was constructed by using data from the literature regarding the biology of the vector. The life cycle was described by differential equations. Lethal concentrations (LC50 and LC95) of Bti were determined in the laboratory under different experimental conditions. Temperature, colony, larvae density and bioinsecticide concentration presented marked differences in the analysis of the whole set of variables; although when analyzed individually, only the temperature and concentration showed changes. The simulations indicated an inverse relationship between temperature and mosquito population, nonetheless, faster growth of populations is reached at higher temperatures. As conclusion, the model suggests the use of integrated control strategies for immature and adult mosquitoes in order to achieve a reduction of Aedes aegypti.

Improvement of a test-chamber for behavioral studies on adult females of Aedes aegypti (Linnaeus) (Diptera, Culicidae)

A test-chamber (K&L-Chamber) made of cardboard and acrylic plastic, and consisting in four sections (A, B, C and D) was developed by Klowden & Lea (1978) for Aedes aegypti host-seeking behavior studies. Later, Foster & Lutes (1985) also used an identical chamber to successfully evaluate the efficacy of electronic repellers. It was described here a modified K&L-Chamber for behavioral studies of Ae. aegypti adults. The chamber was made in polystyrene, consisting of three sections (A, B and C) and using a human hand and a fluorescent lamp as stimulus to attract the mosquitoes. The suitability of the present test-chamber was validated assaying 80 replicates and releasing 10 Ae. aegypti females in each replicate. The females were released in the section A and allowed to fly to the section C. A mean of 96.0% (s.e. 0.213) Ae. aegypti females successfully reached section C. The present test-chamber is cheaper and easier to handle and as efficient as K&L-Chamber, when compared to Foster & Lutes (1978) that noticed 93.8% of Ae. aegypti reaching the trap section.

Adultrap: descrição de armadilha para adulto de Aedes aegypti (Diptera, Culicidae)

A Adultrap é uma nova armadilha para capturar Aedes aegypti. Esta tem forma cilíndrica, cor escura, formando três compartimentos, sendo um para isca, um para entrada do adulto e outro para retê-lo dentro da armadilha. Tanto no laboratório quanto no campo, os ensaios mostraram que a armadilha apresentou positividade na captura de adulto de Ae. aegypti. Esses ensaios sugerem mais estudos para avaliar a especificidade da Adultrap para capturar esta espécie.

Perfil de Suscetibilidade da População de Aedes aegypti (Diptera: Culicidae) da ilha de Santiago, Cabo Verde, a inseticidas

Em Cabo Verde, arquipélago situado na Costa Ocidental Africana, os primeiros casos de dengue ocorreram em 2009, com a notificação de mais de 21.000 casos, a maioria desses registrados na Ilha de Santiago. O mosquito Aedes aegypti foi identificado como vetor, e ações para seu controle, usando os inseticidas temephos (larvicida) e a deltametrina (adulticida), têm sido implementadas. Objetiva-se com esse trabalho avaliar o atual status de suscetibilidade a inseticidas e caracterizar os mecanismos de resistência nessa população. Amostras de A. aegypti da ilha de Santiago foram coletadas através de armadilhas de oviposição, para o estabelecimento de uma população a ser analisada. Foram realizados bioensaios do tipo dose diagnóstica, usando garrafas impregnadas com doses únicas dos adulticidas malathion (organofosforado), deltametrina (piretróide) e cipermetrina (piretróide), e bioensaios do tipo dose resposta, usando múltiplas concentrações dos inseticidas temephos (organofosforado), Bacillus thuringiensis sorovariedade israelensis (bactéria entomopatogênica) e diflubenzuron (inibidor de síntese de quitina). Para a investigação dos mecanismos de resistências, foram realizados testes bioquímicos com substratos específicos para quantificar a atividade das enzimas glutationa S-transferases, esterases (α, β e PNPA) e oxidases de função mista, ligadas a detoxificação de xenobióticos, e a taxa de inibição da acetilcolinesterase ligada a insensibilidade do sítio alvo. Pesquisou-se também a presença de mutaçõeso do tipo kdr (knock-down resistance) associadas à resistência a piretróides, pela análise da sequência dos exons 20 e 21 no gene do canal de sódio. Nos resultados dos bioensaios constatou-se que a população de A. aegypti investigada apresenta resistência aos piretróides deltametrina e cipermetrina (mortalidade <80%) e ao organofosforado temephos (RR90=4), mas é suscetível ao malathion (mortalidade ≥98%), Bacillus thuringiensis sorovariedade israelensis (RR90=0.8) e ao diflubenzuron (RR90=2,2). Em relação a atividade das enzimas ligadas ao processo de detoxificação, foram detectadas alterações nas glutationa S-transferases (25%), oxidases de função mista (18%), esterase-α (19%) e esterase- β (17%). A taxa de inibição da acetilcolinesterase (6%) e a atividade da esterase-PNPA (7%) mostraram que estas estão inalteradas. Nenhuma das mutações do tipo kdr pesquisadas foi detectada. Estes resultados permitem concluir que a população de A. aegypti da ilha de Santiago, Cabo Verde, é suscetível aos inseticidas, excetuando os piretróides testados e o temephos, usados no seu controle; e que ela apresenta alterações em enzimas detoxificadoras que poderão estar implicadas na resistência a esses compostos.

Evaluation of oviposition traps as an entomological surveillance method for Aedes aegypti (Diptera, Culicidae)

This study aimed to describe the behavior of oviposition traps for Aedes aegypti over time, to compare it with the larval survey and to investigate the association with climatic variables. It was conducted in São José do Rio Preto city, São Paulo. Daily climatic data and fortnightly measurements for oviposition traps and larval infestation were collected from October 2003 to September 2004. Three different periods were identified in the behavior of oviposition traps' positivity and mean number of eggs: increase, plateau and decrease in values. These measurements followed the variation of climatic data from the first and third periods. High correlation was obtained between the positivity and the mean number of eggs. The oviposition traps showed higher capacity to detect the vector than did larval survey. It was observed that the first (October to December) and third (May to September) periods were considered to be the most suitable to use oviposition traps than larval surveys.

Impact of small variations in temperature and humidity on the reproductive activity and survival of Aedes aegypti (Diptera, Culicidae)

In short space of time increase in temperature and rainfall can affect vector populations and, consequently, the diseases for them transmitted. The present study analyzed the effect of small temperature and humidity variations on the fecundity, fertility and survival of Aedes aegypti. These parameters were analyzed using individual females at temperatures ranging from 23 to 27 °C (mean 25 °C); 28 to 32 °C (mean 30 °C) and 33 to 37 °C (mean 35 ºC) associated to 60±8% and 80±6% relative humidity. Females responded to an increase in temperature by reducing egg production, oviposition time and changing oviposition patterns. At 25 ºC and 80% relative humidity, females survived two-fold more and produced 40% more eggs when compared to those kept at 35 ºC and 80% relative humidity. However, in 45% of females kept at 35 ºC and 60% relative humidity oviposition was inhibited and only 15% females laid more than 100 eggs, suggesting that the intensity of the temperature effect was influenced by humidity. Gradual reductions in egg fertility at 60% relative humidity were observed with the increase in temperature, although such effect was not found in the 80% relative humidity at 25 º C and 30 º C. These results suggest that the reduction in population densities recorded in tropical areas during seasons when temperatures reach over 35 ºC is likely to be strongly influenced by temperature and humidity, with a negative effect on several aspects of mosquito biology.

Temporal distribution of Aedes aegypti Linnaeus (Diptera, Culicidae), in a Hospital in Cuiabá, State of Mato Grosso, Brazil

This study aimed at registering and monitoring the presence of Aedes aegypti in the University Hospital Júlio Muller, Cuiabá-MT, as well as investigating the influence of temperature and rainfall on its temporal distribution and egg densities in ovitraps. The study was performed from April/2007 to March/2008, utilizing ovitraps with 10% of hay infusion and a wood paddle as an oviposition substrate. For surveillance, one ovitrap was placed in each of the 12 points distributed throughout the hospital. Ovitraps were collected monthly at the end of a 5-day installation period. After egg counting, wood paddles were immersed in water to allow larval eclosion for species identification through optical microscopy. Egg Density Index (EDI), Positive Ovitraps Index (POI), and Mean Number of Eggs (MNE) were used for data analysis. The presence of A. aegypti in the hospital was registered throughout the study period, except in July. The MNE was proportionally higher in the internal area (n= 8.47 eggs/paddle) when compared to the external area (n= 5.46 eggs/paddle), and was higher in September/October 2007 and January/February 2008. A significant increase in EDI, POI and MNE was registered in periods where the average temperature was higher, and the increase in POI was also concomitant with an increase in rainfall. The continuous presence of A. aegypti in the hospital throughout the study period, points out the need of including this mosquito in the arthropod control list in this environment. This is particularly important, considering that A. aegypti is an important vector of several arboviroses.

Genetic variability of a population of Aedes aegypti from Paraná, Brazil, using the mitochondrial ND4 gene

Genetic variability of a population of Aedes aegypti from Paraná, Brazil, using the mitochondrial ND4 gene. To analyze the genetic variability of populations of Aedes aegypti, 156 samples were collected from 10 municipalities in the state of Paraná, Brazil. A 311 base pairs (bp) region of the NADH dehydrogenase subunit 4 (ND4) mitochondrial gene was examined. An analysis of this fragment identified eight distinct haplotypes. The mean genetic diversity was high (h = 0.702; p = 0.01556). AMOVA analysis indicated that most of the variation (67%) occurred within populations and the F ST value (0.32996) was highly significant. F ST values were significant in most comparisons among cities. The isolation by distance was not significant (r = -0.1216 and p = 0, 7550), indicating that genetic distance is not related to geographic distance. Neighbor-joining analysis showed two genetically distinct groups within Paraná. The DNA polymorphism and AMOVA data indicate a decreased gene flow in populations from Paraná, which can result in increased vectorial competence.

Isolation of Bacillus thuringiensis from the state of Amazonas, in Brazil, and screening against Aedes aegypti (Diptera, Culicidae)

We investigated the use of Bacillus thuringiensis isolated in the state of Amazonas, in Brazil, for the biological control of the dengue vector Aedes aegypti. From 25 soil samples collected in nine municipalities, 484 bacterial colonies were obtained, 57 (11.78%) of which were identified as B. thuringiensis. Six isolates, IBt-03, IBt-06, IBt-07, IBt-28, IBt-30, and BtAM-27 showed insecticidal activity, and only BtAM-27 presents the five genes investigated cry4Aa, cry4Ba, cry10Aa, cry11Aa, and cry11Ba. The IBt-07 and IBt- 28, with lower LC50 values, showed equal toxicity compared to the standards. The isolates of B. thuringiensisfrom Amazonas constitute potential new means of biological control for A. aegypti, because of their larvicidal activity and the possibility that they may also contain new combinations of toxins.

Contrasting patterns of insecticide resistance and knockdown resistance (kdr) in Aedes aegypti populations from Jacarezinho (Brazil) after a Dengue Outbreak

ABSTRACT After a dengue outbreak, the knowledge on the extent, distribution and mechanisms of insecticide resistance is essential for successful insecticide-based dengue control interventions. Therefore, we evaluated the potential changes to insecticide resistance in natural Aedes aegypti populations to Organophosphates (OP) and Pyrethroids (PY) after chemical vector control interventions. After a Dengue outbreak in 2010, A. aegypti mosquitoes from the urban area of Jacarezinho (Paraná, Brazil) were collected in 2011 and 2012. Insecticide resistance to OP Temephos was assessed in 2011 and 2012 by dose–response bioassays adopting WHO-based protocols. Additionally, in both sampling, PY resistance was also investigated by the Val1016Ile mutation genotyping. In 2011, a random collection of mosquitoes was carried out; while in 2012, the urban area was divided into four regions where mosquitoes were sampled randomly. Bioassays conducted with larvae in 2011 (82 ± 10%; RR95 = 3.6) and 2012 (95 ± 3%; RR95 = 2.5) indicated an incipient altered susceptibility to Temephos. On the other hand, the Val1016IIe mutation analysis in 2011, presented frequencies of the 1016Ilekdr allele equal to 80%. Nevertheless, in 2012, when the urban area of Jacarezinho was analyzed as a single unit, the frequency of the mutant allele was 70%. Additionally, the distribution analysis of the Val1016Ile mutation in 2012 showed the mutant allele frequencies ≥60% in all regions. These outcomes indicated the necessity of developing alternative strategies such as insecticide rotations for delaying the evolution of resistance.

[Magnificentiores selectioresque Urbis Venetiarum prospectus quos olim Michael Marieschi, Venetus pictor et architectus in plerisque tabulis depinxit, nunc vero ab ipsomet acurate delineante, incidente, tyspisque mandante, iterum in sexdecim aereis tabulis in lucem aeduntur]. [4], Pisaurum Familiae AEdes ad Canalis magni marginem, una cum D: Eustachii templo dextrorsum, et sinistrorsum cum parte Corneliorum aedis : [estampe] / Mich.l Marieschi del.t et inci.t

Référence bibliographique : Toledano, Marieschi, 31b

[Magnificentiores selectioresque Urbis Venetiarum prospectus quos olim Michael Marieschi, Venetus pictor et architectus in plerisque tabulis depinxit, nunc vero ab ipsomet acurate delineante, incidente, tyspisque mandante, iterum in sexdecim aereis tabulis in lucem aeduntur]. [11], Forum olitorium e regione prospectum, cum proximis publicis Magistratibus, et ponte Rivoalti : citra pontem aedes mercatoria gentis Germanicae ad laevam. : [estampe] / Mich.l Marieschi del.t et inci.t

Référence bibliographique : Toledano, Marieschi, 10e

[Magnificentiores selectioresque Urbis Venetiarum prospectus quos olim Michael Marieschi, Venetus pictor et architectus in plerisque tabulis depinxit, nunc vero ab ipsomet acurate delineante, incidente, tyspisque mandante, iterum in sexdecim aereis tabulis in lucem aeduntur]. [13], Forum maius, et Basilica D: Marci, cum insula procul S. Georgii maioris et aedes D: Marci Procuratorum, vulgo novae ad dexteram : omnia ab horologia prospecta. : [estampe] / Mich.l Marieschi del.t et inci.t

Référence bibliographique : Toledano, Marieschi, 2f

[Magnificentiores selectioresque Urbis Venetiarum prospectus quos olim Michael Marieschi, Venetus pictor et architectus in plerisque tabulis depinxit, nunc vero ab ipsomet acurate delineante, incidente, tyspisque mandante, iterum in sexdecim aereis tabulis in lucem aeduntur]. [3], Foscarorum ades ad levam, et e conspectu altera Balborum ambo praeter canalem magnum ; ubi etiam solemne nauticum certamen, et maxima prequentia cymbarum vel auro vel argento vel alio ornatu obductarum, fictasque formas exhibentium cernuntur, nec non lintres naviculariorum pro brabrio certantium. Inter easdem aedes exornata ad maiorem spectaculi dignitatm meta super acquas erigitur. : [estampe] / Mich.l Marieschi del.t et inci.t

Référence bibliographique : Toledano, Marieschi, 35d