ABSTRACT Changes in physiology of the nervous system and metabolism can be detected through the activity of acetylcholinesterase (AChE), alpha esterase (EST-a) and beta esterase (EST-ß) in chironomids exposed to pollutants. However, to understand the real effect of xenobiotics on organisms, it is important to investigate how certain factors can interfere with enzyme activity. We investigated the effects of different temperatures, food stress and two steps of the enzymatic protocol on the activity of AChE, EST-a and EST-ß in Chironomus sancticaroli. In experiment of thermal stress individuals from the egg stage to the fourth larval instar were exposed to different temperatures (20, 25 and 30 °C). In food stress experiment, larvae were reared until IV instar in a standard setting (25 °C and 0.9 g weekly ration), but from fourth instar on they were divided into groups and offered different feeding regimes (24, 48 and 72 h with/without food). In sample freezing experiment, a group of samples was processed immediately after homogenization and another after freezing for 30 days. To test the effect of centrifugation on samples, enzyme activity was quantified from centrifuged and non-centrifuged samples. The activity of each enzyme reached an optimum at a different temperature. The absence of food triggered different changes in enzyme activity depending on the period of starvation. Freezing and centrifugation of the samples significantly reduced the activity of three enzymes. Based on these results we conclude that the four factors studied had an influence on AChE, EST-a and EST-ß and this influence should be considered in ecotoxicological approaches.

Mosquito control prevails as the most efficient method to protect humans from the dengue virus, despite recent efforts to find a vaccine for this disease. We evaluated insecticide resistance and genetic variability in natural populations of Aedes aegypti (Linnaeus, 1762) from Colombia. This is the first Colombian study examining kdr mutations and population structure. Bioassays with larvae of three mosquito populations (Armenia, Calarcá and Montenegro) were performed according to the World Health Organization (WHO) guidelines, using Temephos. For the analysis of the Val1016Ile mutation and genetic diversity, we sampled recently-emerged adults from four mosquito populations (Armenia, Calarcá, Montenegro and Barcelona). Following the WHO protocol, bioassays implemented with larvae showed resistance to Temephos in mosquito populations from Armenia (77% ± 2) and Calarcá (62% ± 14), and an incipient altered susceptibility at Montenegro (88% ± 8). The RR95 of mosquito populations ranged from 3.7 (Montenegro) to 6.0 (Calarca). The Val1016Ile mutation analysis of 107 genotyped samples indicates that 94% of the specimens were homozygous for the wild allele (1016Val) and 6% were heterozygous (Val1016Ile). The 1016Ile allele was not found in Barcelona. Genetic variability analysis found three mitochondrial lineages with low genetic diversity and gene flow. In comparison with haplotypes from the American continent, those from this study suggest connections with Mexican and North American populations. These results confirm that a continuous monitoring and managing program of A. aegypti resistance in the state of Quindío is required.

Low malathion concentrations influence metabolism in Chironomus sancticaroli (Diptera, Chironomidae) in acute and chronic toxicity tests. Organophosphate compounds are used in agro-systems, and in programs to control pathogen vectors. Because they are continuously applied, organophosphates often reach water sources and may have an impact on aquatic life. The effects of acute and chronic exposure to the organophosphate insecticide malathion on the midge Chironomus sancticaroli are evaluated. To that end, three biochemical biomarkers, acetylcholinesterase (AChE), alpha (EST-α) and beta (EST-β) esterase were used. Acute bioassays with five concentrations of malathion, and chronic bioassays with two concentrations of malathion were carried out. In the acute exposure test, AChE, EST-α and EST-β activities declined by 66, 40 and 37%, respectively, at 0.251 µg L-1 and more than 80% at 1.37, 1.96 and 2.51 µg L-1. In chronic exposure tests, AChE and EST-α activities declined by 28 and 15% at 0.251 µg L-1. Results of the present study show that low concentrations of malathion can influence larval metabolism, indicating high toxicity for Chironomus sancticaroli and environmental risk associated with the use of organophosphates.

We introduce a new, high quality, low cost and versatile LEDs-based handset device that emits high power UV and white light, which can be used interchangeably. It offers power control and has long battery life. Even though it is optimized to detect and collect scorpions under low light conditions, it can also be used with other groups of fluorescent organisms. The device achieved superior performance in field and laboratory trials when compared with a 12 LEDs low power UV flashlight, and a 46 W black fluorescent light lamp, to locate Tityus serrulatus Lutz & Mello, 1922.

Determining the age composition of a population is important when conducting ecological, taxonomic and environmental assessments. Morphometric measurements of the head capsule, especially the length and width, are widely used in the identification of insect instars, but alternative ways for determining the age of insects can expand the options for the analysis of field and laboratory populations. This study evaluated the morphometry of the antennae, mandibles, mentum and ventromental plates to discriminate among the four larval instars of Chironomus sancticaroli Strixino & Strixino, 1981. The larvae were reared in the laboratory under constant temperature (25°C) and photoperiod of 12/12 hours for 19 days, with a supply of food. Fifteen larvae were removed randomly every day, cleared in KOH, and slide-mounted, and had the antennae, mandibles, mentum and ventromental plates measured. The dimensions of the four structures studied allowed us to statistically distinguish each of the four larval instars. The data fit an exponential equation according to the Brooks-Dyar rule, which allows an estimate of the larval instar of specimens collected in the field, even when development takes place under different conditions. The duration of each instar was also obtained from our data, and showed an overlap of instars during development.

The genetic variability of populations of Aedes (Stegomyia) aegypti (Linnaeus, 1762) is often low due to the intense selection pressure caused by chemical control measures. In this study, we evaluated the susceptibility of larvae and adults of this mosquito to chemical insecticides, the frequency of the Val1016IIe mutation, and the genetic variability of the mitochondrial ND4 gene fragment in the urban area of Foz do Iguaçu, Paraná. The populations of A. aegypti in the southern and central regions of the city were resistant to the diagnostic dose of temephos 0.0162 ppm. Additionally, we detected difference in susceptibility in the northern population. The resistance ratios (RR95) were 3.8, 4.1, and 4.6 for the populations in the north, central, and south of the city, respectively. The entire population of A. aegypti in Foz do Iguaçu is resistant to pyrethroids. The mortality rates are as follows: 72.2% for cypermethrin (CD: 146 mg i.a./m²) and 57% for deltamethrin (CD: 18 mg i.a./m²). These results corroborate the hypothesis that the mutated 1016Ile allele is present in all analyzed strata. Out of the 234 samples genotyped for the Val1016Ile mutation, 15% were homozygous dominant for the wild allele (Val/Val), 62% were heterozygous (Va/Ile) and 23% were homozygous for the recessive mutation (Ile/Ile). With respect to the genetic variability of the mitochondrial ND4 gene fragment, 93% of the sequences analyzed belonged to haplotype 1, and 7% belonged to haplotype 2. The genetic diversity was low, the fixation index was not significant, and gene flow was high. The control of A. aegypti in Foz do Iguaçu using temephos and pyrethroids may be compromised because of the reduced vector susceptibility. Populations of A. aegypti, that undergoes a sudden reduction in effective population size and become resistant to pyrethroids may differ from the original population in vector capacity.

Atividade crepuscular de culicídeos (Diptera, Culicidae) no peridomicílio e remanescentes de matas ciliares do Rio Tibagi. Estado do Paraná, Brasil. Mosquitos atraídos por humanos foram coletados por uma hora em torno do crepúsculo vespertino (meia hora antes e meia hora depois), de abril a dezembro de 2006, em dois locais (mata ciliar e peridomicílio) na bacia do Rio Tibagi, município de Palmeira, Estado do Paraná. Foram capturados 749 mosquitos distribuídos em 13 espécies. Psorophora champerico Dyar & Knab, 1906 (42,86%) e Ps. discrucians (Walker, 1856) (40,59%) foram as espécies mais freqüentes. Não foram registradas diferenças significativas entre as médias de indivíduos capturados entre os pontos de mata ciliar e peridomicílio para Ps. champerico (t = -0,792; g.l. = 16; p = 0,43) e para Ps. discrucians (t = 0,689; g.l. = 16; p = 0,49). Isto demonstra que os dois ambientes estudados fornecem condições semelhantes para a atividade crepuscular destas espécies. Psorophora champerico e Ps. discrucians responderam (atividade hematofágica) aos estímulos ambientais associados ao horário crepuscular de forma distinta nos diferentes habitats analisados. Foi registrada pela primeira vez a presença de Psorophora champerico no bioma Mata Atlântica.

Crepuscular activity of culicids (Diptera, Culicidae) in the peridomicile and in the remaining riparian forest in Tibagi river, State of Paraná, Brazil. Human-attracted mosquitoes were collected for one hour, around sunset time (half hour before and half after), from April to December 2006, in two environments (riparian forest and near houses), in Tibagi river basin, Palmeira municipality, State of Paraná. Seven-hundred forty-nine mosquitoes, belonging to 13 species, were collected. Psorophora champerico Dyar & Knab, 1906 (42.86%) and Psorophora discrucians (Walker, 1856) (40.59%) were the most frequent species. No significant differences between quantities of Ps. champerico (t = -0.792; d.f. = 16; p = 0.43) and Ps. discrucians (t = 0.689; d.f. = 16; p = 0.49) obtained in riparian forest and near houses were observed, indicating similar conditions for crepuscular activity of these species in both environments. Psorophora champerico and Ps. discrucians responded (haematophagic activity) to environmental stimuli associated with the twilight hours differently in distinct habitats studied. The former species is registered for the first time in the Atlantic forest biome.

We analyzed the reproductive status, ovarian development, daily survival rate, and length of the gonotrophic cycle in females of Anopheles ( Kerteszia ) cruzii Dyar & Knab, to determine how these factors influence the risk of malaria transmission in the coastal region of the state of Paraná, southern Brazil. In the Palmito State Forest, Paranaguá, females were captured at dawn and dusk by aspiration, bimonthly from December 2006 through March 2007. A total of 2,268 females were captured, of which 454 were dissected. Of these, 48% were parous, 50% not reproductive, 73% in Christopher and Mer stages I and II, 23% in stages III to V, 55% nulliparous, 14% uniparous, and 11% had blood in their midgut. Daily survival was 0.24 ± 0.03 overall, 0.51 ± 0.04 for females captured at dusk, and 0.25 ± 0.03 for those captured at dawn. The Davidson equation for calculation of the gonotrophic cycle was inadequate for An. cruzii populations. Females captured at dusk had a higher survival rate than those from dawn, which means that more females of the dusk population enter the parasite extrinsic cycle. The continuous activity and abundance of A. cruzii in the Palmito State Forest suggests that the conditions are very favorable for its development, with a potential for participation in the protozoan's transmission cycle.

O objetivo da investigação foi analisar a variação da diversidade e abundância das espécies de Culicidae e sua relação com algumas variáveis ambientais, bem como estimar a taxa de paridade de Anopheles cruzii Dyar & Knab, 1908. O estudo foi desenvolvido em Floresta Ombrófila Densa da Mata Atlântica, localizada no Estado do Paraná, denominada de Floresta Estadual do Palmito. As capturas foram executadas quinzenalmente, de dezembro 2006 a março 2007, com a técnica de "aspiração menor", nos crepúsculos vespertino e matutino, iniciando antes dos crepúsculos e finalizando após os crepúsculos. Foram detectadas 25 espécies, sendo as mais abundantes, Anopheles cruzii (65,2%), Culex sachettae Sirivanakarn & Jacob, 1982 (11,2%) e Anopheles bellator Dyar & Knab, 1906 (8,5%). De acordo com análise de variância, ocorreu diferença significativa na freqüência entre os períodos crepusculares para seguintes espécies: Aedes scapularis (Rondone, 1848) (p = 0,03651), Coquillettidia chrysonotum (Peryassu, 1922) (p = 0,00795), Mansonia fonsecai (Pinto, 1932) (p = 0,00804), e Runchomyia theobaldi Lane & Cerqueira, 1934 (p = 0,01996). Não houve correlação significativa com a abundância das principais espécies capturadas e as médias dos fatores abióticos avaliados. A taxa de paridade de Anopheles cruzii atingiu média percentual de 48%, não existindo correlação entre a abundância e a taxa de paridade. O crepúsculo exerce influência no comportamento apetente das espécies de Culicidae. A comparação de similaridade entre os crepúsculos apontou para elevada semelhança da composição específica. Anopheles cruzii atingiu dominância nos períodos vespertino e matutino, sendo a diversidade de forma geral reduzida nestes períodos.

The aim of this investigation was to know the diversity and abundance of Culicidae associating with the climatic factors and obtaining the parity of Anopheles cruzii Dyar & Knab, 1908. The study was developed in a dense rain forest in Atlantic Forest, located in the State of the Paraná, named of Palmito State Park. The captures were performed two days in a month, during December 2006 to March 2007, occurring in the matutine and vespertine crepuscular periods. The captures were executed before twilight until after twilight. Twenty five species that belong to Culicidae were identified, the tree most abundant species were Anopheles cruzii (65.2%), Culex sachettae Sirivanakarn & Jacob, 1982 (11.2%) e Anopheles bellator Dyar & Knab, 1906 (8.5%). According to variance analysis, significant difference in frequency, was detected between crepuscular periods, for the following species: Aedes scapularis (Rondone, 1848) (p = 0. 03651), Coquillettidia chrysonotum (Peryassu, 1922) (p = 0. 00795), Mansonia fonsecai (Pinto, 1932) (p = 0. 00804), e Runchomyia theobaldi Lane & Cerqueira, 1934 (p = 0. 01996). The tree most captured species didn't show a significant correlation to the climatic factors. The rate parity of Anopheles cruzii was 48%. Didn't have correlation between the abundance with the rate parity. The twilight influences the behavior of Culicidae species. The similarity comparison between matutine and vespertine crepuscular periods revealed an elevated resemblance in the specific composition. A. cruzii was dominant specie in the crepuscular periods. The diversity in the crepuscular periods was considered decrease.

OBJETIVO: Conhecer a paridade e desenvolvimento ovariano da espécie Anopheles cruzii, durante os períodos estacionais. MÉTODOS: As capturas foram realizadas quinzenalmente, no período matutino, de abril/2004 a abril/2005, no Parque Estadual do Palmito, município de Paranaguá litoral do Estado do Paraná. Mosquitos adultos foram capturados usando a técnica pouso homem. As dissecções foram feitas utilizando-se a técnica de Detinova e de Polovodova e a avaliação do desenvolvimento folicular, segundo os critérios de Christophers e Mer. RESULTADOS: Foram dissecadas 208 fêmeas de Anopheles cruzii. A maioria das fêmeas dissecadas nas estações eram nulíparas. Sendo que 14,4% eram nulíparas com folículo além do estádio II de Christophers & Mer, o que evidencia o exercício da hematofagia previamente à primeira oviposição. Observou-se que as populações de Anopheles cruzii são constituídas de indivíduos jovens, talvez em razão da alta mortalidade de fêmeas paridas. CONCLUSÕES: A provável discordância gonotrófica das fêmeas dissecadas é importante do ponto de vista epidemiológico, considerando que a fêmea pode procurar mais de um hospedeiro para completar a maturação dos seus ovos.

OBJECTIVE: To determine the parity and ovarian development of Anopheles cruzii species during the seasons. METHODS: Collections were carried out fortnightly in the morning in the Palmito State Park in the municipality of Paranaguá, Southern Brazil, between April 2004 and April 2005. Adult mosquitoes were captured using human landing rate. Dissections were performed using Detinova's and Polovodova's methods and follicular development was assessed following Christophers and Mer's criteria. RESULTS: A total of 208 specimens of Anopheles cruzii were dissected. Most females dissected were nulliparous in the seasons; 14.4% of them were found to be nulliparous above Christophers and Mer's stage II, which shows previous blood meal prior to the first oviposition. It was observed that Anopheles cruzii populations comprised young mosquitoes, probably due to high mortality among parous females. CONCLUSIONS: The likely gonotrophic discordance is epidemiologically relevant because female mosquitoes can search for more than one host to complete the maturation of their eggs.

OBJETIVO: Conhecer a paridade e desenvolvimento ovariano da espécie Anopheles cruzii, durante os períodos estacionais. MÉTODOS: As capturas foram realizadas quinzenalmente, no período matutino, de abril/2004 a abril/2005, no Parque Estadual do Palmito, município de Paranaguá litoral do Estado do Paraná. Mosquitos adultos foram capturados usando a técnica pouso homem. As dissecções foram feitas utilizando-se a técnica de Detinova e de Polovodova e a avaliação do desenvolvimento folicular, segundo os critérios de Christophers e Mer. RESULTADOS: Foram dissecadas 208 fêmeas de Anopheles cruzii. A maioria das fêmeas dissecadas nas estações eram nulíparas. Sendo que 14,4% eram nulíparas com folículo além do estádio II de Christophers & Mer, o que evidencia o exercício da hematofagia previamente à primeira oviposição. Observou-se que as populações de Anopheles cruzii são constituídas de indivíduos jovens, talvez em razão da alta mortalidade de fêmeas paridas. CONCLUSÕES: A provável discordância gonotrófica das fêmeas dissecadas é importante do ponto de vista epidemiológico, considerando que a fêmea pode procurar mais de um hospedeiro para completar a maturação dos seus ovos.

OBJECTIVE: To determine the parity and ovarian development of Anopheles cruzii species during the seasons. METHODS: Collections were carried out fortnightly in the morning in the Palmito State Park in the municipality of Paranaguá, Southern Brazil, between April 2004 and April 2005. Adult mosquitoes were captured using human landing rate. Dissections were performed using Detinova's and Polovodova's methods and follicular development was assessed following Christophers and Mer's criteria. RESULTS: A total of 208 specimens of Anopheles cruzii were dissected. Most females dissected were nulliparous in the seasons; 14.4% of them were found to be nulliparous above Christophers and Mer's stage II, which shows previous blood meal prior to the first oviposition. It was observed that Anopheles cruzii populations comprised young mosquitoes, probably due to high mortality among parous females. CONCLUSIONS: The likely gonotrophic discordance is epidemiologically relevant because female mosquitoes can search for more than one host to complete the maturation of their eggs.

Os efeitos de temperaturas cíclicas no desenvolvimento, longevidade, ciclo gonadotrófico e número de ovos postos de Aedes albopictus Skuse foram analisados por meio de experimentos laboratoriais. Os experimentos foram conduzidos com mosquitos oriundos de Registro, SP e mantidos em insetário por dois anos. O desenvolvimento do inseto foi acompanhado desde o ovo até a emergência do adulto, a 25/18ºC e 27/20ºC e o adulto a 27/20ºC, ambos associados com fotoperíodo de 12h. Os ovos receberam dois tratamentos: (A) manutenção do volume da água; (B) troca periódica e completa da água. A alimentação sangüínea era oferecida diariamente aos mosquitos com interrupção quando o repasto era realizado, e retomada após a primeira oviposição. O desenvolvimento dos imaturos foi significativamente diferente sob os diferentes regimes de temperatura (P < 0,05), e a velocidade de desenvolvimento foi afetada positivamente pelo aumento da temperatura. A combinação do regime de temperaturas mais altas com a troca periódica e completa da água permitiu maior viabilidade dos ovos e encurtou o período de incubação. A longevidade dos adultos não foi diferente entre machos e fêmeas e a mortalidade foi regular ao passar do tempo. A comparação da longevidade do mosquito sob temperaturas constantes e cíclicas sugere que a menor temperatura do regime cíclico seja um fator limitante para a sobrevivência do mosquito. Esse fato pode ser um importante limitador da distribuição de A. albopictus por sugerir que o mosquito está restrito a ocupar áreas com temperaturas mínimas não muito inferiores a 20ºC.

The effects of cyclic temperatures on Aedes albopictus Skuse development, longevity, gonotrophic cycle and the number of oviposited eggs were assessed by means of laboratory experiments. The experiments were carried out with mosquitoes from Registro, São Paulo, Brazil, kept in insectary for two years. The development of the insect was followed from egg to adult emergence under 25/18ºC and 27/20ºC and adult stage under 27/20ºC, both associated with LD 12:12h. The eggs received two treatments: (A) maintenance of water volume; (B) periodical and complete change of water. Blood meal was offered daily and it was interrupted after haematophagy and restarted after first oviposition. The immature development was significantly different under the temperature regimes (P < 0.05) and the increased temperatures positively affected the development speed. The combination of higher temperatures regime and periodical and complete change of water increased the eggs viability and shortened the incubation time. Adult longevity was not different between males and females and the mortality was regular through the time. Comparing the mosquito longevity under constant and cyclic temperatures, it is suggested that the lowest temperature of the cyclic regime is a limiting factor for mosquito survival. This fact may limit the A. albopictus distribution range to areas where the minimal temperatures are not much bellow 20ºC.

Três fêmeas adultas de Aedes (Stegomyia) albopictus (Skuse) foram capturadas por meio de isca humana em área peridomiciliar de remanescente de Mata Atlântica na Praia de Itaguaçu, Ilha de São Francisco do Sul, litoral Norte de Santa Catarina.

Three adult females of Aedes (Stegomyia) albopictus (Skuse) were captured using a human bait in the surrounding dwelling area of the remaining rain forest in Itaguassu beach, island of São Francisco do Sul, northern coast of the state of Santa Catarina, Brazil.

Três fêmeas adultas de Aedes (Stegomyia) albopictus (Skuse) foram capturadas por meio de isca humana em área peridomiciliar de remanescente de Mata Atlântica na Praia de Itaguaçu, Ilha de São Francisco do Sul, litoral Norte de Santa Catarina.

Three adult females of Aedes (Stegomyia) albopictus (Skuse) were captured using a human bait in the surrounding dwelling area of the remaining rain forest in Itaguassu beach, island of São Francisco do Sul, northern coast of the state of Santa Catarina, Brazil.