Daniel Marucci

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 9- Synanthropy and epidemiological vector role of Aedes scapularis in South-Eastern Brazil

Behaviour comparisons of Aedes scapularis and Ae. serratus are presented. Results were obtained by sampling Aedes adult mosquitoes at several places in the rural anthropic environment in the Ribeira Valley region of S. Paulo State, Brazil. Aedes dominance was shared by those two species, but Ae. scapularis showed a clear tendency to frequent the modified environment, while Ae. serratus was to be found in the more preserved ones, here represented by the vestigial patchy forests. Regarding the open cultivated land and the dwelling environments, Ae. scapularis preponderates. Considering the regional development phases, this mosquito showed a remarkable increase in the modified environment differently from Ae. serratus that underwent a considerable decrease in migrating from the forest to the anthropic environment. As a consequence of these results it is reasonable to conclude that Ae. scapularis may be considered as an epidemiologically efficient vector and that it quite probably played this role in the Rocio encephalitis and other arbovirus epidemics.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 4 - Survey of resting adults and synanthropic behaviour in South-Eastern, Brazil

Resting adults Culicidae were collected from January 1992 through January 1993 in several habitats of the Ribeira Valley region. The diversity of species found among them suggested that the vegetation remaining within human settlements favored the survival and the population increase of some mosquitoes. Among there are: Ae. scapularis, Ae. serratus, Cx. (Culex), Cx. nigripalpus and Cx. (Melanoconion) such as Cx. ribeirensis. That preservation role may be attributed to the rearing of livestock and the consequent increase in the number of blood sources. These species may be classified as hemisynanthropes and Cx. oedipus apparently evolving to the eusynanthropic status. On the other hand, An. cruzii showed an asynanthropic behaviour, with a low degree of survival in the modified human environment. Epidemiological implications of the data are mentioned.Resting adults Culicidae were collected from January 1992 through January 1993 in several habitats of the Ribeira Valley region. The diversity of species found among them suggested that the vegetation remaining within human settlements favored the survival and the population increase of some mosquitoes. Among there are: Ae. scapularis, Ae. serratus, Cx. (Culex), Cx. nigripalpus and Cx. (Melanoconion) such as Cx. ribeirensis. That preservation role may be attributed to the rearing of livestock and the consequent increase in the number of blood sources. These species may be classified as hemisynanthropes and Cx. oedipus apparently evolving to the eusynanthropic status. On the other hand, An. cruzii showed an asynanthropic behaviour, with a low degree of survival in the modified human environment. Epidemiological implications of the data are mentioned.

Microhabitats de Aedes albopictus (Skuse) na região do Vale do Paraíba, Estado de São Paulo, Brasil

The objective of this study was the determination of extent of the spatial distribution of Aedes albopictus in the Paraiba River Valley, State S. Paulo, Brazil. Thus, collections of larvae and pupae mosquitoes were carried out at six sites distributed along a transection with a 10-km extension. The target was the tree-holes but artificial containers were also used in this investigation. Aedes terrens and Ae. albopictus were the only species of genus Aedes present in the tree-holes mentioned. The segregation of seven species of the tree-hole community was undertaken in the light of macrohabitat and microhabitat features. Thus, the distribution of Ae. albopictus was found to cover the rural, rural-urban and urban zones, but the rural-urban held the preference. Ae. albopictus never present in the residual and primary forest. The favorable factor to infestation with Ae. albopictus in the Paraiba Valley seems to have been the large number of natural niches made vacant by human influence. The rain has been important in the production of larvae and pupae, but the rainfall period does not coincide with the maximum production on them. The tree-holes whose volume exceeded 600 ml were the most productive breeding places. The abundance of these two stages occurs in the summer and autumn. However, the highest peak was observed in the months of March and April. These seasonal variations were found to be common in both the bamboo trap and the artificial container. The temperature data suggest a limit of from 17 to 23 degrees C for the best development of larvae. In the light of this, the strain of Ae. albopictus studied seems to have originated in tropical Asia. Just as happened with Ae. aegypti it may become an important epidemiological vector for the dengue fever and provide links for yellow fever transmission in Brazil.

Preferências alimentares de mosquitos Culicidae no Vale do Ribeira, São Paulo, Brasil

Sao apresentados os resultados obtidos na identificacao do sangue ingerido por culicideos ingurgitados coletados em varios ambientes rurais de cinco localidades do Vale do Ribeira, Estado de Sao Paulo (Brasil). O maior rendimento, que representou a quase totalidade dos especimens coletados, foi obtido mediante o emprego da aspiracao e das redes manuais. Foi possivel identificar a origem de 1.444 repastos sanguineos. Os Aedes apresentaram predominância de positividade para mamiferos. Ae. scapularis mostrou preferencia por hospedeiros de grande porte representados por bovinos e equinos. Ae. serratus alimentou-se tambem em aves. Com excecao da elevada antropofilia de Cx. quinquefasciatus, os demais representantes de Cx. (Culex) revelaram-se apreciavelmente ornitofilos. Em conjunto, Cx. (Melanoconion) mostrou o mais amplo espectro de hematofagia, que incluiu anfibio, ave, mamiferos e reptil. Cx. ribeirensis e Cx. sacchettae apresentaram resultados que sugerem alguma preferencia por mamiferos. A antropofilia distribuiu-se por varias especies destacando-se Ae. scapularis, Cx. sacchettae e Cx. ribeirensis que a apresentaram nas coletas efetuadas no intradomicilio. A influencia da densidade de hospedeiros no ambiente modificado fez-se sentir em relacao a primeira dessas tres especies, para as quais as evidencias obtidas sugerem que estejam evoluindo no sentido da domiciliacao.Sao apresentados os resultados obtidos na identificacao do sangue ingerido por culicideos ingurgitados coletados em varios ambientes rurais de cinco localidades do Vale do Ribeira, Estado de Sao Paulo (Brasil). O maior rendimento, que representou a quase totalidade dos especimens coletados, foi obtido mediante o emprego da aspiracao e das redes manuais. Foi possivel identificar a origem de 1.444 repastos sanguineos. Os Aedes apresentaram predominância de positividade para mamiferos. Ae. scapularis mostrou preferencia por hospedeiros de grande porte representados por bovinos e equinos. Ae. serratus alimentou-se tambem em aves. Com excecao da elevada antropofilia de Cx. quinquefasciatus, os demais representantes de Cx. (Culex) revelaram-se apreciavelmente ornitofilos. Em conjunto, Cx. (Melanoconion) mostrou o mais amplo espectro de hematofagia, que incluiu anfibio, ave, mamiferos e reptil. Cx. ribeirensis e Cx. sacchettae apresentaram resultados que sugerem alguma preferencia por mamiferos. A antropofilia distribuiu-se por varias especies destacando-se Ae. scapularis, Cx. sacchettae e Cx. ribeirensis que a apresentaram nas coletas efetuadas no intradomicilio. A influencia da densidade de hospedeiros no ambiente modificado fez-se sentir em relacao a primeira dessas tres especies, para as quais as evidencias obtidas sugerem que estejam evoluindo no sentido da domiciliacao.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 2 - Immature stages research at a rice irrigation system location in South-Eastern Brazil

A relation between a rice irrigation system and mosquito breeding was established in a study undertaken at the Ribeira Valley Experimental Station, from January through December 1992. Flooding favoured Anopheles (Nyssorhynchus) and Culex (Melanoconion) species, while empty paddies condition were propitious to Aedes scapularis and Culex (Culex) species. Compared with a more primitive area of the same region, several species showed high a degree of adaptation to the anthropic environment. Among them, Anopheles albitarsis, a potential malaria vector that breeds in the irrigation system, has shown immature stage production thirteen times higher than at the natural breeding sites. In addition, Ae. scapularis, An. oswaldoi, Cx. bastagarius, and Cx. chidesteri presented high levels of synanthropy.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 3- Survey of adult stages at the rice irrigation system and the emergence of Anopheles albitarsis in South-Eastern, Brazil

A study of adult Culicidae ecology was carried out from January 1992 through January 1993 at the rice irrigation system of the Ribeira Valley Experimental Station. The adaptation of Anopheles albitarsis to the anthropic environment became evident through the adult collections made at its various habitats represented by the irrigation system and the edge of the residual pond, as well as at those made within the local patchy residual woods. Other potential disease vectors were prevalent in the irrigated system too. There were Aedes scapularis, Culex nigripalpus and Cx. ribeirensis that were collected at various habitats. Remarkable differences among their prevalences were obtained such as between the natural forest and anthropic environments. In the former An. albitarsis was practically non-existent, thus suggesting that it might be considered as eusynathropic. As the populations of other species seemed to increase in the anthropic environment, they may be regarded as hemisynanthropes. Observations suggest the hypothesis that the development of irrigated land may be a factor in the emergence of An. albitarsis, and some other species, as well as the possibility of an increase in the transmission of mosquito-borne diseases such as malaria.

Preferências alimentares e domiciliação de mosquitos Culicidae no Vale do Ribeira, São Paulo, Brasil, com especial referência a Aedes scapularis e a Culex (Melanoconion)

New results on blood-meal identification and the environmental distribution of mosquitoes collected in four different Ribeira Valley (S. Paulo State, Brazil) environments, during the period February to November 1986, are presented. Sources of 651 blood-meals were identified. The preference of Ae. scapularis for large mammals, chiefly cattle, horse and even man, was confirmed. Data suggests that a similar behavioral pattern is presented by Cx. ribeirensis. Both mosquitoes seem to be strongly attracted by peridomiciliar blood sources represented by domestic animals sheltered in that environment. Nevertheless, the female of Ae. scapularis females may use the extradomiciliary environment, represented by residual forests, as resting place in the same way as it uses the peridomiciliary one. The data confirm the clear tendency of both Ae. scapularis and Cx. ribeirensis to adapt to the man-made environment and thus the evolution towards domiciliation in the behavior of these mosquitoes. Other culicids, such as An. bellator, An. cruzii and Cq. chrysonotum, were collected practically only by the use of human bait. For An. cruzii the number of females collected by this method represented 31.6% of the female total collected during this project. Some data about other species are given, and the need for further researches about Culex (Melanoconion) species is emphasized.Apresentam-se novos dados sobre a identificacao do sangue ingerido por culicideos ingurgitados e coletados em quatro localidades do Vale do Ribeira, Estado de Sao Paulo (Brasil), no periodo de fevereiro a novembro de 1986, e que ja tinham sido sede de observacoes anteriores. Sao fornecidos dados sobre a distribuicao de algumas especies relacionadas ao tipo de ambiente. Focalizam-se Ae. scapularis e representantes de Culex (Melanoconion), principalmente Cx. ribeirensis e Cx. sacchettae. Foi possivel a identificacao de 651 repastos sanguineos. Confirmou-se a preferencia de Ae. scapularis por mamiferos de grande porte representados por bovinos, equinos e o proprio homem, tendo reagido a todos os anti-soros testados, com excecao do correspondente a animais de sangue frio representados por anfibio. Cx. ribeirensis revelou resultados que sugerem possivel preferencia por mamiferos. As duas especies supracitadas mostram tendencia nitida para adaptacao ao ambiente modificado pelo homem e capacidade de evolucao de seus habitos de possivel domiciliacao. Quanto aos outros culicideos, as coletas de An. bellator, An. cruzii e Cq. chrysonotum limitaram-se a isca humana que a segunda dessas especies rendeu 31,6% do total de femeas capturadas.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 11 - Biting activity and blood-seeking parity of Anopheles (Kerteszia) in South-Eastern Brazil

An. (Ker.) cruzii and An. (Ker.) bellator were monitored by the use of human bait and Shannon trap collections during a one-year period in 1994. Indoor and outdoor collections were made on human bait and inside the forest environment a Shannon trap was used. Both were undertaken in the evening crepuscular period. Results showed a greater abundance of An. cruzii in the forest, where as An. bellator was more abundant in the domiciliary environment. Through the application of the Polovodova method an age grading was established. Computing the parous and nulliparous females with Christophers Stage III and above, more than 30.0% of blood-seeking specimens of both anophelines had had a previous blood meal. The higher abundance of An. bellator as compared with that of An. cruzii in the domiciliary environment may be explained by the influence of the neighboring low-lying coastal islands of the estuary system.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 10- survey of adult behaviour of Culex nigripalpus and other species of Culex (Culex) in South-Eastern Brazil

A survey of adult behaviour of Culex (Culex) species was carried out from August 1992 through December 1993 in a human modified (anthropic) environment in the Ribeira Valley, S. Paulo State, Brazil. Culex nigripalpus dominated the catches at several sites and its tendency to increase in the anthropic environment became quite clear. Nevertheless no high level of synanthropy was demonstrated. So it seems that the mosquito may have a restricted role in natural arbovirus cycles. Nonetheless, Cx. nigripalpus must be considered a potential vector of arboviruses, especially St. Louis encephalitis virus outside dwellings.

Freqüência domiciliar e endofilia de mosquitos Culicidae no Vale do Ribeira, São Paulo, Brasil

Results of mosquito collections in two Ribeira Valley localities are presented. These places represents environments highly modified by agrarian and cattle raising activities. The collections were made by the aspiration method, in the search for resting mosquitoes, in all the domiciliary and peridomiciliary compounds, in the early morning. The use of the diversity index and similarity quotient on communities such as these that are tropically related gives some insight into resources and their distribution. So they are considered of great value for the endophily studies. Data obtained suggest that there is some degree of endophilic evolution in Ae. scapularis, Cx. ribeirensis and Cx. sacchettae. This behavior is subject to the influence of some extrinsic factors such as the density of cattle or other large domestic animals, and human behaviour in the management of the environment.Results of mosquito collections in two Ribeira Valley localities are presented. These places represents environments highly modified by agrarian and cattle raising activities. The collections were made by the aspiration method, in the search for resting mosquitoes, in all the domiciliary and peridomiciliary compounds, in the early morning. The use of the diversity index and similarity quotient on communities such as these that are tropically related gives some insight into resources and their distribution. So they are considered of great value for the endophily studies. Data obtained suggest that there is some degree of endophilic evolution in Ae. scapularis, Cx. ribeirensis and Cx. sacchettae. This behavior is subject to the influence of some extrinsic factors such as the density of cattle or other large domestic animals, and human behaviour in the management of the environment.