Carlos Fernando Salgueirosa de Andrade

Susceptibilidade larval de populações de Aedes aegypti e Culex quinquefasciatus a inseticidas químicos

OBJECTIVE To evaluate the susceptibility to chemical insecticides of Culex quinquefasciatus and Aedes aegypt larvae from areas subjected to control treatments or not. METHODS Bioassays for diagnostic concentration and multiple concentration were performed for organophosphate and pyrethroid insecticides according to World Health Organization parameters. The susceptibility was assessed for mosquito larvae collected from an area not subjected to chemical control (Campinas, State of S o Paulo, SP) and from other areas (Campo Grande, Mato Grosso do Sul, MS, and Cuiabá, Mato Grosso, MT), in Brazil, subjected to such treatments. RESULTS Tests for Culex quinquefasciatus larvae from Campinas, SP, allowed suspicion of resistance to cypermethrin and gave evidence of resistance to cyfluthrin. Larvae of this species collected in Campo Grande, MS, and Campinas, SP, presented resistance to temephos. For the colony from the latter locality, the following resistance rates were established: RR50=6.36 and RR95=4.94, in relation to a standard susceptible strain. Moreover, tests for Aedes aegypti showed similar susceptibility to temephos for a field population from Cuiabá, MT, and a laboratory population. CONCLUSIONS The results indicate resistance of Culex quinquefasciatus to organophosphate and pyrethroid insecticides and make evident the need for evaluation and monitoring of the efficiency of insecticides to be used in mosquito control programs.

Avaliação de uma intervenção educativa na prevenção da dengue

O objetivo do presente trabalho foi o de avaliar uma abordagem educativa para a prevencao da dengue em Campinas. A abordagem foi baseada em um curso de 20 horas para professores de ensino fundamental, seu subsequente trabalho com os alunos, e destes para seus familiares. No curso foram fornecidos instrumentos didaticos, para a identificacao de mosquitos e armadilhas para vigilância. Foram fornecidos tres agentes biologicos para demonstracoes e uso, como agentes de controle de mosquitos capturados nas armadilhas. Foi avaliada a reducao ou eliminacao de sitios de criacao dos vetores da dengue para os ambientes escolares e para uma amostra das residencias dos estudantes, ate um ano depois do curso. Foi observado um esperado aumento do conhecimento, mas um aumento menos significativo nos ambientes escolares livres de sitios potenciais de criacao do mosquito.

Malpighian tubule polytene chromosomes of Culex quinquefasciatus (Diptera, Culicinae)

Dipteran polytene chromosomes provide an excellent model for understanding in species complexes, as well as for structural and functional cytogenetics. The status of species in the Culex pipiens complex is controversial and the use of polytene chromosomes for cytogenetic analysis in the subfamily Culicinae has been difficult because of methodological problems. In this study, Malpighian tubule polytene chromosomes were obtained from young (0 to 12 h, 20 C) and old (20 to 42 h, 28 C) laboratory-bred C. pipiens quinquefasciatus pupae. The chromosome maps for this species were constructed and compared with published data for C. pipiens pipiens and C. p. quinquefasciatus. Although the banding patterns were conserved between subspecies, analysis of the structural variations in the bands and interbands revealed differences apparently related to the physiological stage and ecogeographical strain. The organization of the centromeric regions in larval and pupal chromosomes showed greater similarity to each other than did those of pupal and adult chromosomes. The use of pupal polytene chromosomes for in situ hybridization with vector competence probes is discussed.

Alguns aspectos socioeconômicos relacionados a parasitoses intestinais e avaliação de uma intervenção educativa em escolares de Estiva Gerbi, SP

Among the students attended by the City Education Secretary of Estiva Gerbi, 11.5% presented enteroparasites. This prevalence could be related to socioeconomic aspects. Accordingly we conducted a workshop on intestinal parasites with the objective of informing and discussing related aspects in combination with medical treatment. Students were evaluated from the Alaíde R. Batista School, which attends children up to 4 years old and had the highest (23.5%) level of parasitism. Reevaluation two years after the workshop showed that the prevalence of enteroparasites in the treated students had decreased to 6.6%, but considering the school as a whole the prevalence was still 23.3%, due to the enrolling of new students. It was concluded that educational programs are only effective when integrated to a complete and continuous process of education, control and eradication of enteroparasitosis.

A technique for preparing polytene chromosomes from Aedes aegypti (Diptera, Culicinae)

Polytene chromosome preparations were obtained from larval, pupal and adult female Malpighian tubules of Aedes aegypti. The Malpighian tubules of the pupae (0-4 h old) from larvae reared at 20 C provided the best cytogenetic analysis. The interaction of nucleic acids and proteins that influence the spreading of the chromosomes could be reduced with the preparation technique of the sheets submitted to a stronger treatment starting with the hypotony of tissue and successive bathings with acetic acid. A simple technique should facilitate molecular cytogenetics used in the location of resistance and vector competence genes.

Methods for field detection of resistance to temephos in simuliids. Larval esterase level and topical application of the insecticide to adults

Two practical field methods for indirect detection of simuliid populations resistant to temephos are proposed. The first is based on high esterase activity in resistant larvae and involves adaptations of a filter paper test in which faintly stained spots indicate susceptible populations and strongly stained ones reveal populations resistant to temephos. The second is based on the resistance to the larvicide when adults are topically exposed, and involves the use of diagnostic doses obtained by the comparison between the LD50 for susceptible and resistant populations. The relevance of such methods is discussed in order to help resistance detection in Simulium pertinax Kollar control programmes.

Resistência a inseticidas em populações de Simulium (Diptera, Simuliidae)

Populations of Simulium (Chirostilbia) pertinax Kollar, 1832 from Southern and Southeastern States of Brazil were analyzed for temephos susceptibility considering control historical information and possible resistance. In situ bioassays were carried out for populations from the states of Paraná (Tibaji and Rolândia), Rio de Janeiro (Muriqui) and São Paulo (Barra do Una, Ilhabela and Morungaba). The populations were characterized as susceptible (S) or resistant (R) by submitting larvae in the last instars to an operational concentration (0.1ppm a.i./10min) of temephos (Abate 500E) as diagnostic. The possible mechanisms for the organophosphorus resistance development are discussed considering old and new control strategies.

Evaluation of Electronic Mosquito-Repelling Devices Using Aedes albopictus (Skuse) (Diptera: Culicidae)

The mosquito-repelling devices Anti-Pic®, Mosquito Repeller® DX-600 and Bye-Bye Mosquito® were evaluated in boxes for experimentation by exposing human hands to Aedes albopictus (Skuse) adults. Two sets of tests were performed based on 15 min. expositions. In the first set both hands were introduced in the box, one of them holding the device on. In the second set only one hand was introduced each time, holdind the device on or off. The devices failed to show efficiency in both evaluations. A seemingly 30.3% repellency due to Anti-Pic® in the first set of experiments was not confirmed in the second set. It was discussed the value of such devices for dengue prevention.

Búsqueda de xifidiocercarias (Trematoda) en moluscos de agua dulce recolectados en nueve municipios del Estado de São Paulo, Brasil

Xiphidiocercariae, aquatic larval stages of some trematodes are considered a potential instrument for biological control of mosquitoes. In this study we evaluated its natural occurrence in Campinas region and two places in Vale do Ribeira (Registro and Miracatu), Sao Paulo State. Snails were obtained from fresh water collections from September 1996 to February 1999. The species collected were Lymnaea columella, Physa marmorata, Biomphalaria tenagophila, Biomphalaria sp., Drepanotrema cimex, D. lucidum and Drepanotrema sp. Fasciola hepatica, xiphidiocercariae (Haematoloechidae) and echinostomatid cercariae were detected in the lymnaeids snails from Miracatu, SP. In the same locality were found planorbids snails parasitized by furcocercariae, echinostomatid cercariae and xiphidiocercariae. The xiphidiocercariae found in the planorbids were different from those obtained from lymnaeids. One Biomphalaria sp. infected with furcocercariae was found in Louveira, SP. In the ROSA place (Campinas, SP) an individual of Biomphalaria sp. and one of L. columella were found infected by the furcocercariae and echinostomatid cercariae, respectively. In the place UNI-I, in Campinas, one L. columella was infected by furcocercariae. Double infection in snails from Miracatu was also observed

Experimental Infection of Aedes albopictus (Diptera: Culicidae) Larvae with the Xiphidiocercariae of a Hematolechid

Aedes albopictus larvae were exposed, either individually or in groups, to different concentrations of xiphidiocercariae of Haematoloechus sp. for parasitological studies. It was observed the acute lethal effect and some aspects of the host-parasite relationship, such as delay or progress in the host life cycle, the number and location of the metacercariae in the host, adult host malformations and the amount of metacercariae required to cause death. A delay in the cycle and a high mortality rate was in general observed. Inside the larvae, the metacercariae were found predominantly in the thorax, abdominal segments and in the head, along with a reduced number in the anal lobe and cervix. It was shown that in addition to the quantity of metacercariae present, their location in the larvae was also relevant in the determination of mortality and anomalies. Malformed adults developed from larvae containing from one to three metacercariae.