Plant-based insect repellents: a review of their efficacy, development and testing

Plant-based repellents have been used for generations in traditional practice as a personal protection measure against host-seeking mosquitoes. Knowledge on traditional repellent plants obtained through ethnobotanical studies is a valuable resource for the development of new natural products. Recently, commercial repellent products containing plant-based ingredients have gained increasing popularity among consumers, as these are commonly perceived as “safe” in comparison to long-established synthetic repellents although this is sometimes a misconception. To date insufficient studies have followed standard WHO Pesticide Evaluation Scheme guidelines for repellent testing. There is a need for further standardized studies in order to better evaluate repellent compounds and develop new products that offer high repellency as well as good consumer safety. This paper presents a summary of recent information on testing, efficacy and safety of plant-based repellents as well as promising new developments in the field

Leitura crítica da mídia e narrativas audiovisuais: experiência de jovens no município mineiro de Mariana

As questões que envolvem a articulação entre mídia e educação perpassam o contexto contemporâneo, marcado pela forte presença das tecnologias de comunicação nos processos socioculturais. Há, portanto, a necessidade de promoção de leituras críticas da mídia. Nesse processo interativo, os questionamentos podem tensionar as práticas midiáticas a partir de projetos extensionistas voltados para esse fim. Assim, o presente estudo relata a metodologia, os resultados e desafios do projeto de extensão da Universidade Federal de Ouro Preto “Núcleo de Leitura Crítica da Mídia e Narrativas Audiovisuais”. O texto busca promover reflexões sobre a identificação de discursos e representações preponderantes, bem como a transformação das capacidades de comunicação dos jovens envolvidos

A crossover study to evaluate the diversion of malaria vectors in a community with incomplete coverage of spatial repellents in the Kilombero Valley, Tanzania

Malaria elimination is unlikely to occur if vector control efforts focus entirely on transmission occurring indoors without addressing vectors that bite outdoors and outside sleeping hours. Additional control tools such as spatial repellents may provide the personal protection required to fill this gap. However, since repellents do not kill mosquitoes it is unclear if vectors will be diverted from households that use spatial repellents to those that do not.; A crossover study was performed over 24 weeks in Kilombero, Tanzania. The density of resting and blood-engorged mosquitoes and human blood index (HBI) of malaria vector species per household was measured among 90 households using or not using 0.03 % transfluthrin coils burned outdoors under three coverage scenarios: (i) no coverage (blank coils); (ii) complete coverage of repellent coils; and (iii) incomplete coverage of repellent and blank coils. Mosquitoes were collected three days a week for 24 weeks from the inside and outside of all participating households using mosquito aspirators. Paired indoor and outdoor human landing collections were performed in three random households for six consecutive nights to confirm repellent efficacy of the coils and local vector biting times.; The main vectors were Anopheles arabiensis and Anopheles funestus (sensu stricto), which fed outdoors, outside sleeping hours, on humans as well as animals. Anopheles arabiensis landings were reduced by 80 % by the spatial repellent although household densities were not reduced. The HBI for An. arabiensis was significantly higher among households without repellents in the incomplete coverage scenario compared to houses in the no coverage scenario (Odds ratio 1.71; 95 % CI: 1.04-2.83; P = 0.03). This indicated that An. arabiensis mosquitoes seeking a human blood meal were diverted from repellent users to non-users. The repellent coils did not affect An. funestus densities or HBI.; Substantial malaria vector activity is occurring outside sleeping hours in the Kilombero valley. Repellent coils provided some protection against local An. arabiensis but did not protect against local (and potentially pyrethroid-resistant) An. funestus. Pyrethroid-based spatial repellents may offer a degree of personal protection, however the overall public health benefit is doubtful and potentially iniquitous as their use may divert malaria vectors to those who do not use them

The Effect of Deltamethrin-Treated Net Fencing Around Cattle Enclosures on Outdoor-biting Mosquitoes in Kumasi, Ghana.

Classic vector control strategies target mosquitoes indoors as the main transmitters of malaria are indoor-biting and -resting mosquitoes. However, the intensive use of insecticide-treated bed-nets (ITNs) and indoor residual spraying have put selective pressure on mosquitoes to adapt in order to obtain human blood meals. Thus, early-evening and outdoor vector activity is becoming an increasing concern. This study assessed the effect of a deltamethrin-treated net (100 mg/m(2)) attached to a one-meter high fence around outdoor cattle enclosures on the number of mosquitoes landing on humans. Mosquitoes were collected from four cattle enclosures: Pen A - with cattle and no net; B - with cattle and protected by an untreated net; C - with cattle and protected by a deltamethrin-treated net; D - no cattle and no net. A total of 3217 culicines and 1017 anophelines were collected, of which 388 were Anopheles gambiae and 629 An. ziemanni. In the absence of cattle nearly 3 times more An. gambiae (p<0.0001) landed on humans. The deltamethrin-treated net significantly reduced (nearly three-fold, p<0.0001) culicine landings inside enclosures. The sporozoite rate of the zoophilic An. ziemanni, known to be a secondary malaria vector, was as high as that of the most competent vector An. gambiae; raising the potential of zoophilic species as secondary malaria vectors. After deployment of the ITNs a deltamethrin persistence of 9 months was observed despite exposure to African weather conditions. The outdoor use of ITNs resulted in a significant reduction of host-seeking culicines inside enclosures. Further studies investigating the effectiveness and spatial repellence of ITNs around other outdoor sites, such as bars and cooking areas, as well as their direct effect on vector-borne disease transmission are needed to evaluate its potential as an appropriate outdoor vector control tool for rural Africa

Effects of larval exposure to sublethal doses of ivermectin on adult fitness and susceptibility to ivermectin in Anopheles gambiae s.s.

Background: The effects of ivermectin (endectocide) on mosquito survival make it a potential new malaria vector control tool. The drug can be administered to mosquito disease vectors through blood hosts that include humans and livestock. Its increased use may cause contamination of larval habitats, either directly through livestock excreta or indirectly through leaching or run-off from contaminated soil, albeit in sublethal doses. However, the effects of such exposure on immature stages and the subsequent adults that emerge are poorly understood. This study was undertaken to evaluate the impact of ivermectin exposure on Anopheles gambiae s.s. larvae and its effects on fitness and susceptibility to ivermectin in the emerging adults. Methods: Laboratory-reared An. gambiae s.s. (Kilifi strain) larvae were exposed to five different ivermectin concentrations; 0, 0.00001, 0.0001, 0.001, and 0.01 ppm, and larval survival was monitored to determine the appropriate sub-lethal dose. Concentrations with survival > 50% (0.00001 and 0.0001 ppm) were selected and used as the sub-lethal doses. The fecundity, fertility, and susceptibility to ivermectin of adults emerging after larval exposure to the sub-lethal doses were examined. Results: Overall, exposure of An. gambiae s.s. aquatic stages to ivermectin caused a dose-dependent reduction in larval survival irrespective of the stage at which the larvae were exposed. Exposure to ivermectin in the larval stage did not have an effect on either the number of eggs laid or the hatch rate. However, exposure of first/second-instar larvae to 0.0001 ppm and third/fourth-instar larvae to 0.001 ppm of ivermectin reduced the time taken to oviposition. Additionally, exposure to ivermectin in the larval stage did not affect susceptibility of the emerging adults to the drug. Conclusions: This study shows that contamination of larval habitats with ivermectin affects An. gambiae s.s. larval survival and could potentially have an impact on public health. However, there are no carry-over effects on the fecundity, fertility, and susceptibility of the emerging adults to ivermectin. In addition, this study shows that environmental exposure to ivermectin in the larval habitats is unlikely to compromise the efficacy of ivermectin in the emerging adults

Singularities of gender in the representations of attachmentduring pre-school time

Visando identificar diferenças individuais no modo como as crianças encenam uma variedade de situaçõesrelacionadas com a vinculação, o Attachment Story Completion Task-ASCT (Bretherton. Ridgeway, &Cassidy, 1990) tem sido utilizado em diferentes culturas, tanto com amostras clínicas como normativas,sendo uma das metodologias de narrativas mais utilizadas durante o período pré-escolar. Todavia, umponto problemático da sua utilização prende-se com o facto de alguns estudos reportarem especificidadesao nível dos perfis narrativos evidenciados por meninos e meninas o que, do ponto de vista da Teoria daVinculação, não seria de esperar. O ASCT foi aplicado a 252 crianças em idade pré-escolar (M=62; DP=15,1) tendo as narrativas sido analisadas através de uma escala contínua de segurança. Não foi encontradanenhuma relação significativa entre a segurança das narrativas e o Q.I. verbal dos participantes. Nasrespostas ao ASCT verificou-se uma diferença em função do género [F(1, 253)=11,8, p<0,01], com ashistórias produzidas pelas raparigas, em média, a receberem pontuações mais elevadas na dimensãosegurança. Várias hipóteses teóricas são exploradas para explicar os perfis encontrados e, partindo daideia avançada por Oppenheim (1997) de que a aplicação deste tipo de metodologias representa umasituação indutora de ansiedade para a criança, é dado destaque à tese evolutiva proposta por Taylor et al.(2000) que afirma existir divergências ao nível das estratégias de regulação emocional tendencialmenteadoptadas pelos dois sexos em situações de stress e de conforto interpessoal.Palavras-chave:, ,.Abstract Attempting to identify individual differences in the way children tend to enact a variety of attachment-related scenarios, the Attachment Story Completion Task(Bretherton, Ridgeway, & Cassidy, 1990) hasbeen used in various cultures, both with normative and clinical samples, being considered a key narrativemethodology in the field. Yet, a controversial question regarding its use is the fact that some studiesunexpectedly report gender differences. Attachment Theory does not consider gender a relevant variablein the organization (quality) of attachment relationships. Gender is also not relevant when mental repre-sentations regarding such relationships are considered. Two hundred fifty two pre-schoolers (M=62;DP=15.1) participated in this study. Children’s narratives were coded according to a continuous securityscale, and no correlation was found with Verbal I.Q. Gender differences were found [F(1.253)=11.8, p<.01]with girls, on average, having higher scores than boys in all stories. Different reasons for children’s playbehavior were discussed, considering also that this kind of methodology can be a stressful situation to thechild (Oppenheim, 1997). Special emphasis was given to Taylor et al. (2000) bio-evolutionist theory thatexplores the use of different strategies to cope with stress used by both genders.info:eu-repo/semantics/publishedVersio

Singularidades de género nas representações de vinculação durante o período pré-escolar

Visando identificar diferenças individuais no modo como as crianças encenam uma variedade de situações relacionadas com a vinculação, o Attachment Story Completion Task-ASCT (Bretherton. Ridgeway, & Cassidy, 1990) tem sido utilizado em diferentes culturas, tanto com amostras clínicas como normativas, sendo uma das metodologias de narrativas mais utilizadas durante o período pré-escolar. Todavia, um ponto problemático da sua utilização prende-se com o facto de alguns estudos reportarem especificidades ao nível dos perfis narrativos evidenciados por meninos e meninas o que, do ponto de vista da Teoria da Vinculação, não seria de esperar. O ASCT foi aplicado a 252 crianças em idade pré-escolar (M=62; DP= 15,1) tendo as narrativas sido analisadas através de uma escala contínua de segurança. Não foi encontrada nenhuma relação significativa entre a segurança das narrativas e o Q.I. verbal dos participantes. Nas respostas ao ASCT verificou-se uma diferença em função do género [F(1, 253)=11,8, pAttempting to identify individual differences in the way children tend to enact a variety of attachmentrelated scenarios, the Attachment Story Completion Task (Bretherton, Ridgeway, & Cassidy, 1990) has been used in various cultures, both with normative and clinical samples, being considered a key narrative methodology in the field. Yet, a controversial question regarding its use is the fact that some studies unexpectedly report gender differences. Attachment Theory does not consider gender a relevant variable in the organization (quality) of attachment relationships. Gender is also not relevant when mental representations regarding such relationships are considered. Two hundred fifty two pre-schoolers (M=62; DP=15.1) participated in this study. Children's narratives were coded according to a continuous security scale, and no correlation was found with Verbal I.Q. Gender differences were found [F(1.253)=11.8, p<.01] with girls, on average, having higher scores than boys in all stories. Different reasons for children's play behavior were discussed, considering also that this kind of methodology can be a stressful situation to the child (Oppenheim, 1997). Special emphasis was given to Taylor et al. (2000) bio-evolutionist theory that explores the use of different strategies to cope with stress used by both genders

Representações de vinculação na infância: Competência verbal, estabilidade e mudança

Visando identificar diferenças individuais no modo como as crianças encenam uma variedade de situações relacionadas com a vinculação, o Attachment Story Completion Task (ASCT, Bretherton & Ridgeway, 1990) tem sido utilizado em diferentes culturas, sendo uma das metodologias narrativas de completamento de histórias mais utilizadas durante o período pré-escolar. Não obstante o vasto reconhecimento do seu valor, tanto clínico como empírico, mais estudos revelam-se indispensáveis para confirmar a validade discriminativa do ASCT face a medidas de competência verbal, bem como para clarificar alguns aspectos relacionados com a sua fiabilidade. Procurando contribuir para uma melhor compreensão da utilização do instrumento na população portuguesa, o presente estudo debruça-se especificamente sobre a potencial influência da idade e do Q.I. verbal nas respostas dadas pelas crianças. O ASCT foi aplicado a 159 crianças em idade pré-escolar e escolar (M=66.11, DP=9.96),tendo o desempenho dos sujeitos ao longo da tarefa sido analisado através de uma escala contínua de segurança, por investigadores independentes, previamente treinados. Os valores de segurança (quer história a história, quer no conjunto das histórias) não apresentaram associações relevantes com nenhuma das variáveis sócio-demográficas consideradas, nem com a idade dos participantes. Foi, no entanto, encontrada uma associação positiva, de fraca intensidade com o Q.I. verbal, estimado através da WPPSI-R [Wechsler, 1989) [r=.16, p(unilateral)<.05]. A estabilidade da medida foi explorada numa sub-amostra de 34 sujeitos, após um intervalo temporal de, aproximadamente, 11 meses. Verificou-se que, embora haja uma tendência para o desempenho global dos sujeitos ser avaliado, em termos da média grupal, de forma significativamente mais elevada [t(33)=2.50, p(unilateral)<.01, d=.49], quando avaliada intra-sujeitos, a segurança mostra-se moderadamente estável (r=.33, p<.05, n=34). Finalmente, foram encontradas evidências que sugerem influências recíprocas, ao longo do desenvolvimento, entre aspectos associados à segurança das representações e capacidade verbal