Morfometria e morfologia comparadas de ovos de Anopheles aconitus formas B e C à microscopia eletrônica de varredura

Comparative morphometric and morphological studies of eggs under scanning electron microscope (SEM) were undertaken in the three strains of two karyotypic forms of Anopheles aconitus, i.e., Form B (Chiang Mai and Phet Buri strains) and Form C (Chiang Mai and Mae Hong Son strains). Morphometric examination revealed the intraspecific variation with respect to the float width [36.77 ± 2.30 µm (Form C: Chiang Mai strain) = 38.49 ± 2.78 µm (Form B: Chiang Mai strain) = 39.06 ± 2.37 µm (Form B: Phet Buri strain) >; 32.40 ± 3.52 µm (Form C: Mae Hong Son strain)] and number of posterior tubercles on deck [2.40 ± 0.52 (Form B: Phet Buri strain) = 2.70 ± 0.82 (Form B: Chiang Mai strain) ; 32,40 ± 3,52 µm (Forma C: linhagem Mae Hong Son)] e número de tubérculos posteriores sobre a superfície livre [2,40 ± 0,52 (Forma B: linhagem Phet Buri) = 2,70 ± 0,82 (Forma B: linhagem Chiang Mai) < 3,10 ± 0,32 (Forma C: linhagem Chiang Mai) = 3,20 ± 0,42 (Forma C: linhagem Mae Hong Son)] embora a topografia de superfície dos ovos entre as três linhagens de duas formas cariotípicas tenham sido morfologicamente semelhantes

The Discriminative Infection of Dengue Virus in Aedes aegypti at Subspecific Level

After years of studies in Aedes aegypti in Thailand it was revealed that there is a species complex at subspecific level comprising of the dark form or the type species and the pale form. The two forms were studies for susceptibility to dengue 2 virus by oral feeding. The dark form is more susceptible than the pale form

Biology of Dengue Vectors and Their Control in Thailand

The vectors of dengue, dengue haemorrhagic fever, and dengue shock syndrome are Aedes aegypti in the urban and rural areas and Aedes albopictus in the rural area. Aedes albolateralis a species member in Aedes niveus subgroup is highly susceptible to dengue 2 virus in laboratory. This species breeds in the forest in bamboo stump and tree hole and may be a source of sylvatic transmission. The anthropophilic, diurnal and domestic habit of Aedes aegypti in the increasing population of the world sustain aegypti population. In South East Asia aegypti is now invading albopictus the original species. Some evidences in biology morphotaxonomy, biochemistry indicate the plasticity of the species. The control strategy mainly for Aedes aegypti are (a) emergency control to interrupt transmission (b) larvicide (c) environmental management. Integrated control would be emphasized. Primary health care aims at extending health services to all the population and participation of each section of the community is essential and under the supervision of vector control professional, making use of the extensive research on vectors and their control

Suscetibilidade de duas formas cariotípicas de Anopheles aconitus (Diptera: Culicidae) a Plasmodium falciparum e P. vivax

Four laboratory-raised colonies of two karyotypic forms of Anopheles aconitus, i.e., Form B (Chiang Mai and Phet Buri strains) and C (Chiang Mai and Mae Hong Son strains), were experimentally infected with Plasmodium falciparum and P. vivax using an artificial membrane feeding technique and dissected eight and 12 days after feeding for oocyst and sporozoite rates, respectively. The results revealed that An. aconitus Form B and C were susceptible to P. falciparum and P. vivax, i.e., Form B (Chiang Mai and Phet Buri strains/P. falciparum and P. vivax) and Form C (Chiang Mai and Mae Hong Son strains/P. vivax). Comparative statistical analyses of the oocyst rates, average number of oocysts per infected midgut and sporozoite rates among all strains of An. aconitus Form B and C to the ingroup control vectors, An. minimus A and C, exhibited mostly no significant differences, confirming the high potential vector of the two Plasmodium species. The sporozoite-like crystals found in the median lobe of the salivary glands, which could be a misleading factor in the identification of true sporozoites in salivary glands were found in both An. aconitus Form B and C.Quatro colônias desenvolvidas em laboratório, de duas formas cariotípicas de Anopheles aconitus i.e. forma B (cepa Chiang Mai e Phet Buri) e C (Cepa Chiang Mai e Mae Hong Son), foram infectadas experimentalmente com Plasmodium falciparum e P. vivax usando técnica de alimentação com membrana artificial e dissecados oito e 12 dias após alimentação da média de oocistos e esporozoitos, respectivamente. Os resultados revelaram que An. aconitus formas B e C foram suscetíveis ao P. falciparum e P. vivax isto é, forma B (cepa Chiang Mai e Phet Buri/P. falciparum e P. vivax) e forma C (cepa Chiang Mai e Mae Hong Son/P. vivax). Análises estatísticas comparativas das taxas de oocistos, número médio de oocistos por intestino médio infectado e taxas de esporozoitos entre todas as cepas de An. aconitus formas B e C ao grupo interno de vetores controles, An. minimus A e C, não exibiram nenhuma diferença significante, confirmando o alto potencial vetor das duas espécies de Plamodium. Os cristais semelhantes a esporozoitos encontrados no lobo médio das glândulas salivares que poderiam ser um fator enganoso na identificação de esporozoitos verdadeiros nas glândulas salivares foram encontrados em ambos An. aconitus formas B e C

Present status of the insecticide susceptibility of Aedes mosquitoes in Thailand

デング熱の伝播を止めるのに現在使われている方法は、流行地域に殺虫剤を噴霧することである。そのような場合、媒介昆虫の殺虫剤感受性についての情報があれば、適切な殺虫剤を散布できるであろう。このことは対策プログラムの重要な要素でもある。そこで、WHO 感受性評価キットを使って、ネッタイシマカAedes aegypti とヒトスジシマカAe.albopictus の殺虫剤に対する感受性を調べた。2008 年から2010 年にかけて、バンコク、Phra Nakhon Si Ayutthaya(プラ・ナコーン・シー・アユタヤー)、Chantha Buri(チャンタブリー)、Prachin Buri(プラチンブリー)で採集し、実験室で飼育した蚊の成虫または幼虫に、WHO が推奨している識別判定が可能な投与量の殺虫剤に1 時間暴露させ、24時間後の死亡率を調べた。おおむね、ネッタイシマカはマラチオンを除く全ての殺虫剤に対して耐性あるいは抵抗性を示した。殺虫剤抵抗性の程度は、バンコク、プラ・ナコーン・シー・アユタヤー、プラチンブリー、チャンタブリーで、それぞれ高いレベルから低いレベルまで分布していた。バンコクのBang Khae(バンケー)区およびThung Khru(トゥンクル)区では、殺虫剤に対する抵抗性が毎年増してきていた。ピレスロイド抵抗性と関係があるノックダウン型抵抗性(kdr)型抵抗性が、ネッタイシマカで観察された。一方、プラチンブリー、バンコク、Phang-nga(パンガー)から採集したヒトスジシマカは、DDT に対して耐性を示した。しかし、ピレスロイドあるいはマラチオンに対して耐性/ 抵抗性を示したヒトスジシマカはいなかった。The current method for interrupting dengue fever transmission is spraying insecticide in the area affected by the epidemic. In such cases, information about the insecticide susceptibility of the vector would allow an appropriate insecticide to be applied. It is also a key factor for control programs. Therefore, the insecticide susceptibility of Aedes aegypti and Ae. albopictus were investigated using the WHO susceptibility test kit. Adult mosquitoes or larvae collected from Bangkok, Phra Nakhon Si Ayutthaya, Chanthaburi, and Prachin Buri from 2008-2010 and reared in a laboratorywere exposed to insecticide for 1 hour at discriminating diagnostic doses recommended by the WHO, and mortality was examined after 24 hour. In general, Ae. aegypti were tolerant or resistant to all insecticides except malathion. Their degrees of insecticide resistance ranged from high to low in Bangkok, Phra Nakhon Si Ayutthaya, Prachin Buri, and Chanthaburi, respectively. In the Bang Khae and Thung Khru districts of Bangkok, insecticide resistance increased each year. knock down resistance, which is related to pyrethroid resistance, was observed in Ae. aegypti. On the other hand, Ae. albopictus from Prachin Buri, Bangkok, and Phang-nga were able to tolerate DDT. However no Ae. albopictus that were tolerant/resistant to pyrethroid or malathion were found in this study

Effective suppression of Dengue fever virus in mosquito cell cultures using retroviral transduction of hammerhead ribozymes targeting the viral genome

Outbreaks of Dengue impose a heavy economic burden on developing countries in terms of vector control and human morbidity. Effective vaccines against all four serotypes of Dengue are in development, but population replacement with transgenic vectors unable to transmit the virus might ultimately prove to be an effective approach to disease suppression, or even eradication. A key element of the refractory transgenic vector approach is the development of transgenes that effectively prohibit viral transmission. In this report we test the effectiveness of several hammerhead ribozymes for suppressing DENV in lentivirus-transduced mosquito cells in an attempt to mimic the transgenic use of these effector molecules in mosquitoes. A lentivirus vector that expresses these ribozymes as a fusion RNA molecule using an Ae. aegypti tRNAval promoter and terminating with a 60A tail insures optimal expression, localization, and activity of the hammerhead ribozyme against the DENV genome. Among the 14 hammerhead ribozymes we designed to attack the DENV-2 NGC genome, several appear to be relatively effective in reducing virus production from transduced cells by as much as 2 logs. Among the sequences targeted are 10 that are conserved among all DENV serotype 2 strains. Our results confirm that hammerhead ribozymes can be effective in suppressing DENV in a transgenic approach, and provide an alternative or supplementary approach to proposed siRNA strategies for DENV suppression in transgenic mosquitoes

Comparative morphometry and morphology of Anopheles aconitus Form B and C eggs under scanning electron microscope

Comparative morphometric and morphological studies of eggs under scanning electron microscope (SEM) were undertaken in the three strains of two karyotypic forms of Anopheles aconitus, i.e., Form B (Chiang Mai and Phet Buri strains) and Form C (Chiang Mai and Mae Hong Son strains). Morphometric examination revealed the intraspecific variation with respect to the float width [36.77 +/- 2.30 microm (Form C: Chiang Mai strain) = 38.49 +/- 2.78 microm (Form B: Chiang Mai strain) = 39.06 +/- 2.37 microm (Form B: Phet Buri strain) > 32.40 +/- 3.52 microm (Form C: Mae Hong Son strain)] and number of posterior tubercles on deck [2.40 +/- 0.52 (Form B: Phet Buri strain) = 2.70 +/- 0.82 (Form B: Chiang Mai strain) <3.10 +/- 0.32 (Form C: Chiang Mai strain) = 3.20 +/- 0.42 (Form C: Mae Hong Son strain)], whereas the surface topography of eggs among the three strains of two karyotypic forms were morphologically similar

Susceptibility of two karyotypic forms of Anopheles aconitus (Diptera Culicidae) to Plasmodium falciparum and P. vivax

Four laboratory-raised colonies of two karyotypic forms of Anopheles aconitus, i.e., Form B (Chiang Mai and Phet Buri strains) and C (Chiang Mai and Mae Hong Son strains), were experimentally infected with Plasmodium falciparum and P. vivax using an artificial membrane feeding technique and dissected eight and 12 days after feeding for oocyst and sporozoite rates, respectively. The results revealed that An. aconitus Form B and C were susceptible to P. falciparum and P. vivax, i.e., Form B (Chiang Mai and Phet Buri strains/P. falciparum and P. vivax) and Form C (Chiang Mai and Mae Hong Son strains/P. vivax). Comparative statistical analyses of the oocyst rates, average number of oocysts per infected midgut and sporozoite rates among all strains of An. aconitus Form B and C to the ingroup control vectors, An. minimus A and C, exhibited mostly no significant differences, confirming the high potential vector of the two Plasmodium species. The sporozoite-like crystals found in the median lobe of the salivary glands, which could be a misleading factor in the identification of true sporozoites in salivary glands were found in both An. aconitus Form B and C