Chemical Cues for Malaria Vectors Oviposition Site Selection:\ud Challenges and Opportunities

The attractiveness of oviposition site for malaria vector mosquitoes is dependent upon a number of physical and chemical factors. Many aspects of mosquito behavior, including host location and oviposition, are mediated by volatile semiochemicals. It is anticipated that selection of oviposition site by semio-chemicals in the form of attractants or stimulants can be used in oviposition traps to monitor or possibly in combination with insecticides to control gravid mosquito populations for mass trapping. So far, volatile compounds identified as oviposition attractants for mosquitoes include phenol, 4-methyl phenol, 4-ethyl phenol, indole, skatole, and p-cresol from hay infusions; 3-carene, terpinene, copaene, cedrene, and d-cadinene released by copepods; alcohol and terpenoids including p-cresol fromplants; ethyl acetate and hydrocarbon substances, probably released by filamentous algae; 3-methyl-1-butanol identified frombacteria. Research priorities should be directed at identifying more oviposition attractants to determine the properties of these semio-chemicals for possible use in designing control tools. This would aim at luring females to lethal traps or stimulants to increase their exposure to insecticide-impregnated substrates.\ud \u

Malaria vector control at crossroads: public health entomology and the drive to elimination

Vector control has been at the core of successful malaria control. However, a dearth of field-oriented vector biologists threatens to undermine global reductions in malaria burden. Skilled cadres are needed to manage insecticide resistance, to maintain coverage with current interventions, to develop new paradigms for tackling ‘residual' transmission, and to target interventions as transmission becomes increasingly heterogeneous. Recognising this human resource crisis, in September 2013, WHO Global Malaria Programme issued guidance for capacity building in entomology and vector control, including recommendations for countries and implementing partners. Ministries were urged to develop long-range strategic plans for building human resources for public health entomology and vector control (including skills in epidemiology, geographic information systems, operational research and programme management) and to set in place the requisite professional posts and career opportunities. Capacity building and national ownership in all partner projects and a clear exit strategy to sustain human and technical resources after project completion were emphasised. Implementing partners were urged to support global and regional efforts to enhance public health entomology capacity. While the challenges inherent in such capacity building are great, so too are the opportunities to establish the next generation of public health entomologists that will enable programmes to continue on the path to malaria eliminatio

Implementation of the global plan for insecticide resistance management in malaria vectors: progress, challenges and the way forward

In recent years, there has been an increase in resistance of malaria vectors to insecticides, particularly to pyrethroids which are widely used in insecticide-treated nets. The Global Plan for Insecticide Resistance Management in malaria vectors (GPIRM), released in May 2012, is a collective strategy for the malaria community to tackle this challenge. This review outlines progress made to date and the challenges experienced in the implementation of GPIRM, and outlines focus areas requiring urgent attention. Whilst there has been some advancement, uptake of GPIRM at the national level has generally been poor for various reasons, including limited availability of vector control tools with new mechanisms of action as well as critical financial, human and infrastructural resource deficiencies. There is an urgent need for a global response plan to address these deficits and ensure the correct and efficient use of available tools in order to maintain the effectiveness of current vector control efforts whilst novel vector control tools are under development. Emphasis must be placed on enhancing national capacities (such as human and infrastructural resources) to enable efficient monitoring and management of insecticide resistance, and to support availability and accessibility of appropriate new vector control products. Lack of action by the global community to address the threat of insecticide resistance is unacceptable and deprives affected communities of their basic right of universal access to effective malaria prevention. Aligning efforts and assigning the needed resources will ensure the optimal implementation of GPIRM with the ultimate goal of maintaining effective malaria vector control

Field evaluation of spatial repellency of metofluthrin-impregnated plastic strips against Anopheles gambiae complex in Bagamoyo, coastal Tanzania.

Metofluthrin is a newly synthesized pyrethroid possessing high knockdown and lethal activity against mosquitoes. Studies of metofluthrin-impregnated plastic strips have been performed with dengue vectors. This study reports the efficacy of the new prototypes of metofluthrin-impregnated plastic strips against malaria vectors, Anopheles gambiae complex, in the Kongo villages of Bagamoyo district in coastal Tanzania. The study, using 20 houses, half intervention, half control, was conducted for a 124-day period. Pyrethrum spray sheets and Centers for Disease Control and Prevention light traps were used to sample mosquito population indices. The mosquito density indices of the intervention houses were observed to be significantly lower than those of the control houses when pyrethrum spray sheet collection was used (F = 4.61, 1 df, P = 0.038; 98.7% reduction of total mosquito collection compared with that for the controls). These low indices were observed despite the large openings found in Bagamoyo houses, which were predicted to have a considerable negative effect on the spatial repellency of metofluthrin. Based on the present results, the pyrethrum spray sheet collection was the better of the 2 collection methods

Longitudinal evaluation of Ocimum and other plants effects on the feeding behavioral response of mosquitoes (Diptera: Culicidae) in the field in Tanzania

<p>Abstract</p> <p>Background</p> <p>The use of repellent materials from plants against nuisance insects is common with great potential to compliment existing malaria control programmes and this requires evaluation in the field. Ocimum plant species, <it>Ocimum suave </it>(Willd) and <it>O. kilimandscharicum </it>(Guerke) materials and their essential oils extracted by steam distillation were evaluated in the field and experimental huts for repellence, exophily and feeding inhibition effects against three mosquito species, <it>Anopheles arabiensis </it>(Patton), <it>An. gambiae </it>ss (Giles) and <it>Culex quinquefasciatus </it>(Say). The protective effect of essential oils from Ocimum plants were compared with N, N-diethly-3- methylbenzamide (DEET), a standard synthetic repellent. Also, the protective effect of fumigation by burning of repellent plants; <it>Ocimum suave, Ocimum kilimandscharicum</it>, <it>Azadirachta indica</it>, <it>Eucalyptus globules </it>and <it>Lantana camara </it>were tested in experimental huts and selected local houses.</p> <p>Results</p> <p>In the field, protection by Ocimum plants from mosquito bites was high and there was small variation among different mosquito species. Protection efficiency was 93.4%, 91.98% and 89.75% for <it>An. arabiensis </it>while for <it>Cx</it>. <it>quinquefaciatus </it>it was 91.30%, 88.65% and 90.50% for DEET, <it>Ocimum suave </it>and <it>O. kilimandscharicum </it>respectively. In the experimental hut, deterrence induced by burning of Ocimum and other plants ranged from 73.1.0% to 81.9% for <it>An. arabiensis </it>and 56.5% to 67.8% for <it>Cx. quinquefaciatus</it>, while feeding inhibition was 61.1% to 100% for <it>An. arabiensis </it>and 50% to 100% for <it>Cx. quinquefaciatus</it>. Evaluations under field conditions confirmed high protective efficacy, enhanced feeding inhibition and house entry inhibition (Deterrence).</p> <p>Conclusion</p> <p>This study shows the potential of <it>Ocimum suave and Ocimum kilimandscharicum </it>crude extracts and whole plants of <it>Ocimum suave, Ocimum kilimandscharicum</it>, <it>Azadirachta indica</it>, <it>Eucalyptus globules and Lantana camara </it>for use in protecting against human biting while the burning of plants reduces significantly the indoor resting mosquitoes.</p

Longitudinal evaluation of Ocimum and other plants effects on the feeding behavioral response of mosquitoes (Diptera: Culicidae) in the field in Tanzania

<p>Abstract</p> <p>Background</p> <p>The use of repellent materials from plants against nuisance insects is common with great potential to compliment existing malaria control programmes and this requires evaluation in the field. Ocimum plant species, <it>Ocimum suave </it>(Willd) and <it>O. kilimandscharicum </it>(Guerke) materials and their essential oils extracted by steam distillation were evaluated in the field and experimental huts for repellence, exophily and feeding inhibition effects against three mosquito species, <it>Anopheles arabiensis </it>(Patton), <it>An. gambiae </it>ss (Giles) and <it>Culex quinquefasciatus </it>(Say). The protective effect of essential oils from Ocimum plants were compared with N, N-diethly-3- methylbenzamide (DEET), a standard synthetic repellent. Also, the protective effect of fumigation by burning of repellent plants; <it>Ocimum suave, Ocimum kilimandscharicum</it>, <it>Azadirachta indica</it>, <it>Eucalyptus globules </it>and <it>Lantana camara </it>were tested in experimental huts and selected local houses.</p> <p>Results</p> <p>In the field, protection by Ocimum plants from mosquito bites was high and there was small variation among different mosquito species. Protection efficiency was 93.4%, 91.98% and 89.75% for <it>An. arabiensis </it>while for <it>Cx</it>. <it>quinquefaciatus </it>it was 91.30%, 88.65% and 90.50% for DEET, <it>Ocimum suave </it>and <it>O. kilimandscharicum </it>respectively. In the experimental hut, deterrence induced by burning of Ocimum and other plants ranged from 73.1.0% to 81.9% for <it>An. arabiensis </it>and 56.5% to 67.8% for <it>Cx. quinquefaciatus</it>, while feeding inhibition was 61.1% to 100% for <it>An. arabiensis </it>and 50% to 100% for <it>Cx. quinquefaciatus</it>. Evaluations under field conditions confirmed high protective efficacy, enhanced feeding inhibition and house entry inhibition (Deterrence).</p> <p>Conclusion</p> <p>This study shows the potential of <it>Ocimum suave and Ocimum kilimandscharicum </it>crude extracts and whole plants of <it>Ocimum suave, Ocimum kilimandscharicum</it>, <it>Azadirachta indica</it>, <it>Eucalyptus globules and Lantana camara </it>for use in protecting against human biting while the burning of plants reduces significantly the indoor resting mosquitoes.</p

Plasmodium falciparum Genetic Diversity in Western Kenya Highlands

The present study examined the genetic diversity and population structure of Plasmodium falciparum in western Kenya by analyzing the polymorphism of 12 microsatellite loci and two antigen loci. Malaria in highland areas is unstable and epidemic whereas malaria in lowland areas is endemic. Transmission intensity and malaria prevalence are substantially lower in the highlands than in the lowlands. Despite that the highland parasite populations exhibited reduced number of alleles, lower expected heterozygosity, and infection complexity in comparison to the surrounding lowland population, genetic diversity of the highland populations remained high in comparison to parasites from other meso-endemic regions. More than 70% of infections from western Kenya highland study sites were mixed genotype infections. Small but statistically significant genetic differentiation between highland and lowland populations was detected. These findings are discussed in the context of human travel and local transmission in the study area

Ethnobotanical study of some of mosquito repellent plants in north-eastern Tanzania

The use of plant repellents against nuisance biting insects is common and its potential for malaria vector control requires evaluation in areas with different level of malaria endemicity. The essential oils of Ocimum suave and Ocimum kilimandscharicum were evaluated against malaria vectors in north-eastern Tanzania. An ethnobotanical study was conducted at Moshi in Kilimanjaro region north-eastern Tanzania, through interviews, to investigate the range of species of plants used as insect repellents. Also, bioassays were used to evaluate the protective potential of selected plants extracts against mosquitoes. The plant species mostly used as repellent at night are: fresh or smoke of the leaves of O. suave and O. kilimandscharicum (Lamiaceae), Azadirachta indica (Meliaceae), Eucalyptus globules (Myrtaceae) and Lantana camara (Verbenaceae). The most popular repellents were O. kilimandscharicum (OK) and O. suave (OS) used by 67% out of 120 households interviewed. Bioassay of essential oils of the two Ocimum plants was compared with citronella and DEET to study the repellence and feeding inhibition of untreated and treated arms of volunteers. Using filter papers impregnated with Ocimum extracts, knockdown effects and mortality was investigated on malaria mosquito Anopheles arabiensis and Anopheles gambiae, including a nuisance mosquito, Culex quinquefasciatus. High biting protection (83% to 91%) and feeding inhibition (71.2% to 92.5%) was observed against three species of mosquitoes. Likewise the extracts of Ocimum plants induced KD90 of longer time in mosquitoes than citronella, a standard botanical repellent. Mortality induced by standard dosage of 30 mg/m2 on filter papers, scored after 24 hours was 47.3% for OK and 57% for OS, compared with 67.7% for citronella. The use of whole plants and their products as insect repellents is common among village communities of north-eastern Tanzania and the results indicate that the use of O. suave and O. kilimandscharicum as a repellent would be beneficial in reducing vector biting. The widespread use of this approach has a potential to complement other control measures

Mesure, notification et vérification de l’agriculture intelligente face au climat: changement de perspective, changement de possibilités ? Conclusions de l’auto-évaluation nationale des besoins, systèmes et opportunités

Depuis 2009, des milliards de dollars ont été investis dans des programmes d’AIC dans le but d’aider les petits exploitants à augmenter leur productivité tout en s’adaptant aux changements climatiques et en contribuant à les atténuer. Cependant, l’AIC a récemment dépassé les cercles de l’aide au développement et de la société civile, et les pays se sont mis à adopter des stratégies d’AIC dans le cadre de leurs politiques et stratégies de riposte aux changements climatiques et de développement agricole, notamment leurs Contributions déterminées au niveau national (CDN)