Small-scale Field Trials Research Articles

Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

Off-site lime stabilisation for treating faecal sludge was assessed by undertaking small-scale (35 L) and large-scale (600 L) field trials in Blantyre, Malawi. Hydrated lime was dosed to maintain pH 10, pH 10.5, pH 11, pH 11.5, and pH 12 depending on the buffer capacity of the faecal sludge in the four replica small-scale field trials. Significant reduction of E. coli to below the detection limit of 104 CFU/100 mL within 1 hour of treatment was reported for pH > 11. Based on the small-scale findings, large-scale field trials were conducted and greater than 3 log removal of E. coli was observed under pH 12 conditions. Therefore, based on the study, off-site lime stabilisation by dosing lime in the range of 10–35% w/w (dry solid basis), depending on the buffer capacity and solids content of the sludge to maintain pH > 11, can be used to sanitise faecal sludge during emergencies, as well as for existing on-site sanitation systems.

First evaluation of bendiocarb in experimental huts using different substrates in Madagascar.

BackgroundIndoor residual spraying with insecticide is recommended for malaria control in high-transmission settings. Determination of residual activity of insecticides is essential for the selection of appropriate indoor spraying policy. The present study was undertaken to evaluate the residual effect of bendiocarb, a carbamate insecticide used in Madagascar, on different indoor surfaces in order to elaborate future vector control interventions.MethodsThe residual activity of bendiocarb was evaluated in both experimental huts and houses. Tests in experimental huts on different substrates represented a small scale-field trials. The houses IRS performed in parallel of experimental huts IRS, was done to compare semi-field results and field results. Bioassays according to the World Health Organization (WHO) standard protocol were carried out on different substrates impregnated with bendiocarb using susceptible strains of Anopheles arabiensis and Aedes albopictus.ResultsBendiocarb induced significantly high mortality in treated huts against exposed mosquito (p < 0.005) compared to untreated huts. The mortality is up to the WHO threshold of 80 % during 5 months post-treatment. Using a multivariate analysis, Ae. albopictus mortality decreased significantly from the 3rd month post-treatment. However, An. arabiensis mortality decreased significantly from the 4th month after treatment. Comparing mosquito mortality results from the mud experimental huts and the mud houses showed no significant difference regarding the persistence of bendiocarb on wall.ConclusionsCurrent data suggest variable persistence of bendiocarb according to the type of wall surfaces, highlighting the importance of testing insecticide for IRS in local context before using them in large scale. Data from this study validate also the importance of using experimental huts as representative tool to evaluate the effectiveness of an insecticide.

Larvicidal efficacy of monoterpenes against the larvae of Anopheles gambiae

ObjectiveTo evaluate the larvicidal efficacy of eight volatile components of essential oils against 3rd instar larvae of Anopheles gambiae s.s. MethodsLarvicidal effects of each compound were evaluated in both laboratory and semi-field trials. Stock solution was prepared and serial dilutions were made in six concentrations for each compound. A total of 20 larvae were exposed to larvicides for each replicate and monitored at intervals of 12, 24, 48 and 72 h. Larvae monitoring was done on basis of dead and live larvae in all intervals. ResultsAll assayed compounds were larvicides and presented varying degrees of larval toxicity, with LC50 values ranging from 1.28 to 1938.92 mg/L depending on the treatment time (12, 24, 48 or 72 h). (−)-Perillyl alcohol presented the strongest larvicidal activity towards Anopheles gambiae larvae, with LC50 values of 73.60, 18.36, 1.72 and 1.28 mg/L after 12, 24, 48 and 72 h of exposure, respectively. The next strongest were (−)-isopulegol (LC50 = 135.10, 49.39, 34.39 and 20.22 mg/L) and (−)-carvone epoxide (LC50 = 168.86, 124.74, 80.84 and 23.46 mg/L). After 12, 24 and 48 h of treatment, hydroxydihydrocarvone was the least toxic compound, with LC50 values of 1938.92, 1172.18 and 401.03 mg/L, respectively. ConclusionsThe data obtained in this study suggest that all evaluated monoterpenes, especially (−)-perillyl alcohol, have remarkable larvicidal effects and may be considered as potential sources for the development of suitable natural larvicides for mosquito management programs. Further small-scale field trials should be conducted.

From Mundane to Smart

In addition to functional and technological features, the role of augmented objects should also be seen in terms of how effectively they fit into the everyday practices of users and how they enhance users' experiences. In this article, the authors introduce a low-tech, internet-of-things technology called CAM (Cooperative Artefact Memory) that is used as a collaborative tool in design studio environments. CAM works as an object memory technology and allows industrial and product designers to collaboratively store relevant information onto their physical design objects, such as sketches, collages, storyboards, and physical mock-ups in the form of messages, annotations and external web links. In the context of this study, CAM serves as an important probing device to understand designers' interaction and experiences with augmented design objects, in their natural environment. The authors carried out a small-scale field trial of CAM in an academic design studio, over three student design projects. In this article, they discuss the findings of their field trial and show how CAM was used by the participants, how it was integrated into the design process and how it was appropriated for different purposes. The authors also found that CAM supported coordination and awareness within the design teams, yet its serendipitous and asynchronous nature facilitated creative and playful interactions between team members. In general, the results show how CAM transformed mundane design objects into “smart” objects that made the creative and playful side of cooperative design visible.

Passive seismic imaging at depth using ambient noise fields recorded in a shallow buried sensor array

SUMMARY A small scale field trial of a buried receiver array is used to generate passive recordings during a period of minimal human activity at the site of the array. We carefully analyse the data to reveal a number of valuable insights. In particular, we find that shallow burial of the geophones improves noise levels significantly and in a strongly frequency dependent manner. By isolating ambient seismic noise, which is a significant noise contribution in the frequency range from 3Hz to 30Hz, we show it is possible to utilize this seismic energy for the purpose of deep imaging. We successfully use advanced techniques of seismic interferometry to produce images to reservoir depth (~2km) and below, which show very good agreement with 3D seismic images taken on site.

Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation.

In this research, three faecal sludge sanitizing methods—lactic acid fermentation, urea treatment and lime treatment—were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m3 of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment.

Widespread evidence for interspecific mating between Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in nature

Aedes aegypti and Aedes albopictus, two important vectors of the dengue and chikungunya viruses to humans, often come in contact in their invasive ranges. In these circumstances, a number of factors are thought to influence their population dynamics, including resource competition among the larval stages, prevailing environmental conditions and reproductive interference in the form of satyrization. As the distribution and abundance of Ae. aegypti and Ae. albopictus have profound epidemiological implications, understanding the competitive interactions that influence these patterns in nature is important.While evidence for resource competition and environmental factors had been gathered from the field, the evidence for reproductive interference, though strongly inferred through laboratory trials, remained sparse (one small-scale field trial). In this paper we demonstrate that low rates (1.12–3.73%) of interspecific mating occur in nature among populations of these species that have co-existed sympatrically from 3 to 150yrs. Finally this report contributes a new species-specific primer set for identifying the paternity of sperm extracted from field collected specimens.

Disruption of Darna pallivitta (Lepidoptera: Limacodidae) by Conventional and Mobile Pheromone Deployment.

Identification of the Darna pallivitta (Moore) pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOn-Bu) has made it possible to investigate communication disruption to control this lepidopteran pest. Conventional communication disruption trials showed marked decreases in the mean number of male moths captured in E7,9-10:COOnBu-treated fields compared with control fields. For traps baited with E7,9-10:COOnBu, percent disruptions were 94.4% and 92.1% for septa (1 g pheromone/ha, 1-wk trial duration) and spirals (6 g pheromone/ha, 8-wk trial duration) respectively. For traps baited with virgin female moths, percent disruption was 73.3% using septa disruptors (1 g pheromone/ha, 1-wk trial duration). Mobile communication disruption using Bactrocera cucurbitae (Coquillett) as carriers for E7,9-10:COOn-Bu was evaluated in the following three areas: fly survivorship, attraction of male moths to treated flies, and moth disruption in a small-scale field trial. Topical application of E7,9-10:COOnBu showed no significant decrease in survivorship at 50 and 80 µg/fly. However, decreased survivorship was observed at 100 µg/fly and linear regression showed E7,9-10:COOnBu dose was significantly correlated with B. cucurbitae survivorship. Traps containing honey–pheromone-fed flies attracted and caught D. pallivitta over a 1-wk period, demonstrating the attractiveness of the carrier. Releasing E7,9-10:COOnBu-fed B. cucurbitae (∼2 g pheromone/ha, 1-wk trial duration) resulted in significantly reduced trap catches in treatment fields compared with control fields on the first 2 d of the field trial. Percent disruptions were 84.7% (day 1) and 56.0% (day 2). These results suggest that both conventional communication disruption and mobile communication disruption have potential to control D. pallivitta.

Categorization of field trials with GM plants in the Netherlands: applicable to field trials with GM forest trees?

In the Netherlands, criteria have been set for field trials with genetically modified (GM) plants. These criteria are based on the step-by-step principle as described in European Directive 2001/18/EC. Three categories of field trials are defined. The first category concerns small-scale field trials with GM plants that are not well characterised on the molecular and phenotypic level. Confinement measures are applied in order to limit potential adverse effects to the field location. The second category consists of small-scale field experiments with GM plants that are better characterized. Confinement measures are no longer necessary since sufficient information is available to assess potential adverse effects on human health and the environment for these trials. The third category consists of large-scale field trials with fully characterised GM plants and without the need of confinement measures. For each category, a new permit is required. This system has been used for several crops, including apple and poplar trees and may also be applicable for trials with GM forest trees.

室内および小規模フィールド実験による石炭地下ガス化 (UCG) のエネルギー回収率評価

Cavity growth occurring with crack extension and coal consumption during UCG processes directly influences the gasifi cation effi ciency and the estimated subsidence and gas leakage to the surface. This report presents an evaluation of the gas energy recovery, coal consumption, and gasification cavity estimation using a proposed stoichiometric method to analyze the coal gasifi cation reaction process. We defi ned the evaluation parameters of rate of energy recovery and investigated the effects of different parameters using UCG trials conducted with coal blocks and coal seams, adopting different Linking-hole methods and operational parameters. Analyses of results obtained from laboratory experiments and small-scale field trials using V-shaped and L-shaped linking holes, and Coaxial-hole UCG models show that the gasification of Linking-hole models yielded average calorific values of product gas as high as 10.26, 11.11 MJ/m 3 (lab.), and 14.39 MJ/m 3 (field. ). In contrast, the Coaxial-hole models under experimental conditions yielded average calorifi c values of product gas as: 7.38, 4.70 MJ/m 3 (lab.) and 6.66 MJ/m 3 (field. ). The cavity volume obtained with Coaxial models was about half of the volume obtained from Linking-hole models. Results obtained for these UCG systems show that the feed gas and linking-hole types can infl uence coal consumption and product gas energy. Fissure ratios were also investigated. Results confi rmed major factors underpinning gasifi cation effi ciency. Linking-hole types strongly infl uenced the development of the oxidization surface and fracture cracks for subsequent combustion in the gasification zone. Estimated gas energy recovery results support experimental observations within an acceptable error range of about 10%. Moreover, this stoichiometric approach is simple and useful for evaluating the underground cavity during UCG. Based on these results, we proposed a definition of the energy recovery rate, combined with the obtained volumes of gasification ca vities that provide a definition of ener gy recovery and UCG effects.

A small-scale field trial of pyriproxyfen-impregnated bed nets against pyrethroid-resistant Anopheles gambiae s.s. in western Kenya.

Pyrethroid resistance is becoming a major problem for vector control programs, because at present, there are few suitable chemical substitutes for pyrethroids, as when used on bed nets the insecticide must have low mammalian toxicity as well as high activity to mosquitoes. Pyriproxyfen (PPF) is one of the most active chemicals among the juvenile hormone mimic (JHM) group. Sterilizing mosquitoes by using PPF could be a potential control measure for pyrethroid-resistant malaria vectors. We investigated the sterilizing effects of two types of PPF-impregnated bed nets – a 1% PPF-impregnated net and a 1% PPF +2% permethrin-impregnated net (Olyset Duo) – to pyrethroid-resistant wild population of Anopheles gambiae s.s. in western Kenya. High mortality of blood-fed mosquitos was observed 3 days post-collection, in the houses where PPF-impregnated nets were used, indicating the effect of PPF on the longevity of mosquitos that came in contact with the net. Reduction in the number of ovipositing females, number of eggs, and number of progeny per female were also observed in the houses in which both Olyset Duo and PPF-impregnated nets were used. This is the first field study showing the high sterilizing efficacy of PPF against wild pyrethroid-resistant An. gambiae s.s. population. In addition, we recognized the necessity of combined use of permethrin with PPF, in order to reduce the risk of mosquito bites and provide a level of personal protection. Further studies on wild pyrethroid-resistant mosquito populations such as An. arabiensis and An. funestus s.s. would provide more information on the practical use of the PPF-impregnated bed nets.

Preference of Aphids (Hemiptera: Aphididae) for Lucerne, Maize, Soybean and Wheat and their Potential as Prospective Border Crops forPotato virus yManagement in seed Potatoes

Aphid landing rates, species composition and abundance on lucerne (Medicago sativa), maize (Zea mays), soybean (Glycine max), wheat (Triticum aestivum) and potato (Solanum tuberosum) were determined in a small-scale field trial to identify potential crops as prospective border plants for seed potatoes to reduce the spread of Potato virus (PVY) in South Africa. Aphids were sampled using green bucket traps to estimate aphid landing rates, whereas leaf counts and sweep-netting were used to identify colonizing species. Of the 34 species or species groups collected with green bucket traps, 18 were previously known vectors of PVY. The most abundant vector species or species groups were Acyrthosiphon pisum, Macrosiphum euphorbiae, Metopolophium dirhodum, Myzus persicae, Rhopalosiphum padi and Sitobion spp. The only other species that occurred in high numbers, but whose vector status is unknown, were Acyrthosiphon kondoi and Tetraneura fusiformis. Landing patterns suggest that A. kondoi, A. pisum and M. dirhodum may be able to discriminate between plant species and select their preferred host plant, if available within a habitat patch, in the pre-alighting phase, whereas other species such as R. padi seemed less selective. Results on aphid landing together with colonization of the crops evaluated suggest that maize and wheat show the highest potential as possible crop border plants in regions where aphids colonizing Poaceae, and lucerne in regions where aphids colonizing Fabaceae are abundant. Soybean appears to be less suitable because cultivars with a high trichome density, which reduces colonization by aphids, are preferentially planted in South Africa.

Assessment of an immunomarking technique for the study of dispersal of Culicoides biting midges

Capture–mark–recapture techniques are used to determine the dispersal and survival of arthropods, including vector groups such as Culicoides. An assumption of these studies is that capture and the subsequent marking process does not impact of the survival and behaviour of the marked individual. The small size of Culicoides means that a significant mortality and disruption of normal behaviour such as host-location can be caused by the process of collection. Here we evaluate a technique, novel to the study of dispersal in vectors, to mark Culicoides directly and indirectly without prior capture. The acquisition and subsequent detection of marker protein by Culicoides exposed to a treated substrate was investigated in the laboratory. The technique was then assessed in a small-scale field trial where a defined section of resting habitat was sprayed with an egg white solution and Culicoides caught within the vicinity were tested for the presence of egg protein. It was found that up to 100% of Culicoides acquired the protein marker in the laboratory with no apparent impact on survival. In the field, pools of Culicoides obsoletus collected next to the treated area were found to be positive for the protein, suggesting that the technique could be used in larger-scale studies. The definition of a behaviourally non-invasive technique for marking Culicoides will greatly increase our understanding of the natural dispersal behaviour of Culicoides and other vectors.

Laboratory and experimental hut evaluation of a long-lasting insecticide treated blanket for protection against mosquitoes

BackgroundLong-lasting insecticide treated blankets (LLIBs) may provide additional protection against malaria where use of long lasting insecticidal nets (LLIN) is low or impractical such as in disaster or emergency situations.MethodsInitial efficacy testing of a new candidate LLIB was carried out at LSHTM and KCMUCo, before and after washing, in cone and ball bioassays and arm-in-cage tests against pyrethroid susceptible Anopheles gambiae. A small scale field trial was conducted using veranda-trap experimental huts in northern Tanzania against wild An. arabiensis and Culex quinquefasciatus mosquitoes. Treatments included unwashed and 5 times washed permethrin treated LLIB and blankets hand-treated with permethrin (ITB), untreated blankets, and a holed unwashed Olyset net.ResultsCone test mortality was 75% for LLIB when unwashed, but decreased to 32% after 5 washes and <10% after 10 washes. In arm-in-cage tests protection against biting was 100% for LLIBs regardless of the number of washes while reduction in landings was 79% when unwashed, 75% after 5 washes, but declined to 41% after 10 and 33% after 20 washes. In ball bioassays using pyrethroid resistant An. arabiensis, mortality was low in all treatments (<35%) and there was no significant difference in mortality between Olyset net, LLIB or ITB (p > 0.05). Percentage mortality of An. arabiensis in huts with LLIB unwashed (26%) was not statistically different to Olyset net (31%, p = 0.5). The 5 times washed LLIB reduced blood-feeding by 49% which was equivalent to Olyset net (p > 0.086). There was no significant difference in percentage blood-feeding between LLIB and ITB unwashed or 5 times washed (p = 0.147 and p = 0.346 respectively). The 5 times washed LLIB reduced blood-feeding of Culex quinquefasciatus by 40%, although the Olyset provided the greatest protection with 85% inhibition. ELISA analysis of a sub-sample of blood fed mosquitoes showed that not all had fed on humans in the huts, therefore blood-feeding inhibition may have been underestimated.ConclusionsThis trial demonstrated the potential of LLIBs to provide substantial personal protection even against pyrethroid resistant mosquitoes. LLIBs may prove particularly useful where LLINs are unsuitable or net usage is low.

Decision Methodology for Temperature Control of Pavements

About 2.5 million miles of paved roads, which would cover an area about the size of the state of Georgia, exist in the United States. Pavements accumulate and dissipate solar energy in daily cycles. The increased heat in the pavement has many detrimental effects, including the accelerated degradation of the pavement, which results in increased costs to departments of transportation, and urban warming, which results in increased costs for cooling nearby inhabited structures and possibly contributes to microclimate change. Techniques such as heat exchangers that capture heat energy and transfer it to other forms of energy can reduce the extreme temperatures in pavements. Laboratory and some small-scale field trials of these systems have been conducted; however, the technology has not received wide implementation to date. Challenges to such implementation include limited documentation on the effectiveness of pavement cooling, a lack of accepted standard designs, a lack of evidence of long-term performance, the need for more efficient heat exchangers, and the cost of the system. Technological developments are rapidly overcoming the challenges, and the potential benefits of energy recovery are significant and include extended pavement life, reduced energy consumption in areas surrounding the pavement, improved air quality, the production of energy that could be used for other applications, and reduced microclimate impacts. This paper presents a decision methodology that would help designers and stakeholders evaluate, in terms of performance and cost measures, alternatives for systems to control pavement temperatures.

Implementing disability evaluation and welfare services based on the framework of the international classification of functioning, disability and health: experiences in Taiwan

BackgroundBefore 2007, the disability evaluation was based on the medical model in Taiwan. According to the People with Disabilities Rights Protection Act, from 2012 the assessment of a person’s eligibility for disability benefits has to be determined based on the International Classification of Functioning, Disability, and Health (ICF) framework nationwide. The purposes of this study were to: 1) design the evaluation tools for disability eligibility system based on the ICF/ICF-Children and Youth; 2) compare the differences of grades of disability between the old and new evaluation systems; 3) analyse the outcome of the new disability evaluation system.MethodsTo develop evaluation tools and procedure for disability determination, we formed an implementation taskforce, including 199 professional experts, and conducted a small-scale field trial to examine the feasibility of evaluation tools in Phase I. To refine the evaluation tools and process and to compare the difference of the grades of disability between new and old systems, 7,329 persons with disabilities were randomly recruited in a national population-based study in Phase II. To implement the new system smoothly and understand the impact of the new system, the collaboration mechanism was established and data of 168,052 persons who applied for the disability benefits was extracted from the information system and analysed in Phase III.ResultsThe measures of the 43 categories for body function/structure components, the Functioning Scale of Disability Evaluation System for activities/participation components, and the needs assessment have been developed and used in the field after several revisions. In Phase II, there was 49.7% agreement of disability grades between the old and new systems. In Phase III, 110,667 persons with a disability received their welfare services through the new system. Among them, 77% received basic social welfare support, 89% financial support, 24% allowance for assistive technology, 7% caregiver support, 8% nursing care and rehabilitation services at home, and 47% were issued parking permits for persons with disability.ConclusionThis study demonstrated that disability evaluation system based on the ICF could provide a common language between disability assessment, needs assessment and welfare services. However, the proposed assessment protocol and tools require additional testing and validation.

Evaluation of the potential for interspecific hybridization between Camelina sativa and related wild Brassicaceae in anticipation of field trials of GM camelina

Camelina (Camelina sativa (L.) Crantz) is a re-emergent oilseed crop that is also becoming important as a model for applied projects based on studies in Arabidopsis thaliana, since the two species are closely related members of the tribe Camelineae of the Brassicaeae. Since camelina can be transformed genetically by floral dip, genetically modified (GM) camelina is being created in many laboratories, and small-scale field trials are already being conducted in the US and Canada. Although camelina does not cross-fertilize Brassica crop species, such as oilseed rape, nothing was known about its ability to cross with other members of the tribe Camelineae, which in addition to arabidopsis includes the widespread weed, shepherd's purse (Capsella bursa-pastoris). We have tested the ability of camelina to cross with arabidopsis and C. bursa-pastoris, as well as with the more distantly related Cardamine hirsuta, tribe cardamineae. No seeds were produced in crosses with arabidopsis, and a few seeds were obtained in crosses with C. hirsuta, but the embryos aborted at an early stage of development. A few seeds were also obtained in crosses with C. bursa-pastoris, which germinated to produce plants of a phenotype intermediate to that of the parents, but the hybrids were both male and female sterile. Therefore, the likelihood of pollen-mediated gene flow from camelina to these related species is low.

Identifying critical incidents in naturalistic driving data: experiences from a promoting real life observation for gaining understanding of road user behaviour in Europe small‐scale field trial

The methodology of naturalistic driving observation aspires to observe the driver and his environment while driving in natural driving settings. It is of great importance in research on road safety as this method of observing road users eliminates the disadvantages of traditional methods like simulator studies or interviews. However, it produces vast such amounts of data and challenges data reduction and data analysis. Therefore automatic methods for filtering critical incidents based on thresholds for numerical data are often applied to select the data to be analysed. This study reports a small-scale field trial in Valencia, Spain, which was conducted within the promoting real life observation for gaining understanding of road user behaviour in Europe project. The analysis of the numerical data using thresholds resulted in a great number of false alarms and did not identify safety-critical sequences. In contrast, video analysis revealed a number of critical events that had not been previously detected using the numerical parameters. The study conveyed the importance of continuous video recording in these kinds of studies and showed that the methodology of data reduction for naturalistic driving studies requires further development in order to be able to capture all the relevant incidents automatically.

Bioefficacy of botanical insecticides against the dengue and chikungunya vector Aedes aegypti (L.) (Diptera: Culicidae)

ObjectiveTo determine the bioefficacy of plant extracts viz., whole plants of Sphaeranthus indicus (Asteraceae) and Citrullus colocynthis (Cucurbitaceae), leaves of Abutilon indicum (Malvaceae), Cleistanthus collinus (Euphorbiaceae), Leucas aspera (Lamiaceae) and Murraya koenigii (Rutaceae), and aerial parts of Hyptis suaveolens (Lamiaceae) against the dengue and chikungunya vector Aedes aegypti. MethodsThe larvicidal activity was determined against the early third instar larvae at concentrations of 250, 500, 750 and 1000 ppm. Larval mortality was assessed after 24 h. ResultsThe ethyl acetate extract of Sphaeranthus indicus (201.11ppm) and hexane extract of Abutilon indicum (261.31ppm) was found to be effective. ConclusionsFurther in-depth investigations on the crude extract/phytotoxic compounds of Sphaeranthus indicus are needed to elucidate the larvicidal activity against a wide range of all stages of mosquito species and also the active ingredients of the extract responsible for larvicidal activity in Aedes aegypti should be identified, and small scale field trials are needed for usage of this plant as a mosquitocidal agent.

Dengue Control: The Challenge Ahead

Dengue Control: The Challenge Ahead