The effect of pesticides and aqueous extracts of Azadirachta indica (A. Juss) and Jatropha carcus L. on Bemisia tabaci (Gennadius) (Homoptera: Aleyrididae) and Helicoverpa armigera (Hübner)(Lepidoptera: Noctuidae) found on tomato plants in Côte d’Ivoire.

Objective: The objective was to evaluate the effects of foliar application of Jatropha and neem aqueous extracts compared to a conventional insecticide treatment on the number of whitefly Bemisia tabaci (Gennadius) and bollworm Helicoverpa armigera (Hübner), yield of tomatoes in plots and the potentials of using any of these aqueous extracts to control these insect pests.Methodology and results: the study was conducted in the region of Moronou (Bongouanou, Koffikro, CBC Kangandissou). The insecticides Décis 12 EC® and Cypercal 50 EC®, and neem and jatropha aqueous extract were used for tomato foliar treatment (neem and jatropha seeds 80 and 50g/L, neem leaves 67 g/L). The treatments of tomato plant plots with pesticides Decis® and Cypercal® showed similar yields of biopestcide made of neem and jatropha in Ahorosso (P=0.00), Bongouanou (P=0.07) and CBC Kangandissou (P=0.01) plots. All of these treatments reduced the number of Bemisia tabaci adults, reduced the number of Helicoverpa armigera larvae on tomato plants and increased number of fruits per plant, the fruit weight per plant and the yield.Conclusion and application of findings: Statistical analysis shows that aqueous extract of jatropha and neem seed 80 g/L and 50 g/L, and of neem leaves 67 g/L are as effective as pesticides Décis® and Cypercal® on Bemisia tabaci and Helicoverpa armigera. Consequently, these biopesticides increased the number of fruits per plant and yield. This result should enable use of aqueous extract of neem and jatropha seed and of neem leaves to protect tomato plants against Bemisia tabaci and  Helicoverpa armigera at farm.Keywords: Bemisia tabaci; Helicoverpa armigera; tomato crop; aqueous extract; biocontro

Hepatoprotective and antioxidant activities of Hibiscus sabdariffa petal extracts in Wistar rats

Background: Hibiscus sabdariffa is a medicinal plant rich in phytochemical compounds, which is the source of its biological properties. This study on the aqueous extract of H. sabdariffa (AEHS) was conducted to assess its hepatoprotective and antioxidant properties.Methods: It was carried out with 25 Wistar rats divided into five groups. Two groups were treated with a solution of NaCl 0.9%. One group was treated with silymarin at a dose of 25 mg/kg body weight (BW). Two other groups were treated with the AEHS at different doses (100 and 200 mg/kg BW). The treatments were carried out via oral route and at single dose for 7 days. After injection of 2,4-dinitrophenylhydrazine (DNPH), blood samples were collected for the carrying out of biochemical analyses of oxidative stress markers (thiobarbituric acid reactive substances, ferric reduction antioxidant parameter, and 2,2-diphenyl-1-picrylhydrazyl) and hepatotoxicity (albumin, total and direct bilirubin, alanine transaminase, aspartate aminotransferase, and lactate dehydrogenase).Results: Three major results were obtained. The hepatotoxicity of DNPH expressed by the rats of Group 1 was significantly different (p<0.05) from those of the other groups (control, 2-4) for both hepatotoxicity and oxidative stress markers. The hepatoprotective and antioxidant properties of the AEHS and confirmation of those of silymarin through the rats of Groups 2-4 were statistically identical (p<0.05) to the control group for markers of hepatotoxicity and oxidative stress.Conclusion: These results confirm and reinforce certain therapeutic virtues of H. sabdariffa

Dynamics of multiple insecticide resistance in the malaria vector Anopheles gambiae in a rice growing area in South-Western Burkina Faso

<p>Abstract</p> <p>Background</p> <p>Insecticide resistance of the main malaria vector, <it>Anopheles gambiae</it>, has been reported in south-western Burkina Faso, West Africa. Cross-resistance to DDT and pyrethroids was conferred by alterations at site of action in the sodium channel, the Leu-Phe <it>kdr </it>mutation; resistance to organophosphates and carbamates resulted from a single point mutation in the oxyanion hole of the acetylcholinesterase enzyme designed as <it>ace-1</it>^<it>R</it>.</p> <p>Methods</p> <p>An entomological survey was carried out during the rainy season of 2005 at Vallée du Kou, a rice growing area in south-western Burkina Faso. At the Vallée du Kou, both insecticide resistance mechanisms have been previously described in the M and S molecular forms of <it>An. gambiae</it>. This survey aimed i) to update the temporal dynamics and the circumsporozoite infection rate of the two molecular forms M and S of <it>An. gambiae </it>ii) to update the frequency of the Leu-Phe <it>kdr </it>mutation within these forms and finally iii) to investigate the occurrence of the <it>ace-1</it>^{<it>R </it>}mutation.</p> <p>Mosquitoes collected by indoor residual collection and by human landing catches were counted and morphologically identified. Species and molecular forms of <it>An. gambiae</it>, <it>ace-1</it>^{<it>R </it>}and Leu-Phe <it>kdr </it>mutations were determined using PCR techniques. The presence of the circumsporozoite protein of <it>Plasmodium falciparum </it>was determined using ELISA.</p> <p>Results</p> <p><it>Anopheles gambiae </it>populations were dominated by the M form. However the S form occurred in relative important proportion towards the end of the rainy season with a maximum peak in October at 51%. Sporozoite rates were similar in both forms. The frequency of the Leu-Phe <it>kdr </it>mutation in the S form reached a fixation level while it is still spreading in the M form. Furthermore, the <it>ace</it>-<it>1</it>^{<it>R </it>}mutation prevailed predominately in the S form and has just started spreading in the M form. The two mutations occurred concomitantly both in M and S populations.</p> <p>Conclusion</p> <p>These results showed that the Vallée du Kou, a rice growing area formerly occupied mainly by M susceptible populations, is progressively colonized by S resistant populations living in sympatry with the former. As a result, the distribution pattern of insecticide resistance mutations shows the occurrence of both resistance mechanisms concomitantly in the same populations. The impact of multiple resistance mechanisms in M and S populations of <it>An. gambiae </it>on vector control measures against malaria transmission, such as insecticide-treated nets (ITNs) and indoor residual spraying (IRS), in this area is discussed.</p

Western boundary circulation and coastal sea-level variability in Northern Hemisphere oceans

The northwest basins of the Atlantic and Pacific oceans are regions of intense western boundary currents (WBCs): the Gulf Stream and the Kuroshio. The variability of these poleward currents and their extensions in the open ocean is of major importance to the climate system. It is largely dominated by in-phase meridional shifts downstream of the points at which they separate from the coast. Tide gauges on the adjacent coastlines have measured the inshore sea level for many decades and provide a unique window on the past of the oceanic circulation. The relationship between coastal sea level and the variability of the western boundary currents has been previously studied in each basin separately, but comparison between the two basins is missing. Here we show for each basin that the inshore sea level upstream of the separation points is in sustained agreement with the meridional shifts of the western boundary current extension over the period studied, i.e. the past 7 (5) decades in the Atlantic (Pacific). Decomposition of the coastal sea level into principal components allows us to discriminate this variability in the upstream sea level from other sources of variability such as the influence of large meanders in the Pacific. Our result extends previous findings limited to the altimetry era and suggests that prediction of inshore sea-level changes could be improved by the inclusion of meridional shifts of the western boundary current extensions as predictors. Long-duration tide gauges, such as Key West, Fernandina Beach or Hosojima, could be used as proxies for the past meridional shifts of the western boundary current extensions

Testing of Aerosols for Lung Toxicity by In-Vitro Studies at the Air-Liquid Interface for up to 24 Hours

The state of the art of studying the health effects of aerosols in vitro is based on submerged exposure of collected particulate matter, suspended in culture medium. However, this method neglects the gas phase including their interactions with particles and cells. It may change the properties of the investigated particles and does not represent the actual process in the human lung. Exposure at the Air-Liquid Interface (ALI) avoids these disadvantages, but requires a comprehensive system to guarantee reproducible conditions. Therefore, KIT and VITROCELL Systems developed a fully automated ALI exposure station. The exposure station offers a complete measurement system for parallel exposure of up to 24 human lung cell cultures towards gases, nanoparticles and complex mixtures such as combustion aerosols. The aerosol flow, temperature, and humidity are adjusted to the conditions resembling the human lung. An internal negative control using humidified synthetic air is also implemented and the particle dose per time can be increased by electrostatic particle deposition. The particle mass per area deposited by diffusional as well as by electrostatic mechanism is monitored online using a quartz crystal microbalance. Additionally, a new tool to reproducibly expose sample grids for transmission electron microscopy was developed and applied. Image evaluation of TEM images delivers dose information with respect to the spatial distribution and the agglomeration state of the deposited particles. Applications of the ALI exposure station are environmental atmospheres and technical emission sources like marine diesel engines or wood combustion. Long-term stability of A549 lung cells was examined for exposure times up to 24 hours by exposing A549 cell cultures towards clean air as well as towards airborne titanium dioxide and copper oxide nanoparticles. Dose measurement data and biological responses as viability (AlamarBlue assay), cytotoxicity (LDH release), and release of cytokines during long-term exposure are reported

Development of vegetable farming: a cause of the emergence of insecticide resistance in populations of Anopheles gambiae in urban areas of Benin

<p>Abstract</p> <p>Background</p> <p>A fast development of urban agriculture has recently taken place in many areas in the Republic of Benin. This study aims to assess the rapid expansion of urban agriculture especially, its contribution to the emergence of insecticide resistance in populations of <it>Anopheles gambiae</it>.</p> <p>Methods</p> <p>The protocol was based on the collection of sociological data by interviewing vegetable farmers regarding various agricultural practices and the types of pesticides used. Bioassay tests were performed to assess the susceptibility of malaria vectors to various agricultural insecticides and biochemical analysis were done to characterize molecular status of population of <it>An. gambiae</it>.</p> <p>Results</p> <p>This research showed that:</p> <p>(1) The rapid development of urban agriculture is related to unemployment observed in cities, rural exodus and the search for a balanced diet by urban populations;</p> <p>(2) Urban agriculture increases the farmers' household income and their living standard;</p> <p>(3) At a molecular level, PCR revealed the presence of three sub-species of <it>An. gambiae </it>(<it>An. gambiae s.s., Anopheles melas and Anopheles arabiensis</it>) and two molecular forms (M and S). The <it>kdr </it>west mutation recorded in samples from the three sites and more specifically on the M forms seems to be one of the major resistance mechanisms found in <it>An. gambiae </it>from agricultural areas. Insecticide susceptibility tests conducted during this research revealed a clear pattern of resistance to permethrin (76% mortality rate at Parakou; 23.5% at Porto-Novo and 17% at Cotonou).</p> <p>Conclusion</p> <p>This study confirmed an increase activity of the vegetable farming in urban areas of Benin. This has led to the use of insecticide in an improper manner to control vegetable pests, thus exerting a huge selection pressure on mosquito larval population, which resulted to the emergence of insecticide resistance in malaria vectors.</p

Parasitological Indices of Malaria Transmission in Children under Fifteen Years in Two Ecoepidemiological Zones in Southwestern Burkina Faso

Twenty years after the latest publications performed on the parasitological indices of malaria transmission in northwest of the second city of Burkina Faso, it was important to update the epidemiological profile of malaria in children under the age of 15 years. The objective of this study was to determine and compare the parasitological parameters of malaria transmission by season, area, and age in the two zones (rice and savanna) in the northwest of Bobo-Dioulasso, Burkina Faso. Overall, the results showed that there was no significant difference in the parasitological indices of malaria transmission within children under fifteen years between the rice site and the savannah site and whatever the season (P>0.05). The profound environmental modifications that occurred in the rice zone would have led to changes in vector behavior and consequently to changes in the epidemiological profile of malaria, contrary to the results obtained since the last publications. An entomological study correlated with this study is therefore necessary for effective decision-making for the malaria control in both areas. Future research must now focus on the impact that these profound environmental modifications of rice area are having on malaria control in Burkina Faso

PCR-based methods for the detection of L1014 kdr mutation in Anopheles culicifacies sensu lato

<p>Abstract</p> <p>Background</p> <p><it>Anopheles culicifacies s.l</it>., a major malaria vector in India, has developed widespread resistance to DDT and is becoming resistant to pyrethroids–the only insecticide class recommended for the impregnation of bed nets. Knock-down resistance due to a point mutation in the voltage gated sodium channel at L1014 residue (<it>kdr</it>) is a common mechanism of resistance to DDT and pyrethroids. The selection of this resistance may pose a serious threat to the success of the pyrethroid-impregnated bed net programme. This study reports the presence of <it>kdr </it>mutation (L1014F) in a field population of <it>An. culicifacies s.l</it>. and three new PCR-based methods for <it>kdr </it>genotyping.</p> <p>Methods</p> <p>The IIS4-IIS5 linker to IIS6 segments of the para type voltage gated sodium channel gene of DDT and pyrethroid resistant <it>An. culicifacies s.l</it>. population from the Surat district of India was sequenced. This revealed the presence of an A-to-T substitution at position 1014 leading to a leucine-phenylalanine mutation (L1014F) in a few individuals. Three molecular methods viz. Allele Specific PCR (AS-PCR), an Amplification Refractory Mutation System (ARMS) and Primer Introduced Restriction Analysis-PCR (PIRA-PCR) were developed and tested for <it>kdr </it>genotyping. The specificity of the three assays was validated following DNA sequencing of the samples genotyped.</p> <p>Results</p> <p>The genotyping of this <it>An. culicifacies s.l</it>. population by the three PCR based assays provided consistent result and were in agreement with DNA sequencing result. A low frequency of the <it>kdr </it>allele mostly in heterozygous condition was observed in the resistant population. Frequencies of the different genotypes were in Hardy-Weinberg equilibrium.</p> <p>Conclusion</p> <p>The Leu-Phe mutation, which generates the <it>kdr </it>phenotype in many insects, was detected in a pyrethroid and DDT resistant <it>An. culicifacies s.l</it>. population. Three PCR-based methods were developed for <it>kdr </it>genotyping. All the three assays were specific. The ARMS method was refractory to non-specific amplification in non-stringent amplification conditions. The PIRA-PCR assay is able to detect both the codons for the phenylalanine mutation at <it>kdr </it>locus, i.e., TTT and TTC, in a single assay, although the latter codon was not found in the population genotyped.</p