Days In Laboratory Conditions Research Articles

Larvicidal properties of terpenoid-based nanoemulsions against the dengue vector Aedes aegypti L. and their potential toxicity against non-target organism.

The development of insecticide resistance in mosquitoes of public health importance has encouraged extensive research into innovative vector control methods. Terpenes are the largest among Plants Secondary Metabolites and have been increasingly studied for their potential as insecticidal control agents. Although promising, terpenes are insoluble in water, and they show low residual life which limits their application for vector control. In this study, we developed and evaluated the performances of terpenoid-based nanoemulsions (TNEs) containing myrcene and p-cymene against the dengue vector Aedes aegypti and investigated their potential toxicity against non-target organisms. Our results showed that myrcene and p-cymene showed moderate larvicidal activity against mosquito larvae compared to temephos an organophosphate widely used for mosquito control. However, we showed similar efficacy of TNEs against both susceptible and highly insecticide-resistant mosquitoes from French Guyana, hence suggesting an absence of cross-resistance with conventional insecticides. We also showed that TNEs remained effective for up to 45 days in laboratory conditions. The exposure of zebrafish to TNEs triggered behavioral changes in the fish at high doses but they did not alter the normal functioning of zebrafish organs, suggesting a good tolerability of non-target organisms to these molecules. Overall, this study provides new insights into the insecticidal properties and toxicity of terpenes and terpenoid-based formulations and confirms that TNE may offer interesting prospects for mosquito control as part of integrated vector management.

Farklı Molaritelere Sahip KOH Çözeltisi Kullanılarak Üretilen Cüruf Esaslı Geopolimer Harçlarda Kür Sıcaklığı Etkisinin İncelenmesi

Bu çalışmada, farklı kür sıcaklıklarına ve farklı potasyum hidroksit (KOH) oranlarına sahip yüksek fırın cüruflu (YFC) geopolimer harçların fiziksel ve mekanik özellikleri incelenmiştir. Geopolimer harçların karışımında; YFC, su ve agrega miktarı sabit tutulurken KOH’in molaritesi 5, 10, 15, 20 M olarak belirlenmiştir. Hazırlanan harçlar 40x40x160 mm ebatlarında prizma kalıplara yerleştirilmiş ve 50, 75 ve 100 °C sıcaklıklarda 24 saat küre tabi tutulmuşlardır. Elde edilen numuneler; 1, 7 ve 28 gün laboratuvar koşullarında bekletildikten sonra dayanım değerleri belirlenmiştir. Ayrıca 28 günlük harçların birim ağırlık, su emme, boşluk oranı ve ultrases geçiş hızı gibi fiziksel özellikleri belirlenmiştir.

The Evaluation of Different Feeds on Brine Shrimp, Artemia parthenogenetica Culture

In this study, Artemia parthenogenetica was fed with either Spirulina (S), yeast (Y), rice bran (R), oat (O) or their combinations in 10 experimental groups in triplicate for 20 days in laboratory conditions and growth, biomass, feed conversion rate (FCR), specific growth rate (SGR), survival rate, crude protein, crude lipid contents were determined. The highest average body length obtained at the end of the experiment was 2.805±0.003 mm in treatments (S) and (SYR), and the highest average individual dry weight was 23.057 µg in treatment (S). The mean biomass changed between 167.2±0.003 mg and 115.7±0.012 mg. The highest biomass value was 20.9 g/m3 in treatment (S), followed by 20.5 g/m3 in treatment (SYR). The highest FCR was found to be similar in (S) and (Y) with 1.14±0.02. SGR was 1.01±0.001 in all experimental groups. The highest survival rate was in treatment (S), and overall it ranged between 78.22±1.78 - 90.64±0.06%. The highest crude protein contents of Artemia were found in (SR) and (S) and the highest lipid content was found in treatment (O). As a result, it is thought that combinations of by-products such as rice bran and yeast together with microalgae will be economical in the cultivation of Artemia parthenogenetica.

Vermicomposting of Lavender Waste: A Biological Laboratory Investigation

In the present work, lavender waste, a residue of the essential oil extract industry, was used to feed Eisenia andrei with mature horse manure at ratios of 0:100, 25:75, 50:50, 75:25 and 100:0 on dry weight basis. Vermicomposting was carried out for 70 days in laboratory conditions. Biological parameters such as population build-up, total biomass, mortality and cocoon production were observed and measured. Increasing concentrations of waste affected positively the growth and reproduction of worms in a significant way. The 100% lavender waste combination showed the best cocoon production and even tripled their biomass in the first week. A seed germination test was also made, where no evidence of toxicity was found. The germination index range was, in general terms, above 100. The results indicated that the earthworm E. andrei was able to transform lavender waste into compost and thus play a major role in industrial waste management and apply circular economy.

Comparing the histological effect of Thymol from multiple sources with blood lipids profile and liver enzymes in Albino Mice

The therapeutic value of the phenolic component and pure thymol was well known; this study comprised the extraction of crude phenol from two plants (Thymus vulgaris and Artemisia annua) which contain thymol with pure thymol and evaluate their effect on hematological and histological by using three different concentrations of each plant extract and pure thymol to tested them on lab mice. All the mice were allowed free access to water and feed for 21 days in laboratory conditions; orally, pure water was administered to the control mice (group I), while groups II, III, and IV were given orally with T. vulgaris, A. annua, combination of last two crude phenol plant extract 50:50 and pure thymol respectively. The levels of CHO, TRI, and HDL were significantly reduced in A. annua and T. vulgaris crude phenolic extract at 20 mg/ml as compared to the control treatment, while pure Thymol at 10 mg/ml gave the best result in reducing the levels of CHO, TRI, and HDL. In comparison to the control group, serum levels of liver enzymes in groups treated with in A. annua, T. vulgaris extract, and pure Thymol were substantially reduced in concentration: 20, 10 and 30 mg/ml, respectively.

Morphology, biology, and damage behaviors of nutsedge borer (Bactra venosana Zeller) in Tra Vinh Province, Vietnam

Abstract. Nguyen HU, Phan QN, Dang HT, Son TTN, Nguyen HN, Nguyen THT. 2021. Morphology, biology, and damage behaviors of nutsedge borer (Bactra venosana Zeller) in Tra Vinh Province, Vietnam. Biodiversitas 23: 733-741. Nutsedge borer, Bactra venosana Zeller (Lepidoptera: Tortricidae), is a common pest of sedge in Tra Vinh Province. To control this species, its morphology, biology, and behaviors were investigated in Tra Vinh Province. The study was conducted with the aim of determining the information related to the Bactra venosana, as a basis for developing a strategy to manage this species by means of safety solutions. The study was carried out by surveying the behavior of nutsedge borer in sedge fields and determining their morphological and biological characteristics under laboratory conditions. The results showed that the eggs were 1.06 ± 0.17 mm (in length), 0.84 ± 0.16 (in width), oval, and white after turning pale yellow. Larvae progressed through 5 instars with body length and width of 1.20 ± 0.18 mm to 11.3 ± 1.23 mm and from 0.25 ± 0.05 to 1.05 ± 0.25 mm, respectively. Newly hatched larvae were dark yellow, and pupae were pale green. The male pupa was 7.75 ± 0.68 mm long, while the female was 8.46 ± 0.93 mm long, light green, and dark brown about to mature. The male adult of B. venosana was usually gray-brown and 7.70 ± 0.60 mm in body length, whereas the female adult was silver-gray, 8.41 ± 0.86 mm. The life cycle passed 35.9 ± 2.55 days in laboratory conditions. Under field conditions, eggs were laid scattered on the surface of the host plants. Larvae bored inside the stems of sedge. Newly damaged sedge plants had no symptoms at first whose bodies got soft, turned from light green to pale yellow, and gradually wilted and died.

Oil Spill Detection Using Fluorometric Sensors: Laboratory Validation and Implementation to a FerryBox and a Moored SmartBuoy

A large part of oil spills happen near busy marine fairways. Presently, oil spill detection and monitoring are mostly done with satellite remote sensing algorithms, or with remote sensors or visual surveillance from aerial vehicles or ships. These techniques have their drawbacks and limitations. We evaluated the feasibility of using fluorometric sensors in flow-through systems for real-time detection of oil spills. The sensors were capable of detecting diesel oil for at least 20 days in laboratory conditions, but the presence of CDOM, turbidity and algae-derived substances substantially affected the detection capabilities. Algae extract was observed to have the strongest effect on the fluorescence signal, enhancing the signal in all combinations of sensors and solutions. The sensors were then integrated to a FerryBox system and a moored SmartBuoy. The field tests support the results of the laboratory experiments, namely that the primary source of the measured variation was the presence of interference compounds. The 2 month experiments data did not reveal peaks indicative of oil spills. Both autonomous systems worked well, providing real-time data. The main uncertainty is how the sensors' calibration and specificity to oil, and the measurement depth, affects oil detection. We recommend exploring mathematical approaches and more advanced sensors to correct for natural interferences.

Determination of Pleurotus abieticola ligninolytic activity on Norway spruce wood

Abstract The effect of Phlebiopsis gigantea treatment in control of Heterobasidion parviporum in Norway spruce is less effective than that in control of Heterobasidion annosum in pine. It is necessary to apply other fungi, for example, Pleurotus abieticola in Norway spruce stands. Thus, it is necessary to assess the activity of major ligninolytic enzymes, that is, laccase, lignin peroxidase (LiP), manganese peroxidase (MnP) and versatile peroxidase (VP) produced by P. abieticola, which may be effective in the fast degradation of Norway spruce wood. Three strains of P. abieticola (Pa1-3) were grown on pieces of Norway spruce sapwood and heartwood for 50 days in laboratory conditions. Enzymatic activity was determined using spectrophotometry. Pleurotus abieticola produced laccase, LiP, MnP and VP. The activity of laccase was low, ranging 0–3.696 and 0–0.806 mU/μg of protein in sapwood and heartwood, respectively. The highest activity in Pa1 = 3.696 mU/μg of protein in sapwood and in Pa3 = 0.806 mU/μg of protein in heartwood was observed after 30 and 50 days of incubation, respectively. The activity of LiP was also low, ranging 0–0.188 and 0–0.271 mU/μg of protein in sapwood and heartwood, respectively. The highest activity in Pa1 = 0.271 mU/μg of protein in sapwood and in Pa2 = 0.188 mU/μg of protein in heartwood was observed after 40 and 20 days of incubation, respectively. The activity of MnP ranged 0–17.618 and 0–12.203 mU/μg of protein in sapwood and heartwood, respectively. This enzymatic activity peaked at the 50th day of culture on sapwood for the Pa3 strain (17.618 mU/μg of protein) and at the 20th day of culture on heartwood for the Pa1 strain (12.203 mU/μg of protein). The activity of VP with manganese-oxidising properties was found to be high in all strains of P. abieticola, ranging 0–39.19 and 0–59.153 mU/μg of protein in sapwood and heartwood, respectively, whereas the activity of VP with guaiacol-oxidising properties was very low for all P. abieticola strains, ranging 0–0.248 and 0–0.225 mU/μg of protein in sapwood and heartwood, respectively. The values of released hydroxyphenols in P. abieticola strains ranged 24.915–139.766 and 25.19–84.562 µg of protocatechuic acid/ml in sapwood and heartwood, respectively. The values of released methoxyphenols for the evaluated strains of P. abieticola ranged 7.225–23.789 and 1.953–20.651 µg of vanillic acid/ml in sapwood and heartwood, respectively. Further studies with a higher number of strains of this species as well as an optimisation of conditions for the measurement of ligninolytic activity are needed.

Nitrogen Mineralization and Nitrification in Two Soils with Different pH Levels

ABSTRACTSoil pH is one of the properties that mostly influences nitrification rates, and can be used as a tool for controlling this process, seen that depending on its extent it may lead to nitrogen (N) losses and subsequent contaminations. The aims of this study were to evaluate mineralization and nitrification of two soils at different pH levels. The experimental design was factorial with two factors and three replicates, with the first factor referring to two samples of red latosols, one eutrophic (LV1) and the other dystrophic (LV2), and the second factor was soil’s pH, at six levels: 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5. Samples were incubated for 70 days in laboratory conditions. Both nitrate (N-NO3) and mineral N contents were determined and adjusted to growth models. The eutrophic soil presented higher mineral N and N-NO3, and the increase of pH levels led to increases of both inorganic N and N-NO3contents. Increases in pH levels caused N-NO3levels to increase in both soils, however this occurrence happened because it increased the amount of mineralized N in the soil, seen that in all pH ranges in both soils practically all mineral N was in the form of N-NO3.

Rhizosphere mediated biodegradation of benzo(A)pyrene by surfactin producing soil bacilli applied through Melia azedarach rhizosphere

Benzo(a)pyrene is a high-molecular-weight polycyclic aromatic hydrocarbon highly persistent in the environment as a biohazard. The present research emphasizes on rhizodegradation of BaP using bacterial isolates, Bacillus flexus S1I26 (NCBI accession no- KX692271), and Paenibacillus sp. S1I8 (KX602663) with plant Melia azedarach. The isolates produced surfactin type bio-surfactant with high emulsification index that could solubilize BaP efficiently. The extracted crude bio-surfactants could solubilize BaP up to 24.41%, which was higher than the efficiency of synthetic surfactant SDS (9.7%) but less than other synthetic surfactant, tweens 80 (42.79%). The isolates showed excellent degradation of BaP after 21 days in laboratory conditions where B. flexus S2I26 showed degradation of BaP up to 70.7% and isolates Paenibacillus sp. S1I8 showed degradation rate of 76.76% in a liquid medium. Pot trial experiment showed efficient rhizodegradation of BaP in the soil after 60 days in the rhizosphere of plant Melia azedarach. After application of S1I8 and S1I26, the rate of degradation was found to be much higher (87.42 and 86.08%) than in bulk (68.22%). Therefore, the results suggest that the bio-surfactant producing isolates could be a promising biodegradation tool for benzo(a)pyrene in soil and may be used for bioremediation of hydrocarbon contaminated sites.

Efficacy of Herbicide Glyphosate Hijack® on the Blood Parameters of the Freshwater Fish, Catla catla (HAM)

The present study was carried out to study of the haematology of the freshwater fish, Catla catla were exposed to herbicide glyphosate hijack® for 10, 20 and 30 days in laboratory condition. Several haematological changes such as RBC, WBC, HB, HCT, Blood Glucose, Total Cholesterol, Triglycerides, Total Protein were observed in fish blood would serve as a useful purpose in evaluating the toxic effects of herbicide glyphosate hijack® (41%). All the values were significantly decreased from control. The maximum decreased level of activities in all these blood values was at 30 days. It has been concluded that herbicide glyphosate hijack ® (41%) at sub-lethal concentration may alter the RBC, WBC, HB, HCT, total glucose, total cholesterol, triglycerides and total protein in blood in all the exposure periods.

Evaluation of tolerance to Phytophthora capsici-the causal agent of foot rot disease in black pepper

Vietnam is the leading black pepper export country in the world. However, the production of pepper may be affected by natural disasters, pests such as Phytophthora capsici. The Phytophthora capsica disease has caused a significant decline in pepper yields. The disease is characterized with a high mortality rate (up to 100%) and rapid outbreak and thus is very challenging to control. In the present study, eight strains of P. capsici were isolated from 100 samples of leaf, stem, root and soil that were collected from pepper-growing areas of Dong Nai, Binh Duong and Ba Ria - Vung Tau provinces. These isolates' straits had capacity to cause foot rot on pepper leaf after two days of inoculation. Among them, the isolates with the highest pathogenicity are BR-L1, DN-D1 and DN-D2. In order to determine the resistance level to P. capsici of commonly grown pepper varieties (Vinh Linh, Se, Xanh, Trau and Kuching), the pepper leaves were in vitro infected with P. capsici BR-L1 spores in laboratory and greenhouse conditions. Trau variety showed the highest resistance level to P. capsici with the as indicated by (P < 0.01) disease ratio (74.1%) and disease index (73.7%) after 6 days in laboratory condition and the corresponding numbers of 17.3% and 15.8% after 12 days in greenhouse condition.

Effects of chemotherapeutics against experimentally injured stinging catfish Heteropneustes fossilis

Effects of different chemotherapeutics were examined against experimentally infected stinging catfish Heteropneustes fossilis. Fish were collected from a fish market in Mymensingh, acclimatized for 7 days in laboratory condition from January to February, 2016 in aquaria at Fish Clinic of Bangladesh Agricultural University, Mymensingh, experimentally injured by using forceps and knife and waited seven days for the establishment of infection. Before starting chemotherapeutic trial, it was confirmed that the fish were infected with microorganisms by clinical diagnosis in laboratory condition. They showed hemorrhages and ulcerative lesions over the infected area. A total of 80 such experimentally infected stinging catfish having average body weight of 18 g were used for the experiment. Two chemotherapeutics: antibiotic, Eryvet (erythromycin thiocyanate INN, sulphadiazine (NaUSP) & trimithoprim BP) and antifungal, methylene blue were used in separate and combined treatment with three different doses of antibiotic. The same dose of methylene blue, 0.2 mg/l, was used for separate and combined treatment by antibiotic. Doses of antibiotic (Eryvet) were 0.8 g/10 kg body weight of fish, 1g/10 kg body weight of fish and 1.2 g/10 kg body weight of fish as lower dose, recommended dose and higher dose respectively. For combined treatment the above different doses of antibiotic and the same dose of antifungal were used. Water was exchanged regularly. The chemotherapeutic trial was conducted for 7 days and observation was continued for another 8 days to observe the effect of treatment. Combined treatment with the recommended dose of the antibiotic and methylene blue showed the best result where 90% fish were recovered. By the treatment with the higher dose of the antibiotic 70% fish were recovered. Antifungal treatment showed that 20% fish were recovered. All the fish in negative control aquarium died.Asian J. Med. Biol. Res. December 2017, 3(4): 476-487

Laboratory Study of the Effect of Degrees of Saturation on Lime Concrete Resistance Due to the Groundwater Level Increment

Lime concrete and lime treatment are two attractive techniques for geotechnical engineers in the construction of rail tracks and pavement layers, in slope protection of earth dams, and as a support layer for shallow foundations. The present study investigates the influence of different degrees of saturation upon the unconfined compressive strength (qu) of lime concrete. At first, the characteristics of used materials were determined. Then, the optimum amounts of water and clay soil were determined based on flow table tests and uniaxial compression tests. Specimens with an optimum level of clay, sand, lime, and moisture were prepared. After processing durations of 14, 28, 45, and 60 days in laboratory condition, the specimens were exposed to saturation levels ranging from 0 to 100%. The uniaxial compressive strength tests were then carried out on all specimens. The diagram of strength reduction of lime concrete versus different depths and saturation degrees (Sr) were developed. The results showed that the moisture has a significant effect on decreasing the strength of lime concrete. The specimens that placed in 100% of saturated condition failed completely, and in 20% of saturated condition, the strength value of specimens decreased about 42%. Also, the optimum percentages of clay and water for application in lime concrete with 7% lime, respectively 23 and 24.04% were determined. Based on the results of SEM test it was observed that the specimen was characterized by a rather well-structured matrix since both the filling of a large proportion of the coarse-grain soil voids by clay and the pozzolanic activity of lime led to retain less pore water in the specimen, increasing the uniaxial compressive strength, and consequently resist against swelling and shrinkage of the clay soil.

Open porosity of cement pastes and their gas permeability

AbstractThis paper presents the results of extensive research work on the open porosity and gas permeability of cement pastes. Tests were conducted on cement pastes with different water/cement ratios and types of cement. The three most popular cements in Poland from the CEM I, CEM II and CEM III groups were tested after the pastes had been cured for 90 days in laboratory conditions. The scope of experiments included the assessment of open porosity determined using three different methods: comparing the bulk and specific densities, mercury intrusion porosimetry and saturating the material with water. In addition, this article contains an analysis of the porosity characteristics based on the distributions produced by porosimetry examinations. Gas permeability was determined using the modified RILEM-Cembureau laboratory method. The results of the completed test allowed a quantitative determination to be made of the impact of water-cement ratio and type of cement used on open porosity assessed by various methods, and the influence of these parameters on the gas permeability of the paste. The quantitative changes in the content of capillary pores and meso-pores in the cement pastes analysed are also presented.

Soil Fertility and Electrical Conductivity Affected by Organic Waste Rates and Nutrient Inputs

The composition of organic waste (OW) and its effect on soil processes may change soil fertility and electrical conductivity (EC). The side effects of waste use in crop fertilization are poorly understood for Brazilian soils. This study examined the effect of the addition of 15 different organic wastes to Oxisols and a Neosol on pH, base saturation, EC, cation exchange capacity (CEC at pH 7), and the availability of Al, macro (P, K, Ca2+, Mg2+ and S) and micronutrients (B, Fe2+, Mn2+, Cu2+ and Zn2+). Soil samples (150 g) were treated with chicken, pig, horse, cattle, and quail manures, sewage sludge 1 and 2, eucalyptus sawdust, plant substrate, coconut fiber, pine bark, coffee husk, peat, limed compost, and biochar. Wastes were added considering a fixed amount of C (2 g kg-1), which resulted in waste rates ranging from 2.5 to 25.6 Mg ha-1. The soil-waste mixtures were incubated for 330 days in laboratory conditions. The waste liming or acidification values were soil-dependent. The use of some manures and compost increased the pH to levels above of those considered adequate for plant growth. The soil EC was slightly increased in the Neosol and in the medium textured Oxisol, but it was sharply changed (from 195 to 394 µS cm-1) by the addition of organic wastes in the clayey Oxisol, although the EC values were below the range considered safe for plant growth. Changes in the soil availability of P, K+, Ca2+ and Zn2+ were highly related to the inputs of these nutrients by the wastes, and other factors in soil changed due to waste use. Organic waste use simultaneously affects different soil fertility attributes; thus, in addition to the target nutrient added to the soil, the soil acidity buffering capacity and the waste liming and agronomic value must be taken into account in the waste rate definition.

Variation in trace element mobility and nitrogen metabolism of Verbascum olympicum Boiss. under copper stress

The aim of this study was to evaluate the effects of copper (Cu) stress on accumulation and transport of trace elements, nitrogen assimilation, and growth parameters of Verbascum olympicum. Eight-week-old seedlings were grown in Hoagland's solution and exposed to 0, 50, 250, or 500 µM CuSO4 for seven days in laboratory conditions. Bioaccumulation of trace elements (boron, bismuth, cobalt, Cu, iron, lithium, manganese, molybdenum, nickel, lead, zinc) in the roots and leaves was determined by inductively coupled plasma–mass spectrometry after one, three, and seven days. Chlorophyll content, nitrate reductase, and glutamine synthetase activities, soluble protein content, and biomass were determined. Copper accumulated in the roots and leaves (up to 19609.8 and 256.2 mg kg−1 dry weight, respectively). Other trace elements accumulated to higher levels in the roots of Cu-treated plants compared with those of control plants. High Cu concentrations decreased nitrogen-assimilatory enzyme activities. Compared with control plants, those treated with high Cu concentrations showed lower chlorophyll contents, total protein contents, and biomass. Nitrogen assimilation and growth parameters of V. olympicum were negatively affected by Cu treatment but mineral nutrition was not severely disrupted. The results support the suitability of V. olympicum as a candidate for phytoremediation of Cu-contaminated soils.

Optimization of feeding frequency on the growth performance of thai pangas, Pangasius hypophthalmus (Sauvage, 1878)

Thai pangas, Pangasius hypophthalmus fingerlings were reared for 60 days in laboratory condition to investigate the effects of feeding frequency on the growth performance. The fish fingerlings in three treatments were fed with two, three and four times a day, respectively. During the feeding trial, growth and feed utilization were assessed by condition factor (K), average daily gain (ADG), specific growth rate (SGR) and feed conversion ratio (FCR). Significantly lower FCR 1.81 ± 0.02 and higher ADG 0.38 ± 0.02 and SGR 2.20 ± 0.02% were found in fish fed thrice a day than that of other treatments (p < 0.05). Highest condition factor 1.69 ± 0.13 was found in fish fed four times a day while the lowest condition factor 0.77 ± 0.03 was detected in fish fed twice a day. Moisture content of Thai pangas in treatment T1, T2 and T3 were 79.23 ± 0.77, 78.08 ± 0.85 and 77.84 ± 0.17%, respectively. The crude protein, crude lipid and ash contents were 16.11 ± 0.00 to 16.38 ± 0.08%, 3.22 ± 0.27 to 3.41 ± 0.06% and 1.47 ± 0.02 to 1.82 ± 0.04%, respectively. The findings of the present study demonstrated that three times feeding frequency showed better growth performance and nutritional composition of Thai pangas fingerlings.
 Dhaka Univ. J. Biol. Sci. 24(1): 83-90, 2015 (January)

Study of the efficacy of a Wheaton coated bottle with permethrin and deltamethrin in laboratory conditions and a WHO impregnated paper with bendiocarb in field conditions

To determine the efficacy of WHO impregnated paper and CDC coated bottle based on number of storage days and number of times of consecutive use, in the assessment of insecticide vector susceptibility tests in laboratory and field conditions. Larvae and pupae of Anopheles gambiae s.l. mosquitoes were collected from the breeding sites in Seme-Kpodji and Cotonou districts in Southern Benin in April 2013 during the first rainy season. Anopheles gambiae s.l. mosquitoes were also collected from the breeding sites in Parakou district in Northern Benin in May 2013 at the beginning of the rainy season. Susceptibility tests were done using impregnated paper with bendiocarb (0.1%) following WHO protocol and stock solutions of permethrin (21.5 µg per bottle) and deltamethrin (12.5 µg per bottle) following CDC protocol on unfed female mosquitoes aged 2-5 days old. These bioassays were repeated a certain number of times. The temperature and relative humidity were monitored and recorded during the susceptibility tests. This study showed that a WHO impregnated paper with bendiocarb could be used four times during four consecutive days in field conditions. Regarding a Wheaton coated bottle with permethrin or deltamethrin, they could be used at least three times during four consecutive days in laboratory conditions. The day storage and the number of times that a WHO impregnated paper and a CDC coated bottle maintained their efficacy are useful in the assessment of insecticide vectors susceptibility tests.

Online Detection of Metals in Environmental Samples: Comparing Two Concepts of Bioluminescent Bacterial Biosensors

In this study, we compared two bacterial biosensors designed for the environmental monitoring of metals: Lumisens III and Lumisens IV. These two biosensors are based on the same bacterial sensors (inducible or constitutive bacterial strains) but with a different conservation mode. The results showed that the biosensor Lumisens III using immobilized cells in agarose hydrogel, allowed to detect artificial mercury contaminations on the limited period of 7 days in laboratory conditions with a reproducibility of 40%. With environmental samples, bioluminescence of the immobilized bacteria inside the biosensor was strongly limited by the environmental microflora because of the lack of oxygen, limiting the use of the biosensor to 2 days. The biosensor of the last generation, Lumisens IV, using freeze-dried bacteria in a disposable card allowed a stable detection during 10 days with 3% of reproducibility of the bioluminescence signal both in laboratory conditions and environmental samples. One analysis was performed in only 90 min against 360 min for Lumisens III. Nevertheless, the lack of specificity of the promoter, which regulates the bioluminescent reporter genes, limits the metal detection. We addressed the problem by using Lumisens IV and a data analysis software namely Metalsoft, developed in previous works. Thanks to this analytical software, Lumisens IV was a reliable online biosensor for the multidetection of Cd, As, Hg, and Cu.