Bioassay Technique Research Articles

Unpacking WHO and CDC Bottle Bioassay Methods: A Comprehensive Literature Review and Protocol Analysis Revealing Key Outcome Predictors

Background Resistance monitoring is a key element in controlling vector-borne diseases. The World Health Organization (WHO) and Centres for Disease Control and Prevention (CDC) have each developed bottle bioassay methods for determining insecticide susceptibility in mosquito vectors which are used globally. Methods This study aimed to identify variations in bottle bioassay methodologies and assess the potential impact on the data that is generated. Our approach involved a systematic examination of existing literature and protocols from WHO and CDC, with a focus on the specifics of reported methodologies, variation between versions, and reported outcomes. Building on this, we experimentally evaluated the impact of several variables on bioassay results. Results Our literature review exposed a significant inconsistency in the how bioassay methods are reported, hindering reliable interpretation of data and the ability to compare results between studies. The experimental research provided further insight by specifically identifying two key factors that influence the outcomes of bioassays: mosquito dry weight and relative humidity (RH). This finding not only advances our comprehension of these assays but also underscores the importance of establishing precisely defined methodologies for resistance monitoring. The study also demonstrates the importance of controlling bioassay variables, noting the significant influence of wing length, as an indicator of mosquito size, on mortality rates in standardized bioassays. Conclusions Generating data with improved protocol consistency and precision will not only deepen our understanding of resistance patterns but also better inform vector control measures. We call for continued research and collaboration to refine and build consensus on bioassay techniques, to help bolster the global effort against vector-borne diseases like malaria.

Strategies for identification of elite Hevea brasiliensis genotypes tolerant to ALF disease from half-sib and full-sib population

Natural Rubber (NR) from Hevea brasiliensis tree is an important commercial commodity worldwide. In general, many Hevea cultivars are vulnerable to abnormal leaf fall (ALF) disease caused by Phytophthora spp., which can lead to considerable reduction in crop production. Chemical control of ALF by spraying mineral oil-based copper fungicides is the conventional approach which is harmful to the ecosystem. Development of ALF tolerant varieties of Hevea through conventional breeding is the major objectives of this study. We evaluated the primary agronomy traits and ALF tolerance level of the newly developed Hevea clones using in vitro leaf disc bioassay as well as field screening for disease incidence consecutively for three years. Variation in disease infestation was observed among genotypes. Based on field screening, the clones which showed better field tolerance against ALF than the parental clones were selected. Clone 683 was identified as one of the most desirable genotypes which had vigorous growth as well as high crop yield in addition to ALF tolerance. The study also confirms the reliability of in vitro leaf disc bioassay technique for screening against ALF across genotypes for its inherent variability. This technique is rapid and easier and can be completed within 96 hours. This approach could reduce the burden of screening larger breeding population to a manageable size to enhance the efficiency of selection in ALF disease resistance breeding programs. Selected fast growing, high yielding ALF tolerant clones, could be further evaluated in on farm trials for recommending to the growers in the traditional region of rubber growing tracts.

Assessment of emerging and persistent contaminants in an anthropogenic-impacted watershed: Application using targeted, non-targeted, and in vitro bioassay techniques

Emerging and persistent contaminants (EPC) pose a significant challenge to water quality monitoring efforts. Effect-based monitoring (EBM) techniques provide an efficient and systematic approach in water quality monitoring, but they tend to be resource intensive. In this study, we investigated the EPC distribution for various land uses using target analysis (TA) and non-target screening (NTS) and in vitro bioassays, both individually and integrated, in the upper Ping River Catchment, northern Thailand. Our findings of NTS showed that urban areas were the most contaminated of all land use types, although agriculture sites had high unexpected pollution levels. We evaluated the reliability of NTS data by comparing it to TA and observed varying inconsistencies likely due to matrix interferences and isobaric compound interferences. Integrating NTS with in vitro bioassays for a thorough analysis posed challenges, primary due to a scarcity of concentration data for key compounds, and potentially additive or non-additive effects of mixture samples that could not be accounted for. While EBM approaches place emphasis on toxic sites, this study demonstrated the importance of considering non-bioactive sites that contain toxic compounds with antagonistic effects that may go undetected by traditional monitoring approaches. The present work emphasizes the importance of improving NTS workflows and ensuring high-quality EBM analyses in future water quality monitoring programs.

Fast Assessment of Quality of Water Containing Inorganic Pollutants Using Laser Biospeckles in Microbioassay

Recently, bioassay techniques have been gaining prominence in assessing water toxicity, offering comprehensive evaluations without identifying the individual chemical component. However, microscopic observation is a crucial component in microbioassays to know the critical features of the targeted microorganisms. However, as the microorganism’s size becomes smaller, observation becomes more difficult due to the narrower focal depth of the imaging system. To address this challenge, we propose a novel laser biospeckle non-imaging technique utilizing biospeckle patterns generated by microorganisms, enabling non-imaging assessments of their swimming ability. Paramecium and Euglena were used as microorganisms. Paramecium and Euglena were subjected to varying concentrations of heavy metal pollutants (Zn(NO3)2·6H2O and FeSO4·7H2O), and their swimming activity was quantified using a dynamic biospeckle analysis. The results show a concentration-dependent effect of Zn on both species, leading to decreased swimming ability at increased concentration. Conversely, Fe exhibited varying effects on Paramecia and Euglena, with the latter displaying tolerance at lower concentrations but a notable response at higher concentrations. The advantage of the method is that owing to the non-imaging system, an enormous number of microorganisms can be processed. Moreover, the method allows for an immediate and statistically significant estimation of their swimming ability in response to environmental pollution.

Unpacking WHO and CDC Bottle Bioassay Methods: A Comprehensive Literature Review and Protocol Analysis Revealing Key Outcome Predictors.

Resistance monitoring is a key element in controlling vector-borne diseases. The World Health Organization (WHO) and Centres for Disease Control and Prevention (CDC) have each developed bottle bioassay methods for determining insecticide susceptibility in mosquito vectors which are used globally. This study aimed to identify variations in bottle bioassay methodologies and assess the potential impact on the data that is generated. Our approach involved a systematic examination of existing literature and protocols from WHO and CDC, with a focus on the specifics of reported methodologies, variation between versions, and reported outcomes. Building on this, we experimentally evaluated the impact of several variables on bioassay results. Our literature review exposed a significant inconsistency in the how bioassay methods are reported, hindering reliable interpretation of data and the ability to compare results between studies. The experimental research provided further insight by specifically identifying two key factors that influence the outcomes of bioassays: mosquito dry weight and relative humidity (RH). This finding not only advances our comprehension of these assays but also underscores the importance of establishing precisely defined methodologies for resistance monitoring. The study also demonstrates the importance of controlling bioassay variables, noting the significant influence of wing length, as an indicator of mosquito size, on mortality rates in standardized bioassays. Generating data with improved protocol consistency and precision will not only deepen our understanding of resistance patterns but also better inform vector control measures. We call for continued research and collaboration to refine and build consensus on bioassay techniques, to help bolster the global effort against vector-borne diseases like malaria.

Efficacy of aqueous and alcoholic formulations extracted from Padina boryana algae against Aedes aegypti mosquito larvae: A comparative study

AbstractAedes aegypti is a mosquito species known for transmitting several diseases, with dengue fever being of utmost importance. Controlling the spread of dengue fever remains a significant global health challenge. Other diseases transmitted by Ae. aegypti include Zika virus, chikungunya, and yellow fever. Padina boryana algae were collected from the Red Sea coast south of Jeddah to evaluate the effectiveness of its alcoholic and aqueous extracts against Ae. aegypti mosquito larvae. The algae sample was washed, dried in the shade, processed, and subjected to aqueous and alcohol extraction using a rotary evaporator. The resulting extracts were tested for their larvicidal activity against Ae. aegypti mosquito larvae using standard bioassay techniques. The larval mortality rates were recorded, and the lethal concentration (LC50 and LC90) values were calculated.The results revealed that both the aqueous and alcoholic extracts of P. boryana algae exhibited significant larvicidal activity against Ae. aegypti mosquito larvae. However, the alcoholic formulation demonstrated higher efficacy compared to the aqueous formulation. The LC50 values for the alcoholic and aqueous extracts were 194.8 and 195.7 ppm, respectively. The LC90 values for both extracts were 653.1 and 656.7 ppm, respectively. This indicates the effectiveness of Padina extracts as an effective pesticide against the larvae of the Ae. aegypti mosquito. Overall, the alcohol extract showed promising efficacy, indicating its potential as a significant component in developing effective mosquito control strategies.

Green chemistry approach for rapid synthesis of indol-3-yl-4H-pyran derivatives, biological assessments, and toxicological activities against Cowpea aphid (Aphis craccivora)

From diverse or indole-3-carbaldehyde, certain unique indol-3-yl-4H-pyran derivatives were generated by condensing with different nucleophiles. IR, 1HNMR, and elemental studies have all confirmed their chemical structures. The green catalyst for the formation of indol-3-yl-4H-pyran derivatives is a zinc-linked amino acid complex [Zn(L-proline)2]. Furthermore, the environmental friendliness of this synthetic technique was investigated by assessing the reusability of the Zn(L-proline)2 complex over five consecutive cycles with no significant loss of catalytic activity. This novel process has showed substantial advantages in terms of safety, simplicity, stability, mild conditions, a short reaction time, excellent yields, and good purity without the use of organic solvents. The antibacterial properties of the compounds produced were investigated and discovered to be promising. To determine whether compounds are appropriate as possible insecticidal agents, the toxicological activity of the synthesized compounds against Cowpea aphid, Aphis craccivora, was tested using leaf dip bioassay technique toxicity studies performed in the laboratory. KEY WORDS: One pot synthesis, Zn(L-proline)2, Indole-3-carbaldehyde, Aqueous media, Microwave irradiation, Cowpea aphid, toxicological activity Bull. Chem. Soc. Ethiop. 2024, 38(4), 1077-1090. DOI: https://dx.doi.org/10.4314/bcse.v38i4.21

Prospecting the Effectiveness of Fungicides and Bioagents against Colletotrichum gloeosporioides (Penz.) Penz & Sacc.

Aims: The leaf spot caused by Colletotrichum gloeosporioides (Penz.) Penz & Sacc. is one of the most serious disease in all mango growing regions of the world. In vitro bioassay of fungicides and bioagents were performed to evaluate the effectiveness of different fungicides and bioagents against C. gloeosporioides.
 Study Design: Poison food techique for fungicides bioassay and dual culture technique for bioagents bioassay.
 Place and Duration of Study: The laboratory studies were conducted in the Department of Plant Pathology, N. M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat, India during 2020–2021.
 Methodology: The poison food technique assessed the efficacy of systemic, contact and combination fungicides against C. gloeosporioides. While the dual culture method was employed to gauge the potency of biocontrol agents, against C. gloeosporioides. 
 Results: In laboratory screening, systemic fungicides such as carbendazim and difenconazole were shown to have 100% growth suppression at 500 ppm. Mancozeb and copper oxychloride, two contact fungicides, demonstrated 100% growth inhibition of C. gloeosporioides at 2500 ppm . The combi-product fungicides tricyclazole 18% + mancozeb 62%, hexaconazole 4% + zineb 68%, and carbendazim 12% + mancozeb 63% were shown to exhibit 100% growth inhibition at 2000 ppm. Using the dual culture method, five distinct bioagents were tested in vitro for their ability to prevent the development of C. gleosporiodes. Trichoderma harzianum showed up as one of them to be a powerful and effective antagonist of C. gleosporiodes.
 Conclusion: In vitro fungicide and bioagent testing provides preliminary data on the effectiveness of fungicides against pathogens, guiding field testing. The study evaluated the effectiveness of fungicides and bioagents in suppressing the leaf spot pathogen of mango.

Synthesis of a Zn-MOF fluorescent material for sensitive detection of biothiols via an inner filter effect with MnO2 nanosheets.

In this study, zinc ions were employed as the central metal, while 4,4',4''-nitrilotribenzoic acid (H3NTB) served as the fluorescent organic ligand. Through a single-step solvothermal approach, a novel Zn-based metal-organic framework (Zn-MOF) fluorescent material was successfully synthesized. The Zn-MOFs exhibit a cubic morphology, outstanding fluorescence properties, excellent water dispersibility, and robust resistance to high temperature and strong alkaline conditions. Additionally, MnO2 nanosheets (NSs) were effectively exfoliated from MnO2 particles using ultrasonic treatment. These MnO2 NSs possess a broad UV-Vis absorption band that overlaps with the fluorescence spectra of Zn-MOFs. Leveraging the inner filter effect (IFE) between MnO2 and Zn-MOFs, a Zn-MOF-based fluorescence bioassay technique was developed for the detection of biothiols. The results demonstrate that this Zn-MOF-based fluorescence detection platform exhibits a remarkable sensitivity towards biothiols, achieving a detection limit of 0.067 μM, surpassing that of other reported MnO2-based detection methods. Furthermore, this detection platform has been successfully applied to the quantitation of glutathione (GSH) in human serum, highlighting its potential for highly sensitive and specific detection of biothiols.

Cascade Amplified Plasmonics Molecular Biosensor for Sensitive Detection of Disease Biomarkers.

Recent advances in molecular technologies have provided various assay strategies for monitoring biomarkers, such as miRNAs for early detection of various diseases and cancers. However, there is still an urgent unmet need to develop practical and accurate miRNA analytical tools that could facilitate the incorporation of miRNA biomarkers into clinical practice and management. In this study, we demonstrate the feasibility of using a cascade amplification method, referred to as the "Cascade Amplification by Recycling Trigger Probe" (CARTP) strategy, to improve the detection sensitivity of the inverse Molecular Sentinel (iMS) nanobiosensor. The iMS nanobiosensor developed in our laboratory is a unique homogeneous multiplex bioassay technique based on surface-enhanced Raman scattering (SERS) detection, and was used to successfully detect miRNAs from clinical samples. The CARTP strategy based on the toehold-mediated strand displacement reaction is triggered by a linear DNA strand, called the "Recycling Trigger Probe" (RTP) strand, to amplify the iMS SERS signal. Herein, by using the CARTP strategy, we show a significantly improved detection sensitivity with the limit of detection (LOD) of 45 fM, which is 100-fold more sensitive than the non-amplified iMS assay used in our previous report. We envision that the further development and optimization of this strategy ultimately will allow multiplexed detection of miRNA biomarkers with ultra-high sensitivity for clinical translation and application.

Bioassay Techniques in Entomological Research

BIOASSAY (Bio - life, Assay - determination) is the measurement of the potency of any stimulus (physical, chemical, biological, and psychological) and the reactions that it produces in living matter. In Entomology, to know about the potency, Specificity of any compounds, standardization of doses, and identify modes of action bioassay is needed. In addition to the basic bioassay methods such as poison food, dry film techniques, etc., depending upon the researcher’s necessity, they are modified or newly developed. Diet covering and diet incorporation for lepidopterans and homopterans have been developed as advancements over the poison food assay method, by using insecticide-incorporated artificial diet. WHO cone, Wire ball test, Susceptibility test, CDC bottle assay and MCD assay developed for mosquito resistance monitoring and Larval Packet Technique (LPT) for cattle ticks, Sandwich method, TIBS, and Adult vial test are advancements over dry film technique. In Thrips Insecticide Bioassay System (TIBS), treated vials can be stored for up to 3 weeks at 4˚C for future efficacy assays at the field level. Adult Vial Tests have been developed for pentatomid and mirid adult bug bioassays. Larval Immersion Technique (LIT), Adult Immersion Technique (AIT) for cattle ticks, and MEBS have been developed as advancements over topical bioassay. In Mite Egg Bioassay System (MEBS), entomopathogenic fungi have been tested against Tetranychus cinnabarinus. MTT colorimetric assay and Trypan Blue Dye Exclusion assay helps to identify cell viability in insect cell line cultures. Spodoptera frugiperda cell line, Sf – 21 was tested against a scorpion, Leiurus quinquestriatus toxin β– BUTX – LQQ1a and the toxicity was determined through the viability of cell lines. Various basic and advanced bioassay techniques are discussed elaborately in this review.

Influence of temperature on the toxicity and stability of insecticide resistance against Spodoptera littoralis (Lepidoptera: Noctuidae)

BackgroundSpodoptera littoralis Boisad. (Lepidoptera: Noctuidae) is an important pest causing significant losses to agricultural crops worldwide. Management practices for this insect pest rely on insecticides applications throughout the entire season over wide ranging temperature. However, studies involving the development of resistance in S. littoralis against these insecticides at different temperatures are limited.MethodsUsing leaf-dipping bioassay technique, the effect of temperature (range, 15–30 °C) on the toxicity of spinosad, lambda-cyhalothrin and methomyl, and resistance development was evaluated in larvae S. littoralis.ResultsSpinosad, lambda-cyhalothrin and methomyl exhibited increased toxicity with increasing temperature from 15 to 30 °C. The results indicated a successive decrease in insecticide resistance at the temperatures of 15, 20, 25 and 30 °C from 1st to 12th generations of S. littoralis to spinosad, lambda-cyhalothrin and methomyl.ConclusionsThis study suggests that spinosad, lambda-cyhalothrin, and methomyl can be included in the management of S. littoralis.

Infant botulism: a descriptive study in a pediatric intensive care unit

Introduction. Infant botulism (IB) is the most common form of human botulism in Argentina. Our objective was to describe the main aspects of diagnosis and management of patients with IB admitted to the pediatric intensive care unit (PICU). Methods. Observational, descriptive, and retrospective study. The PICU database with IB diagnosis in 2005-2020 period was used. Demographic variables, diagnostic methods, days of conventional mechanical ventilation (CMV), non-invasive ventilation (NIV), length of stay in the PICU and mortality upon hospital discharge were recorded. Results. In total, 21 patients with IB were recorded; 14 were male, their median age was 5 months (IQR: 2-6m). Diagnosis was made by bioassay, and the toxin was identified intheserumof12patients.Only1 patient did not require CMV; 1 patient had a tracheostomy; 18 patients received antibiotics; 5 received NIV. No patient was administered antitoxin and no patient died. The median length of stay in the hospital was 66 days (IQR: 42-76); in the PICU, 48 days (IQR: 29-78); and the median use of CMV, 37 days (IQR:26-64).Thedelayuntildiagnosticconfirmationwas15.8±4.8days. Conclusions. All patients were diagnosed using the bioassay technique, which resulted in a diagnostic delay that exceeds the recommended period for the administration of a specific treatment. No patient received a specific treatment. IB was related to a low mortality, but also to prolonged use o MV and length of hospital stay, which were associated with cross infections and frequent antibiotic use.

Insecticide resistance management of Bemisia tabaci (Hemiptera: Aleyrodidae) in Australian cotton - pyriproxyfen, spirotetramat and buprofezin.

Bemisia tabaci is a globally significant agricultural pest including in Australia, where it exhibits resistance to numerous insecticides. With a recent label change, buprofezin (group 16), is now used for whitefly management in Australia. This study investigated resistance to pyriproxyfen (group 7C), spirotetramat (group 23) and buprofezin using bioassays and available molecular markers. Bioassay and selection testing of B.tabaci populations detected resistance to pyriproxyfen with resistance ratios ranging from 4.1 to 56. Resistance to spirotetramat was detected using bioassay, selection testing and sequencing techniques. In populations collected from cotton, the A2083V mutation was detected in three populations of 85 tested, at frequencies ≤4.1%, whereas in limited surveillance of populations from an intensive horticultural region the frequency was ≥75.8%. The baseline susceptibility of B.tabaci to buprofezin was determined from populations tested from 2019 to 2020, in which LC50 values ranged from 0.61 to 10.75 mg L-1 . From the bioassay data, a discriminating dose of 200 mg L-1 was developed. Recent surveillance of 16 populations detected no evidence of resistance with 100% mortality recorded at doses ≤32 mg L-1 . A cross-resistance study found no conclusive evidence of resistance to buprofezin in populations with high resistance to pyriproxyfen or spirotetramat. In Australian cotton, B.tabaci pest management is challenged by ongoing resistance to pyriproxyfen, while resistance to spirotetramat is an emerging issue. The addition of buprofezin provides a new mode-of-action for whitefly pest management, which will strengthen the existing insecticide resistance management strategy. © 2023 Commonwealth of Australia. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

METHOD DEVELOPMENT AND VALIDATION FOR QUANTIFICATION OF OZENOXACIN IN PHARMACEUTICAL PRODUCTS BY MICROBIOLOGICAL ASSAY

Ozenoxacin is a novel non-fluorinated topical antibiotic belonging to the quinolone family. HPLC techniques are normally used for the quantification of the efficacy of ozenoxacin, however, the HPLC technique is unable to infer bioactivity against microorganisms. The goal of this article was to augment and authenticate an accurate, sensitive, and yet simple, commercial two-stage cylinder plate (2+2) assay for determining the efficacy and bioactivity of ozenoxacin in pharmaceutical products, which has not been published in any of the scientific journals. This study is based on the development of a bioassay technique for estimating ozenoxacin in pharmaceutical products. In this investigation, the microbiological assay was performed with 08 bacterial strains and 02 fungal strains, from which Salmonella enterica serotype Abony MTCC-3858 was selected as the most suitable organism against ozenoxacin based on sharp and clear zone of inhibition. The advanced mathematical approach to linearity, precision and accuracy has been successfully verified and validated. The mean potency recovery value was estimated to be 100.83 % for ozenoxacin cream. In this study, validated methods were used to assess the linearity (r2 =0.9859); the intermediate precision RSD between days was 1.01 %; The mean precision RSD between analysts was 1.04 % and accuracy was 100.67 %, RSD = 0.65 %. Bioassay was optimized by investigating several factors such as robustness by buffer diluent used for standard and sample preparation (phosphate buffer pH 8.0; RSD=0.37 %), inoculum concentration (0.3 %; RSD=0.44 %) and incubation temperature (30 o C; RSD=0.80 %). The result shows that the efficacy of ozenoxacin in pharmaceutical products can be estimated by bioassay technique for quality control purpose.

Presence of Spodoptera frugiperda Multiple Nucleopolyhedrovirus (SfMNPV) Occlusion Bodies in Maize Field Soils of Mesoamerica.

The occlusion bodies (OBs) of lepidopteran nucleopolyhedroviruses can persist in soil for extended periods before being transported back on to the foliage for transmission to the host insect. A sensitive insect bioassay technique was used to detect OBs of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) in 186 soil samples collected from maize fields in the southern Mexican states of Chiapas, Tabasco, Campeche, Yucatán, and Quintana Roo, as well Belize and Guatemala. Overall, 35 (18.8%) samples proved positive for SfMNPV OBs. The frequency of OB-positive samples varied significantly among Mexican states and countries (p < 0.05). Between 1.7 and 4.4% of S. frugiperda larvae that consumed OB-positive samples died from polyhedrosis disease. Restriction endonuclease analysis using PstI and HindIII confirmed that the soil-derived isolates were strains of SfMNPV and that genetic diversity was evident among the isolates. The prevalence of OB-positive soil samples did not differ with altitude or extension (area) of the maize field, but it was significantly higher in fields with the presence of living maize plants compared to those containing dead plants or crop residues (p < 0.05). Georeferenced soil samples were used to identify soil types on digitized soil maps. Lithosol and Luvisol soils had a higher than average prevalence of OB-positive samples (42-45% positive) (p = 0.006), as did Andosol, Gleysol, and Vertisol soils (33-60% OB-positive), although the sample sizes were small (<5 samples) for the latter three soils. In contrast, Cambisol soils had a lower than average prevalence of OB-positive samples (5% positive). Bioassays on Acrisol, Fluvisol, Phaeozem, and Rendzina soils resulted in intermediate levels of OB-positive samples. We conclude that certain soil types may favor OB persistence and virus-mediated biological pest control. The soil is also likely to provide a valuable source of genetic diversity for the design of virus-based insecticides against this pest.

Larvicidal effects of some essential oils against Aedes aegypti (L.), the vector of dengue fever in Saudi Arabia

Essential oils are very popular among organic growers because they are ecologically safe, do not have mammalian toxicity, and cannot be resistant to a variety of contaminants. Four essential oils, Lemon, Lavender, Peppermint, and Neem, were tested for larvicide efficacy against the dengue fever vector Aedes aegypti larvae under laboratory conditions using dipping bioassay techniques. Among the essential oils tested, lemon, peppermint, and lavender oils showed high larvicidal activity against larvae of Ae. aegypti. Lemon oil showed the highest effects (LC50 10.676 ppm), while Peppermint, Lavender and Neem oil showed the lowest effects (LC50 21.380, 29.818 and 38.058 ppm, respectively). As a result, the mixture of lemon oil (LC50) with Peppermint oil (LC25) showed the highest co-toxicity factor, whereas the mixture of Lemon oil (LC50) with Diesel oil (LC25) showed the lowest co-toxicity factor. Based on the results of this study, it appears that essential oils may be useful as larvicides against Ae. aegypti larvae. In search of new natural larvicides, these compounds may provide an alternative to Synthetic insecticides as these are environmentally safe insecticides.

Laboratory Evaluation of Temperature Effects on Germination, Radial Growth and Sporulation of Entomopathogenic Fungi and on Their Pathogenicity to Red Spider Mite, Tetranychus urticae Koch

Background: Entomopathogenic fungus (EPF) can provide safe and efficient insect pest management. Temperature, relative humidity (RH), light, air, nutritional content and host physiological condition are all elements that impact the proliferation and virulence of entomopathogenic fungus. The current study aimed to evaluate the effect of different temperatures on germination, growth, sporulation of entomopathogenic fungi and on their pathogenicity against Tetranychus urticae Koch was studied. Methods: Laboratory experiment was conducted to study the impact of temperature on germination, radial growth and sporulation of five entomopathogenic fungal isolates viz., B. bassiana (Bb 111), B. bassiana (Bb 112), B. bassiana (Bb 113), B. bassiana (Bb 114) and M. flavoviride var. minus. Virulence of five entomopathogenic fungal isolates subjected to different temperature against T. urticae also evaluated through laboratory bioassay techniques. Result: Results one valuation of entomopathogenic fungal isolates with four different temperatures at 20°C, 25°C, 30°C and 35°C showed that 25°C was optimum for germination, radial growth and sporulation. Maximum germination was recorded with the entomopathogenic isolate Beauveria bassiana (Bb 112) (95.67%) at 25°C. Interestingly, at 25°C all the B. bassiana isolates showed a radial growth of more than 50 mm with the highest recorded as 84.67 mm by B. bassiana (Bb 111). Maximum spore production was observed with B. bassiana (Bb 112) at 25°C (1.63 x 106 spores ml-1) followed by B. bassiana (Bb 111) (1.45 x 106 spores ml-1). It was also the most pathogenic against T. urticae at 25 and 30°C. The isolate Bb112 grown at 25°C caused higher mortality of 97.57 per cent against T. urticae. From the findings the isolates of B. bassiana (Bb 112) and (Bb 111) were found promising bio control agent against T. urticae with varying temperature.

Detection of Toxoplasma gondii oocysts in soil and risk mapping in an island environment in the Northeast of Brazil.

Toxoplasmosis is an emerging and re-emerging infectious disease that can be transmitted through a contaminated environment. Environmental contamination is an emergency health issue, and determining its occurrence is fundamental to a One Health approach. In this study, we addressed the extent of environmental contamination and viability of Toxoplasma gondii oocysts in soil in different environments on Fernando de Noronha Island, Brazil. In addition, we performed species distribution modelling to predict the environmental suitability for coccidia persistence in the studied area. Soil samples were collected in 14 neighbourhoods of the Island and in the four main squares, creating a total of 95 soil samples (five samples per site). The samples were analyzed by the polymerase chain reaction (PCR) technique for the presence of the 18S ribosomal DNA gene of Apicomplexan protozoa, followed by genetic sequencing. We obtained 4.2% (4/95) positive soil samples with 100% similarity for T. gondii sequences. Two out of four positive sites on PCR showed viability of T. gondii oocysts through the mouse bioassay technique. As a result of the application of the species distribution modelling, environmental adequacy for the coccidia was observed throughout the Island. The results confirm the contamination of the soil in this insular environment by T. gondii oocysts and the environmental suitability by modelling application. These findings are an alert for the possibility of infection in animals and humans by contaminated soil, and for contamination of the maritime environment in addition to water resources for consumption by the local population.

Effect of Long Term Fertilization Practices on Tembotrione Movement in Soil: Assessment by Plant Bioassay

The herbicide behavior in soils is executed nowadays via the chemical extraction and instrumental analysis. However, the biological availability and the dynamics of herbicide in soil could be studied effectively through bioassay in the absence of sophisticated techniques and also in situ conditions. Tembotrione is one of the recently registered triketone herbicide and its movement behavior was not studied much in India. Hence the present study was executed to understand the influence of long term fertilization practices on its transport and movement using the bioassay technique involving Randomized Block Design (RBD). The plot wise soil samples were collected from the 50 years old long term fertilization experiment, processed and used to conduct the leaching column (made of PVC) experiment under controlled condition for 30 days. Soil samples were dissected depth wise and residue of tembotrione in each depth was obtained by conducting bioassay using green gram and sunflower as test species. For calibration curve preparation, a separate bioassay was conducted by fortifying tembotrione in control soil at different concentrations. The recorded plant parameters viz., germination percent and biomass after 15th day of both the test species predicted the tembotrione transport efficiently and the results of both the test species were comparable. The tembotrione has shown movement upto 30 cm soil depth and the concentration of residue decreased with increase in soil depth. The long term fertilization practices with the balanced nutrients supply viz., 100% NPK with hand weeding, Zn, FYM showed significant effect on the transport of tembotrione in soil at various depths.
 The study concludes that the plant bioassay technique using green gram and sunflower could be very well used to investigate the transport behavior of Tembotrione in soil. Based on data, tembotrione was identified as moderately mobile compound in sandy clay loam and its movement has been altered by the long term fertilization practices.