Agricultural Insecticides Research Articles

Health risk assessment of dermal exposure to Chlorpyrifos among children in agricultural areas in Sakon Nakhon Province, Thailand

Chlorpyrifos is a widely used agricultural insecticide. Chlorpyrifos exposure affects brain development and children’s overall health. The objective of this study was to assess the health risks from skin exposure to chlorpyrifos and to investigate the factors associated with chlorpyrifos exposure among children in agricultural areas. Residual chlorpyrifos samples were collected from the hands and feet of 130 children (aged 1–3) to analyze chlorpyrifos content using high-pressure liquid chromatography with a diode array detector. Chlorpyrifos residues were detected on the skin of 73.1% of the children tested. The health risk assessment of non-cancerous effects showed that children had dermal chlorpyrifos exposure at 1.46 × 10−5 mg/kg-day, and the hazard quotient (HQ) of child dermal chlorpyrifos exposure was 0.03, which is an acceptable level. The frequency of accompanying parents to pesticide-sprayed areas was significantly associated with dermal chlorpyrifos exposure levels in children (ORadjust =1.44, 95%CI =1.02–2.03). However, children in agricultural areas may be subject to additional health risks from exposure to other pesticides through respiration and ingestion. Therefore, they should not be allowed to accompany their parents to agricultural areas, and a program to prevent pesticides from affecting children in these areas should be developed.

Nitrile Hydratases: From Industrial Application to Acetamiprid and Thiacloprid Degradation.

The widespread application of neonicotinoid insecticides (NEOs) in agriculture causes a series of environmental and ecological problems. Microbial remediation is a popular approach to relieve these negative impacts, but the associated molecular mechanisms are rarely explored. Nitrile hydratase (NHase), an enzyme commonly used in industry for amide production, was discovered to be responsible for the degradation of acetamiprid (ACE) and thiacloprid (THI) by microbes. Since then, research into NHases in NEO degradation has attracted increasing attention. In this review, microbial degradation of ACE and THI is briefly described. We then focus on NHase evolution, gene composition, maturation mechanisms, expression, and biochemical properties with regard to application of NHases in NEO degradation for bioremediation.

Contributions of nearby agricultural insecticide applications to indoor residential exposures

BACKGROUND AND AIM: Pesticide exposure has been associated with adverse health effects; individuals may be exposed to pesticide drift from nearby agricultural fields. We evaluated relationships between agricultural insecticide applications and insecticide levels in carpet dust. METHODS: We measured concentrations (ng/g) of allethrin, azinphos-methyl, carbaryl, chlorpyrifos, cyfluthrin, cypermethrin, deltamethrin, diazinon, malathion, permethrin, phosmet, propoxur, tetramethrin in carpet-dust samples collected from 558 California homes. After using the California Pesticide Use Reporting database (reporting unit: ~2.59km2) to estimate agricultural insecticide use within buffers with radii of 0.5-, 1-, 2-, 3-, and 4km around each home, we calculated the density of use (kg/km2) during 30-, 60-, 180-, and 365-day periods prior to dust collection and evaluated relationships between insecticide density and concentrations in dust. We modeled natural-log transformed dust concentrations using Tobit regression for insecticides with 40% detection. For insecticides detected ≤40%, odds of detection were modeled with logistic regression. Models were adjusted for season, year, occupation, and home/garden uses. RESULTS:Detection frequencies ranged from 10% for allethrin, azinphos-methyl, and malathion to 80% for diazinon, chlorpyrifos, and permethrin. Chlorpyrifos applications within 1-4km of the residence during all time periods were associated with higher dust concentrations compared to homes without nearby applications. Carbaryl applications within 2-4km of homes 30- and 60-days prior to dust collection were associated with higher concentrations (30-days/2km, β any applications vs. none=8.2, 95%CI 1.8-37.6; 60-days/4km, β median density vs. none=4.2, 95%CI 1.1-15.7). Cyfluthrin and phosmet applications 180- and 365-days prior to dust collection were associated with higher odds of detection (365-days/4km, highest density vs. none: OR=2.2, 95%CI 1.2-4.0 and 6.2, 95%CI 3.3-12.0, respectively) compared to homes with no nearby use. CONCLUSIONS:Agricultural insecticide use within 4km of a home could be an important determinant of indoor contamination. Our findings provide valuable information for the development of exposure metrics for epidemiologic health studies. KEYWORDS: Pesticides, Exposures, Exposure assessment, Environmental epidemiology, Children's environmental health

Occurrence of pyrethroids in the atmosphere of urban areas of Southeastern Brazil: Inhalation exposure and health risk assessment

The occurrence of organochlorine pesticides (OCPs) used decades ago for vector control in urban areas is still reported as a threat to human health. Pyrethroids emerged as a replacement for OCPs in sanitary campaigns and are currently the main insecticides used for vector control worldwide, with prominent use as agricultural and household insecticides, for veterinary and gardening purposes, and as wood preservative. This study aimed to assess the occurrence, seasonal variation, and potential sources of pyrethroids in ambient air of two urban regions of Southeastern Brazil, along with the potential health risks to local populations via inhalation exposure. Pyrethroids were sampled by polyurethane foam passive air samplers and their concentrations were determined by gas chromatography coupled with electron capture negative ionization mass spectrometry (GC/ECNI-MS). Atmospheric pyrethroid concentrations (hereinafter reported in pg m−3) were considerably higher than those reported by previous studies worldwide. Cypermethrin (median: 2446; range: 461–15 125) and permethrin (655; 19–10 328) accounted for 95% of the total measured pyrethroids in ambient air. The remaining fraction comprised smaller amounts of bifenthrin (46; <limit of detection (LOD)–5171), deltamethrin (58; <LOD–564), phenothrin (7; <LOD–22) and fenvalerate (0.3; <LOD–3). Bifenthrin, deltamethrin and permethrin were linked to local sources, while cypermethrin, fenvalerate and phenothrin had more prominent regional contributions. In broad terms, most pyrethroids showed no clear seasonal trend. The concentrations and hazard quotients (HQs) showed the following order of occurrence and magnitude: urban > urban-industrial > background areas. HQs increased with decreasing age group, but deterministic and probabilistic estimates did not identify direct health risks for any group. Nevertheless, since only inhalation exposure was considered in this work, other pathways should be investigated to provide a more comprehensive risk assessment of the human exposure to pyrethroids.

Testicular deficiency associated with exposure to cypermethrin, imidacloprid, and chlorpyrifos in adult rats

The testicular deficiency associated with exposure to three widely used insecticides in Egyptian agriculture was evaluated. Animals were orally treated with sub-lethal dose (1/50 of the oral LD50) of cypermethrin (CYP), imidacloprid (IMC), and chlorpyrifos (CPF) at 5, 9 and 1.9 mg/kg/day, respectively, five times a week for one month. The CYP, IMC, and CPF exposure resulted in a significant decline in animal body weight, sperm count, motility, normality, and viability with increased head and tail deformities. Significant reduction in serum testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), testis superoxide dismutase (SOD), and reduced glutathione (GSH) levels. In contrast, catalase (CAT), lipid peroxidation (LPO), and protein carbonyl content (PCC) levels were significantly stimulated. Jointly, obtained results were confirmed by microscopic examination of testis sections. The present data concluded that the CYP, IMC, and CPF have a public health impact and violently interferes with male rat reproductive system.

Multimodal electrochemical and SERS platform for chlorfenapyr detection

Multimodal sensors combining different detection methodologieson a single platform can provide complementary information for the detection of analytes. Here we developed a novel inexpensive metallic substrate that can be used for dual functional sensing via ElectroChemistry (EC)and Surface Enhanced Raman Spectroscopy (SERS). We demonstrated the utility of this platform for the detection of chlorfenapyr, which is an agricultural insecticide anda toxin that disrupts respiratory pathways and proton gradients in mitochondria. Our platform is based on a commercial bimetallic glucosetest strip modified with silver nanoparticles. The performance of EC and SERS was evaluated via test probes potassium ferricyanide ((K3Fe(CN)6)) and 4-Aminothiophenol, respectively. The substratewas used as a working electrode for chlorfenapyr detection via ECand SERS. SERS allows the identification of chlorfenapyr by its characteristic peak near 2230 cm−1, with a Limit of Detection (LOD) of 7 ppm. EC allows for quantitative measurement of the analytewithin the concentration range of 20–50 ppm. The EC LODof 4.2 ppmmeets residue tolerance limit inchive, according to the US Code of Federal Regulations. Thisplatform may open up avenues towards cost-effective and portable detection of other analytes.

Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya

BackgroundMalaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya.MethodsThe study was carried out in 2018–2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area.ResultsAnopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8–84% to 83.3–78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1–16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection.ConclusionAnopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides.Graphic abstract

Short-term metabolic resistance inductive effect of different agrochemical groups on Anopheles gambiae mosquitoes

Background: In order to assess the impact of the different groups of agricultural pesticides used in Côte d'Ivoire on the increase of mosquitoes resistance to insecticides, the expression profiles of 7 P450 cytochromes and one GSTE2 of Anopheles gambiae involved in mosquito resistance to insecticides were studied. The goal of this study was to determine the effect of short exposure of mosquito larvae to different groups of agricultural pesticides on mosquito resistance. Methods: Three groups of pesticides were selected: (i) agricultural insecticide solutions, (ii) none-insecticide pesticide solutions (a mixture of herbicides and fungicides), and (iii) a mixture of the first two. A fourth non-pesticide solution was used as a control. Four groups of each stage 2 larvae (strain Kisumu, male and female) were exposed to 20% concentrated solution for 24 hours. Susceptibility tests for dichlorodiphenyltrichloroethane (DDT) and Deltamethrin were carried out on adults aged 2-5 days. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was performed to quantify the expression of eight metabolic genes involved in mosquito resistance to insecticides. Results: Susceptibility to DDT showed a similar increase in the time required to knock down 50% of mosquitoes (kdt50) in l colonies exposed to insecticides and none-insecticides compared to the control colony. As for deltamethrin, kdt50 was higher in the colonies exposed to insecticides and the pesticide mixture compared to the colony exposed to none-insecticides. Of all the genes studied in all colonies, except for CYP6P1 induced only in the colony consisting of the pesticide mixture, no genes were induced. Conclusions: This study confirmed that induction is influenced by the duration, the concentration of the solution and the type of xenobiotic used as an inducer. The overexpression of CYP6P1 confirmed the inductive effect that a short exposure of mosquito larvae to agricultural pesticides could have.

English

BACKGROUND Due to the widespread use and availability of agricultural insecticides, acute organophosphate poisoning is becoming the most common type of poisoning in Kerala. The cause of death is thought to be a confluence of increased bronchial secretion, bronchospasm, respiratory muscle dysfunction, respiratory center depression and respiratory failure. The purpose of the study is to find the proportion of respiratory failure in patients with organophosphate poisoning. METHODS It is a cross sectional study done in 119 consenting patients who are known cases of organophosphorous (OP) poisoning satisfying the inclusion criteria. They underwent clinical assessment and laboratory investigations to assess complications of organophosphorous poisoning. Clinical features and lab findings were recorded as per protocol. RESULTS 65 out of 119 (54.6 %) had evidence of respiratory failure. Among these 65, 20 % succumbed to death (13). 56.5 % of males (48) and 50 % of females (17) developed respiratory failure. 72.2 % of patients more than 60 years (13) had respiratory failure. Majority of the cases were of chlorpyriphos poisoning 42 (35.3 %). 76.5 % (13) of dimethoate poisoning developed respiratory failure. 93.4 % (57) of patients with respiratory failure had elevated serum amylase levels. CONCLUSIONS Respiratory failure is a very common complication found in organophosphate poisoning. It is more common in males than females and its proportion increases with age. The incidence of respiratory failure is more with dimethoate. Serum amylase levels can be used as a marker for development of respiratory failure in organophosphate poisoning. KEYWORDS Organophosphate Poisoning, Respiratory Failure, Serum Amylase Levels

Impaired neuromuscular function by conjoint actions of organophosphorus insecticide metabolites omethoate and cyclohexanol with implications for treatment of respiratory failure

Background Ingestion of agricultural organophosphorus insecticides is a significant cause of death in rural Asia. Patients often show acute respiratory failure and/or delayed, unexplained signs of neuromuscular paralysis, sometimes diagnosed as “Intermediate Syndrome”. We tested the hypothesis that omethoate and cyclohexanol, circulating metabolites of one agricultural formulation, cause muscle weakness and paralysis. Methods Acetylcholinesterase activity of insecticide components and metabolites was measured using purified enzyme from eel electroplaque or muscle homogenates. Mechanomyographic recording of pelvic limb responses to nerve stimulation was made in anaesthetized pigs and isometric force was recorded from isolated nerve-muscle preparations from mice. Omethoate and cyclohexanol were administered intravenously or added to physiological saline bathing isolated muscle. We also assessed the effect of MgSO4 and cooling on neuromuscular function. Results Omethoate caused tetanic fade in pig muscles and long-lasting contractions of the motor innervation zone in mouse muscle. Both effects were mitigated, either by i.v. administration of MgSO4 in vivo or by adding 5 mM Mg2+ to the medium bathing isolated preparations. Combination of omethoate and cyclohexanol initially potentiated muscle contractions but then rapidly blocked them. Cyclohexanol alone caused fade and block of muscle contractions in pigs and in isolated preparations. Similar effects were observed ex vivo with cyclohexanone and xylene. Cyclohexanol-induced neuromuscular block was temperature-sensitive and rapidly reversible. Conclusions The data indicate a crucial role for organophosphorus and solvent metabolites in muscle weakness following ingestion of agricultural OP insecticide formulations. The metabolites omethoate and cyclohexanol acted conjointly to impair neuromuscular function but their effects were mitigated by elevating extracellular Mg2+ and decreasing core temperature, respectively. Clinical studies of MgSO4 therapy and targeted temperature management in insecticide-poisoned patients are required to determine whether they may be effective adjuncts to treatment.

Role of Endocrine-Disrupting Chemicals in the Pathogenesis of Non-Alcoholic Fatty Liver Disease: A Comprehensive Review.

Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder, affecting around 25% of the population worldwide. It is a complex disease spectrum, closely linked with other conditions such as obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome, which may increase liver-related mortality. In light of this, numerous efforts have been carried out in recent years in order to clarify its pathogenesis and create new prevention strategies. Currently, the essential role of environmental pollutants in NAFLD development is recognized. Particularly, endocrine-disrupting chemicals (EDCs) have a notable influence. EDCs can be classified as natural (phytoestrogens, genistein, and coumestrol) or synthetic, and the latter ones can be further subdivided into industrial (dioxins, polychlorinated biphenyls, and alkylphenols), agricultural (pesticides, insecticides, herbicides, and fungicides), residential (phthalates, polybrominated biphenyls, and bisphenol A), and pharmaceutical (parabens). Several experimental models have proposed a mechanism involving this group of substances with the disruption of hepatic metabolism, which promotes NAFLD. These include an imbalance between lipid influx/efflux in the liver, mitochondrial dysfunction, liver inflammation, and epigenetic reprogramming. It can be concluded that exposure to EDCs might play a crucial role in NAFLD initiation and evolution. However, further investigations supporting these effects in humans are required.

Managing orchard groundcover to reduce pollinator foraging post-bloom.

Agricultural insecticides are believed to play a role in global pollinator decline. In mass-flowering orchard crops, recommendations to reduce exposure of pollinators to insecticides include spraying at periods when bees aren't foraging, such as dusk and dawn and outside of crop flowering times. However, the presence of flowering weeds within orchards mean pollinators may still be found foraging throughout the growing season, increasing the likelihood that exposure will still occur. We hypothesized that removing these weeds within orchard groundcover may reduce pollinator foraging post-bloom and thus reduce exposure of this group to pesticides. We tested this hypothesis by using herbicide to remove flowering broadleaf weeds in the sod middles ('groundcover') between rows of a nectarine orchard in New Jersey, USA, and assessing the effect on pollinator visitation via three different methods. Significantly lower abundance, richness, diversity, and evenness of pollinators were found in plots where herbicide treatment had removed the majority of flowering weeds, compared to untreated plots. This was the case for bees, and for pollinators overall, and was reflected in both visual observations and active sampling through sweep netting. Passive sampling with blue vane traps failed to detect a difference between treatments. Groundcover management in orchards is often employed as part of integrated pest management programs to remove alternative host plants of insect pests. The findings of this study show that it is also effective in reducing post-bloom pollinator foraging in orchards, thus potentially preventing exposure of these beneficial organisms to harmful insecticides. © 2021 Society of Chemical Industry.

English

Fipronil is an N-phenylpyrazole insecticide, a second-generation insecticide which is relatively new and now commonly used in cotton growing community of rural Central India. Farmer suicide and deliberate self-poisoning is menace to the Vidarbha region of rural Central India. There is paucity of research published on fipronil poisoning, clinical features, complications and treatment data. It is scarcely documented worldwide. Agricultural insecticides are common household items in rural areas of developing countries. Because of their easy availability, insecticides became a major source of deliberate self-poisoning. As per World Health Organization (WHO), around 3 million poisoning cases with around 0.2 million deaths are noted annually in the world. 1 About 99 % of these deaths occur in developing countries. Insecticide poisoning is an important public issue in India.Around 168,000 deaths occurred from pesticide self-poisoning which totals to almost 19.7 % of the global suicides.2 The most common cause of self-poisoning in Central India is ingestion of organophosphorus compounds (OPC). Poisoning with organophosphorus compound insecticides has high mortality rate.1 In the last 20 years, there is development of a new class of insecticides in view of mortality due to accidental exposures of organophosphorus and organochlorine compounds. Fipronil being one of these chemicals, is considered less harmful to humans. According to WHO classification fipronil is class II moderately hazardous pesticide.3 Fipronil, an N-phenylpyrazole with a trifluoromethyl sulfinyl substituent, one of the first second generation insecticides, acts at the γ-aminobutyric acid (GABA) receptor and blocks the chloride channel. Fipronil is often used to control pests, fleas and ticks on pets. There is, however, very less evidence or research on human beings on their toxicity; thus, post marketing surveillance is important to detect any undesirable health issues associated with these chemicals. Until now only 3 case reports are published regarding fipronil poisoning, two cases form India and others from Sri Lanka. Hence, we are reporting a case of acute fipronil poisoning which presented as acute gastritis and sinus bradycardia.

Biodegradation of Lindane (γ-Hexachlorocyclohexane) To Nontoxic End Products by Sequential Treatment with Three Mixed Anaerobic Microbial Cultures.

The γ isomer of hexachlorocyclohexane (HCH), also known as lindane, is a carcinogenic persistent organic pollutant. Lindane was used worldwide as an agricultural insecticide. Legacy soil and groundwater contamination with lindane and other HCH isomers is still a big concern. The biotic reductive dechlorination of HCH to nondesirable and toxic lower chlorinated compounds such as monochlorobenzene (MCB) and benzene, among others, has been broadly documented. Here, we demonstrate that complete biodegradation of lindane to nontoxic end products is attainable using a sequential treatment approach with three mixed anaerobic microbial cultures referred to as culture I, II, and III. Biaugmentation with culture I achieved dechlorination of lindane to MCB and benzene. Culture II was able to dechlorinate MCB to benzene, and finally, culture III carried out methanogenic benzene degradation. Distinct Dehalobacter populations, corresponding to different 16S rRNA amplicon sequence variants in culture I and culture II, were responsible for lindane and MCB dechlorination, respectively. This study continues to highlight key roles of Dehalobacter as chlorobenzene- and HCH -respiring bacteria and demonstrates that sequential treatment with specialized anaerobic cultures may be explored at field sites in order to address legacy soil and groundwater contamination with HCH.

Thiamethoxam Exposure Induces Endoplasmic Reticulum Stress and Affects Ovarian Function and Oocyte Development in Mice

Neonicotinoids are the most widely used insecticides in modern agriculture, and their residues have been found in the environment and food. Previous studies reported that neonicotinoids exert toxic effects in various tissues, but whether they interfered with the female reproductive process remains unknown. In our present research, thiamethoxam was selected as a representative neonicotinoid to establish a mouse toxicity model with gavage. We found that thiamethoxam decreased the ovarian coefficient and disrupted the expression of female hormone receptors, subsequently affecting follicle development. Ovarian granulosa cells from the thiamethoxam exposure group underwent a high level of apoptosis. Using transcriptome analysis, we showed that thiamethoxam exposure altered the expression of multiple oocyte genes related to inflammation, apoptosis, and endoplasmic reticulum stress. Thiamethoxam also adversely affected oocyte and embryo development. Western blotting and fluorescence staining results confirmed that thiamethoxam affected the integrity of DNA, triggered apoptosis, promoted oxidative stress and endoplasmic reticulum stress, and impaired mitochondrial function. Collectively, our results indicated that thiamethoxam exposure disrupts ovarian homeostasis and decreases oocyte quality via endoplasmic reticulum stress and apoptosis induction.

Overview of Domestic and Agricultural Pesticides Use Contributing to Aedes aegypti Resistence in Ambarawa Subdistrict, Indonesia

Ambarawa Sub District Semarang District is an endemic area of DHF. Furthermore, the year 2019 recorded an increase in the IR and CFR by 271.73, and 1.123% respectively. Insecticide resistance contributed to the increase in DHF cases. Therefore, this study aims to determine the description of community behavior concerning the use of household and agricultural insecticide which lead to insecticide resistance in Aedes aegypti. This type of research is descriptive using qualitative methods. The informants are insecticide users in Ambarawa subdistrict. Twenty-four sample is choosen by purposive sampling. In-depth interview is carried out for the data collection. Data analysis used is data reduction, data presentation, and data verification using the manual way. As the result of the study, most of the subjects experienced a decrease in the effectiveness of insecticides, caused by poor community knowledge, and behavior of people who did not apply any insecticide resistance management guidelines. Considering the condition of current insecticide circulation, the government needs to make policies relating to the management of insecticide resistance

Ecotoxicity of imidacloprid to soil invertebrates in two tropical soils with contrasting texture.

Imidacloprid is one of the most commercialized insecticides in agriculture in the world, with a broad spectrum of action. However, little is known about the effects of commercial formulations containing this active ingredient (a.i.) on non-target organisms in tropical soils. Our objective was to assess the toxicity based on the predicted environmental concentration (PEC) of imidacloprid, in the avoidance behaviour of earthworms and collembolans as well as in the reproduction of collembolans, in two representative soils of the Brazilian Cerrado with contrasting texture (clayey Oxisol and sandy Entisol). Ecotoxicity tests were carried out according to ISO protocols to assess the avoidance behaviour of earthworms (Eisenia andrei) and avoidance and reproduction of collembolans (Folsomia candida). In the earthworm's avoidance test, more than 80% of the individuals were found in the control, in all tested concentrations, indicating a possible habitat function loss in both soils. The avoidance behaviour of collembolans was observed in both soils, being more expressive (up to 75% of escape) in Oxisol. In Entisol, only the two highest concentrations were avoided (up to 63%). There was a negative effect on the reproduction of collembolans in both soils, with a higher EC50 value (0.255 mg kg-1) in Oxisol than in Entisol (0.177 mg kg-1), demonstrating higher toxicity in the sandy soil. These differences were attributed to the contrasting texture of the studied soils, probably due to lower retention of the a.i. in the sandy soil, causing an increased bioavailability. This study demonstrated that imidacloprid can be highly toxic to soil invertebrates, even in soil concentrations lower than those expected from recommended dose, causing an impact on the edaphic organisms and, consequently, compromising its functions in the soil ecosystem.

In vitro cytotoxic, genotoxic, and antityrosinase activities of Clitoria macrophylla root.

Clitoria macrophylla Wall. (Leguminosae), locally known as Non-tai-yak or An-chan-pa, commonly distributed in tropical nations and Southeast Asia. Regarding traditional Thai medical system, C. macrophylla roots carry out a potential in dermatology. Its roots are also used as insecticide in agriculture and animal farming. Moreover, clitoriacetal is the major component that can be detected in C. macrophylla root. This research aimed to assess the efficacy of C. macrophylla root extract and clitoriacetal for its anticancer and antityrosinase activities as well as to assess in vitro safety potential for its cytotoxic and genotoxic effects. C. macrophylla root and clitoriacetal were tested by brine shrimp lethality, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, comet assay, and antityrosinase activity. C. macrophylla root, clitoriacetal, and rotenone demonstrated the toxicity against brine shrimp nauplii with LC50 of 332.15, 136.54, and 0.15 μg/mL, respectively. C. macrophylla root and clitoriacetal showed cytotoxic potential against breast ductal carcinoma (BT-474), liver hepatoblastoma (Hep-G2), and colon adenocarcinoma (SW-620). At 100 μg/mL, the percent DNA damage of C. macrophylla root and clitoriacetal was 37.84% and 36.01%, respectively. C. macrophylla root and clitoriacetal were able to inhibit the tyrosinase enzyme with IC50 of 12.27 and 7.30 mg/mL, respectively, which less effective than glutathione (positive control). The present study revealed the in vitro biological activities of C. macrophylla root and its clitoriacetal constituent which proposed the scientific evidences in efficacy and safety evaluation including in vitro cytotoxicity, DNA damage as well as antityrosinase activities.

Toxico-Pathological Studies of the Insecticide Metasystox-R (Oxydemeton-Methyl) in Rabbits

One of the widely used insecticides in agriculture and urban pest control is oxydemeton-methyl, which is an organothiophosphate compound. It has a high bioaccumulation effect due to its increased solubility and mobility. This study was carried out to investigate the effect of oxydemeton-methyl toxicity on the environment, and female New Zealand rabbits were used as a model. The rabbits were given oxydemeton-methyl orally in drinking water at a concentration of 34 ppm for six weeks. The clinical signs were diarrhoea, emesis, salivation, lacrimation, fasciculation, muscle tremors and weakness. The haematological parameters, such as the RBCs count, the Hb concentration and the PCV % were significantly decreased. On the contrary, the WBCs count were significantly increased. In addition, an acetylcholinesterase enzyme was inhibited, and a histopathological examination on the liver showed small areas of oval and bridge necrosis infiltrated with mononuclear cells. In the kidneys, there was a variable degree of nephrosis, and the heart showed foci of myocardial degeneration infiltrated with mononuclear cells. Therefore, it is concluded that oxydemeton-methyl is highly toxic to the environment.

МЕТОДИЧЕСКИЕ ПОДХОДЫ К ОЦЕНКЕ ЭНТОМОПАТОГЕННОЙ АКТИВНОСТИ МИКРООРГАНИЗМОВ В ОТНОШЕНИИ НАСЕКОМЫХ-ВРЕДИТЕЛЕЙ IN VITRO (ОБЗОР)

Excessive application of chemical insecticides in agriculture has led to some serious problems that threaten the environment and human health. One of the possible ways to overcome the situation is to shift to environmentally-friendly preparations based on entomopathogenic bioagents. The purpose of this review was to search for and systematize methodological approaches to determine the entomopathogenic activity of microorganisms of various taxonomic groups in laboratory conditions. The expediency of choosing the necessary method when studying a particular phenomenon or process is an important point both in the fundamental and applied field of research. The primary assessment of the entomopathogenic activity of microorganisms in vitro is the basis for expanding the spectrum of their action, introducing new strains into collections. It also contributes to the replenishment of knowledge about the already known properties of various types of microorganisms. All this, certainly, is connected with the further choice of them as biological agents. Each of the presented groups of entomopathogens has its distinctive features of the mechanisms of action determined by the target insect. Concerning the choice of methodological approaches for assessing the entomopathogenic effect of fungi, the authors relied on the physiological characteristics of the insect and its stage of harmfulness. The researchers were guided by methodological approaches of oral infection of insects using an infected food source to study the activity of bacterial strains. Pathological changes in the cellular structure, as well as deformations of intestinal elements, were noted. The most common way to assess the effect of entomopathogenic viruses in the laboratory is the method of surface infection of the food source of the tested insect, taking into account the high specialization of the agent. When studying the mechanisms of action of fungal, bacterial and viral agents, researchers injected a suspension of the pathogen into the insect’s body. The search and systematization of relevant methodological approaches to assess entomopathogenic microorganisms depending on the taxonomic affiliation is an important part of the work directly related to the development of a high-quality and effective bioinsecticide.