The impact of lethal and sub-lethal exposure of emamectin benzoate on population of Spodoptera litura (Lepidoptera: Noctuidae) under laboratory conditions.

Emamectin benzoate is an avermectin bio-insecticide commonly used for managing several insect pests including Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), a major polyphagous pest of many cultivated crops. The current study was conducted to evaluate the effects of emamectin benzoate on the fitness of S. litura populations exhibiting differential susceptibility to insecticide. The selection process and all the bioassays were carried out using 6-day-old 2nd instar larvae of S. litura. A field-collected population of S. litura was divided into two groups: one selected with emamectin benzoate for eight generations (EB-Sel) and the other kept unexposed (Unsel-Lab) to insecticide in the laboratory. An increase in resistance ratio from 1.71-fold in the F1 generation to 22.54-fold in the F8 generation of the EB-Sel population was observed compared to the Unsel-Lab (F8) population. The EB-Sel and Unsel-Lab populations were treated with their respective lethal and sub-lethal concentrations which resulted in an extended development period, decreased larval survival, and adult emergence along with increased morphological abnormalities in adults. Significant reductions were observed in both male and female longevity, fecundity, egg hatching, net reproductive rate (R0), intrinsic rate of increase (rm), and finite rate of increase (λ) in EB-Sel and Unsel-Lab populations. Higher concentrations of the insecticide also reduced the relative fitness (Rf) of S. litura larvae, with maximum effect at LC50 of the EB-Sel population where the Rf value was 0.32 compared to the Unsel-Lab population. Both populations have been affected by emamectin benzoate exposure, however, the impact was more pronounced in the EB-Sel population indicating fitness costs. Our results suggested the fitness cost linked to emamectin benzoate resistance in S. litura which might favor managing insecticide resistance by reducing the frequency of resistant alleles by removing selection pressure. Consequently, our research provides significant insights to devise better pest management strategies for S. litura.

Field efficacy of insecticides for suppressing white mango scale insect (Aulacaspis tubercularis Newstead) (Hemiptera: Diaspididae) in southwest Ethiopia.

White mango scale (WMS) Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) is a polyphagous armored scale insect which is considered one of the key pests of mango (Mangifera indica L.) around the world. Mango is widely grown in Ethiopia whereas its production is challenged by WMS in the last decade. Effective formulations that could help manage the scale as part of IPM practice were sought from field experiments at Seka mango farm, Ethiopia in 2019 and 2020 seasons. The study aimed to evaluate the efficacy of some formulations against WMS on mango trees. Randomized complete block designs with three replications were used for the experiments and each tree served as a plot. Allocation of each treatment within each replication was done randomly. The treatments were applied sequentially three times at 14 days interval using motorized Knapsack sprayer coinciding with peak period of natural infestation. Scale numbers before and after each spray were counted using a microscope with LCD. Sum of live crawler, female and male was registered as WMS count data. Results showed that dimethoate, diazinon, imidacloprid & λ-cyhalothrin sprayed alone; dimethoate rotated with imidacloprid & λ-cyhalothrin, chlorpyrifos-ethyl rotated with paraffin, and diazinon rotated with azadirachtin, caused total mortality of the scales. The results also showed that, chlorpyrifos-ethyl, deltamethrin, paraffin oil and λ-cyhalothrin sprayed alone caused percent reduction with range 83-95 % in both seasons. Hence, the study revealed that dimethoate, diazinon, imidacloprid & λ-cyhalothrin applied individually, dimethoate rotated with imidacloprid & λ-cyhalothrin, chlorpyrifos-ethyl rotated with paraffin and diazinon rotated with azadirachtin fully protect mango trees from WMS and significantly superior to other treatments. Therefore, chemical control of A. tubercularis may consider the use of these materials as foliar application and can be used as components for integrated pest management plans for WMS. However, application in the form of rotation is preferred to the alone spray as the former could substantially reduce the likelihood of inducing pesticide resistance. Cost implications and effects of the products on the natural enemy and residual toxicity in fruits need to be studied.

Knocking Out of UDP-Glycosyltransferase Gene UGT2B10 via CRISPR/Cas9 in Helicoverpa armigera Reveals Its Function in Detoxification of Insecticides.

The role of insect UDP-glycosyltransferases (UGTs) in the detoxification of insecticides has rarely been reported. A UGT gene UGT2B10 was previously found overexpressed in a fenvalerate-resistant strain of Helicoverpa armigera. Herein, UGT2B10 was cloned, and its involvement in insecticide detoxification was investigated. UGT2B10 was highly expressed in the larvae, mainly in the fat body and midgut. Treatment with UGT inhibitors 5-nitrouracil and sulfinpyrazone significantly enhanced the fenvalerate toxicity. Knocking down UGT2B10 by RNAi significantly increased the larvae mortality by 17.89%. UGT2B10 was further knocked out by CRISPR/Cas9, and a homozygous strain (HD-dUGT2B10) with a C-base deletion at exon 2 was obtained. The sensitivity of HD-dUGT2B10 to fenvalerate, deltamethrin, cyantraniliprole, acetamiprid, and lufenuron increased significantly, with sensitivity index increased 2.523-, 2.544-, 2.250-, 2.473-, and 3.556-fold, respectively. These results suggested that UGT2B10 was involved in the detoxification of H. armigera to insecticides mentioned above, shedding light upon further understanding of the detoxification mechanisms of insecticides by insect UGTs.

Pesticide contamination patterns in Montagu's harrier (Circus pygargus) chicks.

Biomonitoring of persistent pesticides in birds of prey has been carried out for decades, but few studies have investigated their relevance for the monitoring of non-persistent pesticides. Herein, we determined the contamination patterns of multiple pesticides in Montagu's harrier (Circus pygargus) chicks in an intensive farming area of southwestern France. Blood samples from 55 chicks belonging to 22 nests in 2021 were assessed for 104 compounds (herbicides, fungicides, insecticides, safeners and synergists). All chicks had at least one herbicide in their blood, and half had at least two compounds. The 28 compounds detected comprised 10 herbicides, 12 fungicides, 5 insecticides and 1 synergist. Mixtures in blood were predominantly composed of herbicides, and six chicks presented a mixture of the three pesticide classes. The most prevalent compounds were sulcotrione (96% of chicks), tebutam (44%) and chloridazon (31%), of which the latter two had been banned in France for 19 and 3 years, respectively, at the time of sampling. Most compounds are considered non-acutely toxic, but sulcotrione is potentially carcinogenic, mutagenic and reprotoxic, raising questions about the effects on the health of nestlings. Biomonitoring of multiple pesticides through Montagu's harrier chicks in agroecosystems is clearly relevant because it reflects the general pattern of agricultural pesticide use in the study area. It also raises questions about exposure pathways in chicks, and further investigations are needed to disentangle the roles of dietary routes and maternal transfer for the established pesticide contamination patterns.

Identification and biophysical characterization of potential phytochemical inhibitors of carboxyl/choline esterase from Helicoverpa armigera for advancing integrated pest management strategies.

In the realm of disease vectors and agricultural pest management, insecticides play a crucial role in preserving global health and ensuring food security. The pervasive use, particularly of organophosphates (OPs), has given rise to a substantial challenge in the form of insecticide resistance. Carboxylesterases emerge as key contributors to OP resistance, owing to their ability to sequester or hydrolyze these chemicals. Consequently, carboxylesterase enzymes become attractive targets for the development of novel insecticides. Inhibiting these enzymes holds the potential to restore the efficacy of OPs against which resistance has developed. This study aimed to screen the FooDB library to identify potent inhibitory compounds targeting carboxylesterase, Ha006a from the agricultural pest Helicoverpa armigera. The ultimate objective is to develop effective interventions for pest control. The compounds with the highest scores underwent evaluation through docking studies and pharmacophore analysis. Among them, four phytochemicals-donepezil, protopine, 3',4',5,7-tetramethoxyflavone, and piperine-demonstrated favorable binding affinity. The Ha006a-ligand complexes were subsequently validated through molecular dynamics simulations. Biochemical analysis, encompassing determination of IC50 values, complemented by analysis of thermostability through Differential Scanning Calorimetry and interaction kinetics through Isothermal Titration Calorimetry was conducted. This study comprehensively characterizes Ha006a-ligand complexes through bioinformatics, biochemical, and biophysical methods. This investigation highlights 3',4',5,7-tetramethoxyflavone as the most effective inhibitor, suggesting its potential for synergistic testing with OPs. Consequently, these inhibitors offer a promising solution to OP resistance and address environmental concerns associated with excessive insecticide usage, enabling a significant reduction in their overuse.

A clinical warning in the treatment of chlorfenapyr poisoning.

Chlorfenapyr, an arylpyrrole-based insecticide, disrupts mitochondrial oxidative phosphorylation to deprive the target organism of energy. Chlorfenapyr poisoning in humans causes distinct clinical signs such as hyperhidrosis, malignant hyperthermia, rhabdomyolysis, and delayed neurological symptoms that worsen over time and can be fatal. When treating acute chlorfenapyr poisoning, physicians must consider the latent period and not assume that a patient is safe after an initial response to treatment. It is important to take measures before sudden, fatal symptoms appear. This paper presents three cases of chlorfenapyr poisoning as a warning for physicians to understand its clinical course and treatment.

Modulation of the antioxidant system by glycoalkaloids in the beetle Tenebrio molitor L.

Various factors may affect the antioxidative system in insects, including xenobiotics. Glycoalkaloids (GAs) are plant secondary metabolites produced mainly by the Solanaceae family (nightshades), such as the food crop tomato Solanum lycopersicum L. These compounds exhibit a wide range of biological activities and have attracted increasing interest in the context of potential insecticide properties. Therefore, the aim of the presented study was to analyze the effects of GAs (solanine, chaconine, tomatine, and extracts of tomato leaves) on lipid peroxidation; the expression levels of genes encoding manganese superoxide dismutase (MnSOD), catalase (CAT), and heat shock protein 70 (HSP70); and the enzymatic activity of SOD and CAT in Tenebrio molitor larvae. This species is amodel organism for toxicological and ecophysiological studies and is also a pest of grain storage. The reported changes depend on the GA concentration, incubation time, and type of insect tissue. We observed that the tested GAs affected MnSOD expression levels, increased SOD activity in the fat body, and reduced enzyme activity in the gut. The results showed that CAT expression was upregulated in the fat body and that the enzymatic activity of CAT in the gut was greater in the treated group than in the control group. Moreover, GAs affected HSP70 expression and malondialdehyde levels in both tested tissues. This research contributes to our knowledge about the effects of GAs on the antioxidative system of T. molitor beetles. As efficient antioxidative system functioning is necessary for survival, the tested components may be targets of potential bioinsecticides.

Phytochemical Investigations, Antioxidant and Insecticidal Properties of Essential Oil and Extracts from the Aerial Parts of Pelargonium graveolens from Morocco.

The essential oil and the aqueous and ethanolic extracts obtained from the aerial parts of Pelargonium graveolens cultivated in Morocco were studied for their antioxidant and insecticidal activity against rice weevils (Sitophylus oryzae). The total phenolic content of the extracts was determined by a spectrophotometric method and the phenolic compounds were extensively characterized by HPLC-PDA/ESI-MS. To evaluate antioxidant potential, three in vitro assays were used. In the DPPH test, the ethanolic extract was the most active, followed by the aqueous extract and the essential oil. In the reducing power assay, excellent activity was highlighted for both extracts, while in the Fe2+ chelating activity assay, weak activity was observed for both the essential oil and the ethanolic extract and no activity for the aqueous extract. Concerning insecticide activity, the toxicity of the essential oil and the extracts was tested against rice weevils; the lethal concentrations LC50 and LC99 were determined, as well as the lethal time required for the death of 50% (LT50) and 99% (LT99) of the weevils. The essential oil had the highest activity; 100% mortality of S. oryzae was observed around 5, 9, and 8 days for the essential oil and the aqueous and ethanolic extracts, respectively.

Preparation and insecticidal performance of 1,8-cineole/cellulose acetate electrospun fibrous membranes.

Plant essential oils and their components have broad application prospects as substitutes for chemical pesticides. However, the burst release and persistence time need to be optimized. In this study, 1,8-cineole (1,8-CIN) was embedded in degradable cellulose acetate (CA) by electrospinning to achieve sustained release. The results showed that the sustained-release membrane had good morphology and thermal stability. The release test showed that the deficiency of the explosive release of 1,8-CIN improved after encapsulation, and 21.74 % of the drug remained after 42 days. In the application test, the fiber membrane could kill the test insects in a short period of time and affect the behavior choices of the test insects. It affected the growth and oviposition of the test insects and reduced adult longevity by 13.64 % and oviposition by 23.35 %. This study can improve the utilization rate of pesticides, alleviate environmental pressure, and provide new ideas for pest control.

Efficacy of plant-based products and nonconventional pesticides for the management of tropical bed bug.

Insecticide resistance is widespread in global bed bug populations. Both common bed bugs and tropical bed bugs are pyrethroid-resistant among most field populations. Plant-based products and nonconventional pesticides offer minimal-risk strategies for managing bed bug resistance, but this strategy has yet to be formally evaluated in Cimex hemipterus (F.) (Hemiptera: Cimicidae). Here, several commercial plant-based formulations (Cedarcide, EcoRaider (also known as EcoVenger), EcoSMART, and Bio-D), a novel product, Provecta, and a pyrethroid insecticide, Pesguard FG161 were tested against pyrethroid-susceptible and resistant strains of C. hemipterus using direct spray, residual exposure, and egg dipping assays. Direct spray treatments outperform residual applications against all tested bed bug strains. Cedarcide exhibits the highest consistency in eliminating bed bugs, followed by EcoRaider, EcoSMART, and Provecta that outperform Bio-D and Pesguard FG161. In comparison to Pesguard FG161, all plant-based insecticide products and Provecta showed higher efficacy against pyrethroid-resistant strains. Although effective, product efficacy varies in terms of speed. Cedarcide kills all bed bugs within 1 min after spraying; however, other products can take up to 9 days to achieve 100% mortality. The efficacy of all products was reduced when evaluated on fabric surface (42%-65% mortality). Cedarcide and EcoRaider reduced egg hatchability by 37%-73% and 47%-70%, respectively. This study suggests that certain plant-based insecticides and an unconventional insecticide can serve as alternative direct spray treatments for managing tropical bed bugs, though their residual effects are limited.

Chlorfenapyr poisoning: a systematic review.

INTRODUCTION: Chlorfenapyr, a N-substituted halogenated pyrrole, is a broad-spectrum insecticide. The insecticidal activity of chlorfenapyr depends on its biotransformation by hepatic cytochrome P450 monooxygenases to tralopyril, which uncouples mitochondrial oxidative phosphorylation and disrupts adenosine triphosphate production. Neither the metabolism of chlorfenapyr nor the mechanism of tralopyril is completely elucidated. Acute human chlorfenapyr poisoning is not well characterized, and best practice in management following acute exposure is unclear. The purpose of this review is to characterize acute human chlorfenapyr poisoning by its clinical course, laboratory investigations, and imaging findings and propose a management plan for acute human chlorfenapyr exposure. METHODS: We systematically searched PubMed, Web of Science, Google Scholar, and EMBASE from inception to April 2024 across all languages for human chlorfenapyr and tralopyril cases, with descriptions of exposure, clinical manifestations, and clinical course included. Only manuscripts and abstracts from scientific conferences with sufficient clinical data following acute human exposures were included. In vitro studies, animal studies, agricultural studies, environmental impact studies, and non-clinical human studies were excluded. We then reviewed citations of included studies for additional eligible publications. Non-English publications were translated using Google Translate or primarily translated by our authors. The study adhered to Preferred Reporting for Systematic Reviews and Meta-analyses (PRISMA) guidelines for systematic reviews. RESULTS: We identified 3,376 publications of which 48 met study inclusion criteria, describing 75 unique cases of human poisoning from ingestion, inhalation, dermal exposure, and intra-abdominal injection of chlorfenapyr. No cases of tralopyril exposure were identified. The median time from exposure to symptom onset was six hours (interquartile range 1-48 hours). The most frequent initial or presenting signs/symptoms included diaphoresis, nausea and/or vomiting, and altered mental status. While hyperthermia (≥38 degrees centigrade) was less common at presentation, hyperthermia developed in 61 percent of all patients and was temporally associated with clinical deterioration and death. Most common laboratory abnormalities included elevated blood creatine kinase activity, hepatic aminotransferase activities, and lactate concentration. Imaging studies of the central nervous system often showed extensive symmetrical white matter abnormalities with swelling. Case fatality was 76 percent, and survivors commonly experienced sustained neurological sequelae. Management strategies were highly varied, and the effectiveness of specific medical interventions was unclear. DISCUSSION: Acute human chlorfenapyr poisoning is characterized by a latent period as long as 14 days, deterioration over hours to days, and can result in serious morbidity and mortality. Development of hyperthermia, likely driven by oxidative phosphorylation uncoupling by tralopyril, is an ominous clinical sign and is temporally associated with clinical decompensation and death. Laboratory abnormalities, particularly elevated creatine kinase activity, hepatic aminotransferase activities, and lactate concentration, were common, but only creatine kinase activity differed amongst survivors and fatalities. Best clinical practice in the management of patients exposed to chlorfenapyr is unclear, and we opine that a conservative approach with close clinical monitoring and supportive care is prudent. LIMITATIONS: The limitations of all reviews include their inherent retrospective and observational nature as well as publication bias that emphasizes severe outcomes, thus impacting the spectrum of illness and skewing mortality percentage. In addition, we interrogated a finite number of databases for publications on human chlorfenapyr exposure and there were limited cases with laboratory testing to confirm chlorfenapyr poisoning. Analysis of our systematic review was not powered to detect differences between groups, comparative statistics were not performed, and significance is not reported. CONCLUSIONS: Acute human chlorfenapyr toxicity is characterized by a latent period following exposure, development of new or progression of established signs/symptoms, potential for critical illness, rapid deterioration, serious morbidity, and mortality. A conservative approach to patient management is prudent.

Morinda citrifolia Essential Oil: A Plant Resistance Biostimulant and a Sustainable Alternative for Controlling Phytopathogens and Insect Pests.

With the growing demand for sustainable and safe agricultural practices, plant compounds emerge as a solution for biological activities. Here, we evaluated the potential of using Morinda citrifolia essential oil to induce plant resistance and to control phytopathogens (Curvularia lunata) and insect pests (Daubulus maidis). We conducted a chromatographic analysis to unveil the essential oil components. We also quantified the activity levels of antioxidant enzymes and chitinase for resistance induction. The antifungal action was evaluated through disease progression and the inhibition of mycelial growth in addition to in silico studies that made it possible to predict the interaction site between the fungal protein and the compounds. We assessed the toxicity and repellent actions towards the D. maidis. Octanoic acid (58.43%) was identified as the essential oil major compound. Preventive treatment with essential oil and octanoic acid (25.0 µL mL-1) increased not only the plant defense activities (i.e., the activity of the enzymes superoxide dismutase, catalase, phenol peroxidase, ascorbate peroxidase, and chitinase) but also controlled Curvularia leaf spot. The stable interactions between octanoic acid and tyrosine-tRNA ligase from C. lunata suggested protein synthesis inactivation. The essential oil inhibited 51.6% of mycelial growth, and this effect was increased to 75.9% with the addition of adjuvants (i.e., angico gum). The essential oil reduced 76% of the population of D. maidis adults and repelled 50% of the number of D. maidis after 48 h under field conditions. The repellency effect in the field reduced the population of D. maidis adults, transmitters of the stunting complex, by 50%. The results highlight the potential of M. citrifolia as a resistance activator, fungicide, insecticide, and an effective biorational alternative.

Peer review of the pesticide risk assessment of the active substance paraffin oil (CAS 8042-47-5, chain lengths C17-C31).

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Greece, and co-rapporteur Member State, France, for the pesticide active substance paraffin oil are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of paraffin oil as an acaricide and insecticide on potatoes, ornamentals (flower bulbs) and orchards (pear/apple), on pome fruit and stone fruit, on field and permanent protected fruiting vegetables and on field and permanent protected roses and on citrus. The reliable end points appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Occupational exposure to malaria, leishmaniasis and arbovirus vectors in endemic regions: A systematic review.

Vector-borne diseases, including dengue, leishmaniasis and malaria, may be more common among individuals whose occupations or behaviours bring them into frequent contact with these disease vectors outside of their homes. A systematic review was conducted to ascertain at-risk occupations and situations that put individuals at increased risk of exposure to these disease vectors in endemic regions and identify the most suitable interventions for each exposure. The review was conducted in accordance with PRISMA guidelines on articles published between 1945 and October 2021, searched in 16 online databases. The primary outcome was incidence or prevalence of dengue, leishmaniasis or malaria. The review excluded ecological and qualitative studies, abstracts only, letters, commentaries, reviews, and studies of laboratory-acquired infections. Studies were appraised, data extracted, and a descriptive analysis conducted. Bite interventions for each risk group were assessed. A total of 1170 articles were screened and 99 included. Malaria, leishmaniasis and dengue were presented in 47, 41 and 24 articles, respectively; some articles presented multiple conditions. The most represented populations were soldiers, 38% (43 of 112 studies); refugees and travellers, 15% (17) each; migrant workers, 12.5% (14); miners, 9% (10); farmers, 5% (6); rubber tappers and missionaries, 1.8% (2) each; and forest workers, 0.9% (1). Risk of exposure was categorised into round-the-clock or specific times of day/night dependent on occupation. Exposure to these vectors presents a critical and understudied concern for outdoor workers and mobile populations. When devising interventions to provide round-the-clock vector bite protection, two populations are considered. First, mobile populations, characterized by their high mobility, may find potential benefits in insecticide-treated clothing, though more research and optimization are essential. Treated clothing offers personal vector protection and holds promise for economically disadvantaged individuals, especially when enabling them to self-treat their clothing to repel vectors. Secondly, semi-permanent and permanent settlement populations can receive a combination of interventions that offer both personal and community protection, including spatial repellents, suitable for extended stays. Existing research is heavily biased towards tourism and the military, diverting attention and resources from vulnerable populations where these interventions are most required like refugee populations as well as those residing in sub-Saharan Africa.

High nitrogen application in maize enhances insecticide tolerance of the polyphagous herbivore Spodoptera litura by induction of detoxification enzymes and intensification of cuticle.

Nitrogen (N) is one of the most intensively used fertilizers in cropping system and could exert a variety of bottom-up effects on the ecological fitness of herbivores. However, the effects of increased N inputs on insect pesticide tolerance have not been comprehensively understood. Bioassays showed that high N (HN) applied to maize plants significantly increased larval tolerance of Spodoptera litura to multiple insecticides. Activities of detoxification enzymes were significantly higher in the larvae fed on maize plants supplied with HN. RNA-seq analysis showed that numerous GST and cuticle-related genes were induced in the larvae fed on HN maize. RT-qPCR analysis further confirmed four GST genes and larval-specific cuticle gene LCP167. Furthermore, when injected with dsRNA specific to GSTe1, GSTs5, and LCP167, the mortality of larvae treated with methomyl was about 3-fold higher than that of dsGFP-injected larvae. Electron microscope observation showed that cuticle of the larvae fed on HN maize was thicker than the medium level of N. These findings suggest that increased application of N fertilizer enhances insecticide tolerance of lepidopteran pests via induction of detoxification enzymes and intensification of cuticle. Thus, overuse of N fertilizer may increase pest insecticide tolerance and usage of chemical insecticides.

Novel Inhibitor of Glutamate-Cysteine Ligase Catalytic Subunit against Tribolium castaneum: High-Throughout Virtual Screening, Molecular Docking and Dynamics Simulation, and Bioassay.

The enzyme glutamate-cysteine ligase catalytic subunit (Gclc) is a rate-limiting enzyme in the biosynthesis of glutathione that is involved in antioxidant defense, detoxification of xenobiotics, and/or its metabolites and regulates the cell cycle and immune function. Therefore, Gclc presents an appealing target for the development of novel insecticides. In this study, we conducted high-throughput virtual screening from the ZINC20 database and identified three compounds with high binding affinity to the Tribolium castaneum Gclc (TcGclc). Ultimately, we selected ZINC000032992384 due to its superior stability and lowest binding energy, as determined through molecular dynamics simulations. Bioassay results revealed that the IC50 value of ZINC000032992384 was 19.70 µM lower than that of BSO (49.67 µM). Furthermore, the larval mortality in the ZINC000032992384 treated group was 63.8%, significantly higher than that of the controls (29.1% in the dichlorvos group and 6.4% in the acetone group). This study provides novel insights for the development of a Gclc-targeted inhibitor as a potent insecticide based on the interaction between receptors and ligands.

Actividad repelente e insecticida de cuatro aceites esenciales de plantas recolectadas en Chocó-Colombia contra Tribolium castaneum / Repellent and insecticidal activity of four essential oils from plants recolleted in Chocó-Colombia against Tribolium castaneum

This study aimed to determine the repellent and insecticidal activity of four essential oils (EOs) from plants collected in the Chocó rain forest, Colombia, against T. castaneum . Conventional hydrodistillation was used to obtain the EOs. The repellent and insecticidal activities were evaluated by the preference area and gas dispersion methods, espectively. Statistical differences (p<0.05) were determined by applying a student's t-test. EOs of Siparuna guianensis, S. conica, Piper marginatum, and Nectandra acutifolia showed excellent repellent properties as the main findings, highlighting S. conicaEO with 84% repellency (1-hµL/cm2), while P. marginatum showed to be bioactive to the dose of 500 µL/mL (72 h), inducing mortality of 100% of the exposed population. In conclusion, the results evidenced the repellent properties of the EOs evaluated against T. castaneum , which allows us to conclude that these plant species are potential natural sources producing bio-repellents that contribute to the integrated control of T. castaneum.

Se evaluaron cuatro aceites esenciales (AEs) de plantas recolectadas en la selva pluvial del Chocó, Colombia, para determinar su actividad repelente e insecticida contra T. castaneum. Los AEs fueron obtenidos por hidrodestilación convencional. Las actividades repelentes e insecticidas se evaluaron por los métodos de área de preferencia y dispersión de gas, respectivamente. Las diferencias significativas (p<0,05) fueron determinadas aplicando una prueba t de student. Los AEs de Siparuna guianensis, S. conica, Piper marginatum y Nectandra acutifolia mostraron excelentes propiedades repelentes, destacando el AE de S. conicacon un 84% de repelencia (1µL/cm2), mientras que el AE de P. marginatummostró ser bioactivo a la dosis de 500 µL/mL (72 h) al inducir la mortalidad del 100% de la población expuesta. Se concluye que estas especies de plantas son fuentes naturales potencialmente viables para la producción de biorepelentes que contribuyan en el control integrado de T. castaneum.

Essential oil nanoemulsion: An emerging eco-friendly strategy towards mosquito control.

Mosquito borne diseases are impeding to human health due to their uncontrolled proliferation. Various commercial insecticides currently used become ineffective due to the resistance acquired by mosquitoes. It is necessary and a priority to combat mosquito population. Plant-based products are gaining interest over the past few decades due to their environment friendliness and their effectiveness in controlling mosquitoes along with their lack of toxicity. Essential oil nanoemulsions are found to be highly effective when compared to their bulk counterparts. Due to their nano size, they can effectively interact and yield 100 % mortality with the mosquito larvae and encounter with minimal concentrations. This is the main advantage of the nano-sized particles due to which they find application in various disciplines and have also received the attention of researchers globally. There are various components present in essential oils that have been analysed using GC-MS. These findings reflect the challenge to mosquitoes to gain resistance against each component and therefore it requires time. Commercially used repellants are synthesised using materials like DEET are not advisable for topical application on human skin and essential oil nanoemulsions could be an ideal non toxic candidate that can be used against mosquito adults and larvae. However, there are other synthesis, optimisation parameters, and toxicity towards non-target organisms that have to be taken into account when essential oil nanoemulsions are considered for commercial applications. Here we review the strategies used by the nanoemulsions against the mosquito population. Apart from the positive effects, their minor drawbacks also have to be scrutinised in the future.

Confirmation of the steroid hormone receptor-mediated endocrine disrupting potential of fenvalerate following the Organization for Economic Cooperation and Development test guidelines, and its estrogen receptor α-dependent effects on lipid accumulation.

In this study, we focused on confirming the steroid hormone receptor-mediated endocrine-disrupting potential of the pyrethroid insecticide fenvalerate and unraveling the underlying mechanisms. Therefore, we assessed estrogen receptor-α (ERα)- and androgen receptor (AR)-mediated responses in vitro using a hormone response element-dependent transcription activation assay with a luciferase reporter following the Organization for Economic Cooperation and Development (OECD) test guidelines. We observed that fenvalerate acted as estrogen by inducing the translocation of cytosolic ERα to the nucleus via ERα dimerization, whereas it exhibited no AR-mediated androgen response element-dependent luciferase activity. Furthermore, we confirmed that fenvalerate-induced activation of ERα caused lipid accumulation, promoted in a fenvalerate-dependent manner in 3 T3-L1 adipocytes. Moreover, fenvalerate-induced lipid accumulation was inhibited in the presence of an ERα-selective antagonist, whereas it remained unaffected in the presence of a glucocorticoid receptor (GR)-specific inhibitor. In addition, fenvalerate was found to stimulate the expression of transcription factors that promote lipid accumulation in 3 T1-L1 adipocytes, and co-treatment with an ERα-selective antagonist suppressed adipogenic/ lipogenic transcription factors at both mRNA and protein levels. These findings suggest that fenvalerate exposure may lead to lipid accumulation by interfering with ERα activation-dependent processes, thus causing an ERα-mediated endocrine-disrupting effect.

Farmer perceptions, knowledge, and management of fall armyworm in maize production in Uganda.

Spodoptera frugiperda (J.E. Smith), fall armyworm (FAW), a polyphagous Noctuid pest, was first reported in Uganda in 2016. Farmers were trained to identify and manage the pest, but there was a lack of information on farmer knowledge, perceptions and practices deployed to control it. Therefore, we conducted a survey to assess maize farmers' knowledge, perceptions and management of the pest during the invasion. We interviewed 1,289 maize farmers from 10 maize-growing agro-ecological zones (AEZ) of Uganda using well-structured questionnaires. The data were analyzed using R version 4.2.3. The respondents faced many constraints, including pests, drought, poor soils and labor constraints. Among the pests, FAW was ranked by most (85%) of the respondents as the number one pest problem in maize, and some farmers reported having noticed it way back in 2014. By 2018, more than 90% of the farmers had seen or heard about FAW, and about 80% saw FAW in their fields. The most common FAW symptoms reported by maize farmers were windowing, near tunnel damage, and holes on the cobs. The developmental stages of FAW identified by farmers included eggs (10%), young larvae (78.7%), mature larvae (73.5%) and adult moths (6.7%). Insecticides were the major control tactic, although some farmers used plant extracts, hand-picking, sand, and ash. Farmers sourced information on FAW from various sources, including fellow farmers, radio/TV, extension agents, input dealers, print media, research and NGO extension. There is a need to package clear and uniform information for the farmers and to develop and promote a sustainable solution for FAW management, including harnessing biological control and cultural practices.