Search Results (246)

Chronic exposure to even low levels of pesticides is a serious public health issue, mainly due to the role of oxidative stress in damaging the liver and promoting cancer. This has driven interest in finding natural, plant-based antioxidants that can counteract this kind of chemical injury. In this study, we tested whether a methanol extract from the leaves of Pteropyrum scoparium (PSE) could protect the liver against oxidative harm caused by four common pesticides: acetochlor, deltamethrin, thiamethoxam, and rotenone. Chemical analysis showed that the extract contains high levels of phenolics (345.1 ± 7.6 mg GAE/g) and flavonoids (17.3 ± 1.3 mg CAE/g). GC–MS profiling revealed a diverse set of compounds, including fat-soluble antioxidants like squalene, α-tocopherol, and γ-sitosterol, and water-soluble phenolics like pyrogallol and catechol, suggesting PSE is equipped with a multi-layered antioxidant defence. In the animal experiment, rats were given each pesticide for 30 days, with or without PSE. All four pesticides caused clear oxidative stress in the liver: glutathione (GSH), total antioxidant capacity (TAC), antioxidant enzymes activities dropped, while markers of lipid damage (MDA) and free radical activity (DPPH) rose. Co-administration of PSE significantly restored GSH, TAC and antioxidant enzymes levels and reduced MDA and residual DPPH values compared to pesticide-only groups; these parameters were statistically comparable to the controls (p > 0.05), indicating a substantial recovery of hepatic redox balance. Histopathological examination of liver tissues confirmed these findings, as pesticide treatment caused visible liver injury; deltamethrin and thiamethoxam led to congestion in central veins, while rotenone and acetochlor triggered clusters of inflammatory Kupffer cells. In animals that also received PSE, liver structure remained largely normal, with much less congestion and inflammation. These results show that the combination of antioxidant constituents in PSE might contribute to hepatoprotection through redox modulation and preservation of endogenous antioxidant balance, as suggested by the observed biochemical and histological improvements. Full article

Predatory mites are key natural enemies in perennial crops, and their conservation is fundamental to ensure biocontrol of several pests. Yet their susceptibility to insecticides may compromise their role in Integrated Pest Management (IPM). In the past, pyrethroids proved to be poorly selective insecticides towards predatory mites, but in various countries their use recently increased in fruit orchards to counteract invasive pests. In this study, we assessed the effects of pyrethroids on the predatory mite Amblyseius andersoni through field experiments in apple orchards and laboratory assays on different strains. Field trials showed that A. andersoni populations remained unaffected by pyrethroid applications. Laboratory assays revealed intraspecific variation in A. andersoni populations: one commercial strain was highly susceptible to deltamethrin, whereas other commercial or field-collected strains were not affected, with no apparent sub-lethal effect on fecundity. These results underscore the contrasting susceptibility among predatory mite strains. From an IPM perspective, the lack of susceptibility to pyrethroids in A. andersoni may sustain biological control where insecticide use is unavoidable. Our findings stress the importance of evaluation procedures in toxicological studies, in particular the need to compare different strains, and of further investigation on predatory mite resistance. The implications for conservation programs in perennial cropping systems are addressed hereafter. Full article

Grain protectants are insecticide formulations applied directly to raw grain to prevent and control insect infestations in bulk storage; however, their efficacy depends on insect species, commodity, and grain quality. The objective of this study was to determine the residual efficacy of four commercially available grain protectants, Gravista^® (deltamethrin + methoprene + PBO), Diacon^® IGR (methoprene), Sensat^TM (spinosad), and EverGreen^® (pyrethrin), applied to sorghum and held for 28 weeks, against Rhyzopertha dominica (F.) and Sitophilus oryzae (L.). Subsamples were collected every four weeks and infested with 10 adults of either species. Adult mortality was assessed after seven days and progeny, frass, and insect-damaged kernels were evaluated after eight weeks. Rhyzopertha dominica was more susceptible to all insecticides compared to S. oryzae, and had fewer progeny compared to control sorghum. Spinosad-treated sorghum resulted in 100% adult mortality in R. dominica compared to 30–39% in S. oryzae. There was an overall decline in kernel moisture content, which may have impacted progeny of both species in the control and insecticide-treated sorghum. These findings highlight the influence of insecticide formulation, insect species, and grain moisture content on the long-term efficacy of grain protectants applied to sorghum. Full article

Insecticide resistance in Aedes aegypti (Linnaeus, 1762) poses a major challenge for vector control programs, undermining the effectiveness of chemical tools to mitigate both nuisance biting and the transmission of vector-borne diseases. Previous studies have documented widespread resistance to multiple adulticide active ingredients across Florida, particularly pyrethroids, along with high prevalence of knockdown resistance (kdr) mutations. Continued resistance monitoring is essential for guiding treatment decisions and detecting shifts in susceptibility over time. In collaboration with mosquito control programs across Florida, we assessed the susceptibility of 78 Ae. aegypti populations to up to six active ingredients, conducting 396 independent CDC bottle bioassays and calculating hazard ratios relative to a susceptible Ae. aegypti strain. For pyrethroids, 24 h post-exposure mortality was used to evaluate phenotypic recovery from knockdown. Hazard ratios revealed Ae. aegypti populations were more susceptible to organophosphate adulticide active ingredients, while the lowest hazard ratios, indicating higher resistance, were observed for sumithrin, deltamethrin, etofenprox, and permethrin, respectively. Evidence of knockdown resistance and recovery after 24 h was present across all pyrethroid exposures, with the highest levels following treatment with etofenprox and sumithrin. These findings confirm that pyrethroid resistance remains a significant barrier to Ae. aegypti control and provide updated, operationally relevant resistance data that can complement existing guidance and support evidence-based vector management strategies. Full article

Background: Pyriproxyfen (PPF), a juvenile hormone analog, is a promising chemical for autodissemination strategies, where mosquitoes aid in transferring insecticides to their breeding sites. This study evaluated the effects of sublethal PPF doses on Anopheles arabiensis fitness (fecundity, fertility, and body size) and pyrethroids susceptibility across three generations. Methods: Laboratory-reared, pyrethroid-resistant mosquito larvae were exposed once to sublethal PPF concentrations of (0.0003, 0.0006, 0.0008, and 0.001 mg a.i./L), which caused emergence inhibition rates of 5%, 10%, 15%, and 20%, respectively, alongside a control group. Emerged adults were tested for susceptibility to 0.75% permethrin, 3.75% permethrin, and 0.05% deltamethrin using WHO tube bioassays. Knockdown was recorded at 1 h, mortality at 24 h post-exposure, while fecundity, fertility, and body size were measured across three generations. Results: First-generation Anopheles arabiensis emerging from PPF-treated larvae showed reduced susceptibility to 0.75% permethrin and 0.05% deltamethrin compared to controls. Mortality from permethrin dropped from 22.7% in the controls to 11% and then 3% at 0.0003 and 0.001 mg a.i./L. For deltamethrin, mortality fell from 62.7% to 36% and then 23.3% at the same concentrations. Knockdown at 60 min was also significantly reduced, with permethrin KDT₆₀ dropping from 41.3% in controls to 9.3% and 3.3%, and deltamethrin KDT₆₀ from 79.7% to 66.7% and 65%. No significant differences were observed in subsequent generations (p > 0.05). PPF exposure also induced notable fitness costs in the first generation: mean wing length decreased from 3.07 mm in controls to 2.88–2.66 mm (6–13% reduction), mean egg production dropped from 30.1 to 13.9–18.8 eggs per female (37–54% reduction), and egg hatching rate declined from 87% to 79–82% (6–9% reduction). Conclusions: These findings suggest that sublethal PPF doses can temporarily enhance insecticide resistance without leading to heritable resistance and negatively impact key mosquito fitness traits. PPF may thus be a valuable addition to integrated vector management strategies. Full article

Extensive application of deltamethrin on agricultural products results in serious contamination of the environment. Its negative impact on environmental and public health necessitates the development of environmental remediation technologies. Detailed investigations of microbial degradation of deltamethrin may be useful for the development of bioremediation strategies. In this study, the deltamethrin removal capability of a bacterial strain, Microbacterium sp., previously isolated from the gut of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) was first investigated. When 3 mL of the bacterial solution (OD₆₀₀ = 1) was inoculated into 97 mL of MS media containing 200 μg/mL deltamethrin, it could remove 45.7% deltamethrin after 64 h of incubation. This strain grew fastest in LB media with an inoculum volume of 3% in pH 7 at 175 rpm, 25 °C. To enhance its environmental tolerance, this strain was immobilized with sodium alginate. Microbacterium sp.-containing calcium alginate microspheres (CAMs) exhibited an enhanced deltamethrin removal capability compared to free bacteria, and CAMs generated by immobilization with 2% sodium alginate and 3% CaCl₂ cross-linking for 4 h possessed the maximum deltamethrin removal capability. The ultrastructure of Microbacterium sp.-containing CAMs prepared under optimal conditions was a three-dimensional mesh structure with pores and dense features, and the bacteria grew well in the immobilized carrier. After being reused five times, the deltamethrin removal rate of immobilized Microbacterium sp. still reached over 50%. When Microbacterium sp. was inoculated into deltamethrin-contaminated water or soil for 48 h, the deltamethrin removal rate of immobilized bacteria was 1.4 times higher than that of free bacteria. These results suggest that Microbacterium sp.-containing CAMs possess an excellent deltamethrin removal capability and good reusability, showing great potential for the remediation of deltamethrin-contaminated environments. Full article

Insecticide resistance in insects poses a serious problem in population control of arthropod vectors and spreaders of human and animal diseases. Metabolic resistance to insecticides is facilitated by detoxification system enzymes, including glutathione-S-transferases (GSTs) involved in phase II of xenobiotic biotransformation. The aim of this study was to analyze the glutathione-S-transferase activity and the expression level of different class GST genes in Musca domestica. The test subjects were larvae and 3–5-day-old adults of a laboratory susceptible strain (LabTY) and a field deltamethrin-tolerant population (Nik). Based on the LC50 values, the Nik strain showed sensitivity to chlorpyrifos and chlorfenapyr and tolerance to deltamethrin with a remarkable increase in the level of resistance in males compared to females. Expression analysis of eight GST genes revealed that the expression of the GST-E12 gene (Epsilon class) was significantly elevated and the GST-S1 gene (Sigma class) was significantly decreased in the Nik strain across all groups (larvae, females, and males), with the most pronounced difference in females. A pronounced sexual dimorphism was observed: the expression of most GST genes was significantly higher in males than in females in both strains. For the first time, a consistent male-specific overexpression of multiple GST genes has been demonstrated in M. domestica. Full article

Deltamethrin is widely employed for crop pest control, aquaculture pond clearance, and fish parasite treatment. Due to its photostability, thermal resistance, and lipophilicity, deltamethrin has a high potential for environmental persistence and bioaccumulation in aquatic organisms. This poses significant risks to aquatic ecosystems, the safety of aquatic products, and human health. Although our previous study isolated Paracoccus sp. P-2 from crab culture pond sediment and demonstrated its high efficiency in degrading deltamethrin, the underlying mechanisms and enzyme characteristics remain unelucidated. In this study, genomic analysis revealed that the Paracoccus sp. P-2 genome was assembled into 3 contigs with a total length of 4,451,812 bp, an average G + C content of 67.73%, and a total of 4462 predicted genes. In addition, a quantitative analysis of the Paracoccus sp. P-2 proteome identified 3052 proteins, with 2705 exhibiting significant differential abundance (FC ≥ 1.5 or FC ≤ 0.6667, and p-value ≤ 0.05) following deltamethrin exposure. Among them, many upregulated differentially expressed proteins were enriched in carbohydrate and energy metabolism pathways, indicating that Paracoccus sp. P-2 enhances its basal metabolic activity in response to deltamethrin-induced stress. More importantly, enzymes belonging to hydrolases, decarboxylases, and those involved in multiple xenobiotic metabolic pathways were upregulated and are likely to participate in the degradation of deltamethrin. This study elucidates the impact of deltamethrin on bacterial metabolism and its degradation mechanism by Paracoccus sp. P-2, providing crucial insights and microbial resources for researching pyrethroid biodegradation. Full article

Cereal grains make up a significant part of both human and animal diets; therefore, they should meet pesticide residue standards and be characterized by the lowest possible concentrations of these residues. Known for its strong oxidizing properties, ozone is gaining popularity as a natural agent for eliminating chemical contaminants at the stages of production, processing, and storage of raw materials of plant origin. The present study is the first to assess the effect of ozonation on the behavior of 12 (seven systemic and five non-systemic) compounds. The procedure was conducted in two time variants (30 and 60 min) for three cereal types: barley, wheat, and rye. Treatment efficiency was confirmed through instrumental determination conducted using the LC–MS/MS technique based on the QuEChERS protocol. The level of systemic compounds was reduced by 37–82%, and of non-systemic ones by approximately 72–95%. The reduction in difenoconazole amounted to only 39%, whereas the highest decrease of 95% was recorded for deltamethrin. The rate of pesticide degradation occurred in the following sequence: rye > wheat > barley. The results show that ozonation of cereal grains may successfully support assurance of food and feed safety. Full article

Visceral leishmaniasis is a zoonosis commonly caused in Brazil by the parasite Leishmania infantum. This protozoan parasite can infect several species of mammals, with dogs being the main reservoir in urban areas. Several methods are used to prevent the disease, including collars impregnated with 4% deltamethrin to prevent contact between the sandfly and the animal, and vaccines. Vaccines aim to stimulate an immune response that can effectively fight the parasite, with the Th1 immune response being the most desired. There are several research groups around the world dedicated to testing new immunogens against Leishmania spp. and there are currently two commercially available vaccines used to prevent the disease, Neoleish^® and Leti-Fend^®. Leish-Tec^®, a vaccine previously licensed for use in dogs in Brazil, was suspended in May 2023 due to non-compliance in some batches. This also happened with CaniLeish^®, which was discontinued by the European Commission in October 2023. These vaccines have different characteristics that influence their use as a public health measure, and therefore the objective of this review is to describe these immunogens, their characteristics, and their use as a collective prevention measure for canine visceral leishmaniasis. Full article

Pesticides are used in agriculture to protect crops from disease. Among these, the herbicide glyphosate, the insecticide deltamethrin, and the fungicides propamocarb and tebuconazole are approved for use in Europe. These pesticides, along with their metabolites, have been detected in the environment including in food and water sources. Human biomonitoring studies have confirmed the presence of these compounds in biological samples, indicating persistent exposure even among the general population, unrelated to agricultural occupations. Consequently, numerous studies have investigated the health effects of these four pesticides and their metabolites. This review focuses on their impacts on gut health primarily the gut microbiota, inflammation, metabolism, cancer and gut–brain axis. Epidemiological studies were included to assess health risks among various groups including adults, children and pregnant women. Animal and in vitro models have been employed to explore in a more controlled and targeted way the physiological and biochemical effects observed in epidemiological studies. Despite some controversy, pesticides and their metabolites have been linked to gut dysbiosis, inflammatory bowel disease (IBD), metabolic disorders, cancer and neurodevelopmental disorders. Mechanistically, these pesticides influence gut microbiome composition, sugar and lipid metabolism, oxidative stress, inflammatory pathways, cell death, oncogenic signalling pathways, endocrine disruption, and epigenetics. However, further studies are needed to confirm these risks and health impacts, particularly concerning low-dose, long-term exposure as experienced by the general population. A comprehensive investigation of these effects is essential, incorporating dietary factors, age, sex, health status, and the cumulative impact of multiple pesticides, to develop a thorough risk assessment. Full article

Carboxylesterases (CCEs) have been demonstrated to be involved in pyrethroid resistance in insect species. This study aims to investigate CCE-mediated resistance mechanisms in Anopheles sinensis, a major malaria vector. Through comparative transcriptomics of a deltamethrin-resistant strain (CQ-LR) versus susceptible strain (WX-LS) of An. sinensis, we identified differentially expressed CCE genes across five developmental stages, five tissues, and three time points post-blood-meal. Four candidate genes (AsAe9, AsAe10, AsAce2, AsUn5) showed significantly upregulated expression. Subsequent qRT-PCR validation across four field-derived resistant strains (WX-LR, AH-LR, YH-LR, CQ-LR) and the susceptible strain confirmed significant upregulation of AsAe9, AsAe10, AsAce1, AsAce2, and AsBe4 in more than two resistant populations. RNAi-based functional validation showed that silencing AsAe10 or AsBe4 in the WX-LR strain significantly decreased knockdown time and raised 24 h mortality upon diagnostic deltamethrin exposure, with AsAe10 silencing having the strongest effect. This study identifies CCE genes involved in deltamethrin resistance in An. sinensis, providing valuable insights into the resistance mechanisms of pyrethroid and a theoretical basis for mosquito resistance management. Full article

Propsilocerus akamusi (Tokunaga, 1938) larvae serve as key bioindicators for water quality assessment. This study identifies optimal reference genes for RT-qPCR under diverse experimental conditions. Fifteen candidate genes commonly employed in other insect species were selected, candidate genes commonly used in other insect species. Homologous genes were identified in the P. akamusi genome through sequence alignment with their Drosophila melanogaster counterparts. Expression stability across developmental stages, body parts, temperature variations, and deltamethrin/nickel chloride exposures was systematically evaluated using geNorm, NormFinder, BestKeeper, and ΔCt methods. RPL32 exhibited the highest expression stability across different body parts of adults under varying temperature conditions, and RPS11 and RPL8 showed the greatest stability across developmental stages and in larvae exposed to different temperatures. Furthermore, under nickel chloride and deltamethrin treatments, RPS11 and RPL8 maintained the highest expression stability. The results indicated that the expression stability of reference genes varied under different conditions. Among different body parts of adults, RPL32 and RPL4 exhibited the most stable expression. Across different developmental stages, RPS11 and RPL8 performed best in terms of expression stability. Under different temperature treatments, RPL32 and RPL4 remained stable in adults, while RPS11 and RPL8 showed the greatest stability in larvae. Similarly, under nickel chloride and deltamethrin treatments, RPS11 and RPL8 demonstrated the most stable expression in larvae. Through the above research, we can advance ecosystem-impact insights and bolster environmental protection and water quality monitoring. Full article

Insecticide resistance monitoring is essential for effective mosquito control. This study compared CDC Bottle Bioassays (BBAs) using technical and formulated insecticides (deltamethrin/Deltagard and malathion/Fyfanon EW) against the Culex pipiens complex (Fogg Rd) and Culex tarsalis Coquillett (Vic Fazio). BBAs indicated resistance to deltamethrin and emerging resistance to malathion in Fogg Rd, as well as resistance to both in Vic Fazio. Field trials, however, showed high efficacy: Deltagard caused 97.7% mortality in Fogg Rd and 99.4% in Vic Fazio. Fyfanon EW produced 100% mortality in Fogg Rd but only 47% in Vic Fazio. Extended BBA endpoints at 120 and 180 min aligned better with field outcomes. Deltagard achieved 100% mortality at 120 min in both populations; technical deltamethrin reached 85.7% (Fogg Rd) and 83.5% (Vic Fazio) at 180 min. Fyfanon EW and malathion showed similar performance: 100% mortality was achieved in Fogg Rd by 120 min but was lower in Vic Fazio; malathion reached 55%; and Fyfanon EW reached 58.6% by 180 min. Statistical analysis confirmed that BBAs using formulated products better reflected field performance, particularly when proprietary ingredients were involved. These findings support the use of formulated products and extended observation times in BBAs to improve operational relevance and resistance interpretation in addition to detecting levels of insecticide resistance. Full article

Acaricide usage has led to the growing problem of resistance in ticks. A heavy tick burden and the presence of ticks on animals throughout the year, despite the monthly application of acaricides, in farms in the United Arab Emirates formed the motivation for this study. The objectives of this research were as follows: (a) to assess the acaricide resistance status of the most prevalent tick Hyalomma spp. to widely used acaricides Cypermethrin and Deltamethrin; (b) to identify the association of farm management practices and farm-level risk factors with the failure of tick treatment (acaracide resistance). A total of 1600 ticks were collected from 20 farms located in three different regions of Abu Dhabi Emirate including Al Ain (n = 10), Al Dhafra (n = 5), and Abu Dhabi (n = 5). The ticks were subjected to an in vitro bioassay adult immersion test (AIT) modified with a discriminating dose (AIT-DD) against commercial preparations of Cypermethrin and Deltamethrin. A questionnaire was designed to collect metadata and information on farm management and the farm-level risk factors associated with routine farm practices relating to the treatment and control of tick and blood parasite infections in camels and small ruminant populations. Hyalomma anatolicum and Hyalomma dromedarii were identified among the collected ticks, with H. anatolicum being the most prevalent tick species (70%) in the present study. The test results of the in vitro bioassay revealed varied emerging resistance to both of the acaricides in the majority of the three regions; fully susceptible tick isolates with zero resistance to Deltamethrin were recorded in one farm at Al Ain and two farms in the Abu Dhabi region. A questionnaire analysis showed that the failure of tick treatment in farms varied with the presence or absence of vegetation areas, types of animal breeds, and management practices. This study reports the emergence of resistance in ticks to Cypermethrin and Deltamethrin across the Abu Dhabi Emirate, indicating a strict warning for the cautious use of acaricides. There is also a need to improve awareness about sound tick management and control practices among farm owners through a multidisciplinary approach adopting integrated pest management strategies that engage farmers, veterinarians, and policy makers. Full article