Concentrations Of Diflubenzuron Research Articles

Chronic exposure to low concentration of diflubenzuron and pyriproxyfen induces brain oxidative stress and inflammation and alters locomotion in zebrafish (Danio rerio)

Diflubenzuron (DFB1) and pyriproxyfen (PPF) are pesticides widely used in agriculture and urban environments to control insect actions. The aim of this study was to evaluate the effects of chronic 30-day exposure to DFB (0.025 and 0.125 mg/L) and PPF (0.379 and 0.758 mg/L) on the behavior of juvenile zebrafish (Danio rerio). Fish were exposed to insecticides from early stage (4 h post fertilization) to 30 days post fertilization (dpf). At 45 dpf, fish were evaluated in the novel tank test, social behavior test, and mirror aggressive test. Brain gene expression related to oxidative stress and inflammation was also evaluated. DFB reduced locomotor parameters in the novel tank and aggression tests, while it induced to hyperactivity in the social behavior test. PPF reduced anxiety-like behavior, measured by the time spent in risky areas of the novel tank, and reduced aggression against the mirror image. There was a significant reduction in mRNA levels of the nfe2l2 gene (∼0.54 fold downregulated) and increase in levels of cat (PPF ∼1.8 fold change), gsr (PPF ∼1.5 fold change), gpx1a (PPF ∼1.6 and DFB 1.1 fold change), tnf-α (PPF 1.9 and DFB 2.2 fold change), and il-6 (PPF ∼1.2 and DFB 2.3 fold change). These endpoints are indicative of the threatening effects of insecticides to aquatic organisms and the need for alternative methods to control pests by using less harmful and safer substances for animal and human well-being, as well as for the environment.

Diflubenzuron larvicide auto-dissemination: A modeling study

Proposing substitutes for Pyriproxyfen (PPF) in the auto-dissemination strategy is essential to ensure the continuity of the strategy in the field, especially in the case of the emergence of populations resistant to this larvicide. One possible substitute among the compounds already in use in Brazil is the larvicide Diflubenzuron (DFB). The equation that defines the proportion of oviposition sites (habitats) contaminated by the auto-dissemination strategy was modified to account for the number of visits required to reach the necessary concentration of DFB for contamination, considering scenarios with varying numbers of oviposition sites and mosquito densities. The dissemination was evaluated in oviposition sites of 2 L, 1.5 L, 1 L, 0.5 L, 0.2 L, and 0.1 L. The minimum concentration of active ingredient (a.i) of DFB required for a commercial product to contaminate at least 50% of oviposition sites was also investigated, along with the impact of other vector control methods, such as the removal/destruction of oviposition sites and the use of insecticides to kill adult ‘females, on the auto-dissemination approach. The use of pure DFB compounds enabled contamination efficiency of more than 50% in oviposition sites with a volume of less than 2 L in scenarios with fewer oviposition sites. On the other hand, with the use of the commonly used concentration of the product, similar efficacy was only achieved in oviposition sites of 0.1 L and 0.2 L in medium and high infestation scenarios. Strategies that reduce the number of available oviposition sites work synergistically with the auto-dissemination strategy, making it possible to use less concentrated products and contaminated sites of larger volume. The strategy proved to be resilient in situations of insecticide application according to the concentration of DFB used, abundance of females, and low number of oviposition sites. Increasing the number of dissemination traps on the field also contributes to better results, especially for oviposition sites of 0.5 L and 1 L. The results of the model obtained under the stipulated conditions provide further support for the potential use of DFB as a substitute for PPF in the auto-dissemination strategy.

Diflubenzuron Mass Concentration Determination Method in Pesticides Using High-Performance Liquid Chromatography.

Pesticides are actively used in agriculture to protect crops from pests, and accurate determination of the concentration of their active ingredient is critical to ensuring their efficacy and safety. The research aims to develop a methodology that will enable the accurate determination of the mass concentration of diflubenzuron, a widely used active ingredient in pesticide formulations. This is achieved through the use of high-performance liquid chromatography (HPLC). The proposed method for determining the mass concentration of diflubenzuron using HPLC was developed through a series of experiments and optimisation steps. The sample preparation procedure was optimised to extract the maximum amount of diflubenzuron from the pesticide formulation. The chromatography conditions were optimised to separate diflubenzuron from other components in the sample matrix. A calibration approach was established for accurate quantification of diflubenzuron in the sample based on peak area measurements. The developed method can be widely used in agriculture, where accurate determination of diflubenzuron concentrations in pesticide formulations is critical for proper application and regulatory compliance. Both regulatory organizations and pesticide manufacturers can use it for batch-release testing and quality control to evaluate the efficacy and safety of pesticide products. In addition, the method can serve as a valuable tool for researchers and analysts working with pesticide residues in crops and environmental monitoring studies. The optimised sample preparation, chromatography conditions, and calibration approach provide reliable and reproducible results.

Embryotoxic Effects of Pesticides in Zebrafish (Danio rerio): Diflubenzuron, Pyriproxyfen, and Its Mixtures.

Diflubenzuron (DFB) and pyriproxyfen (PPF) are larvicides used in crops to control insect plagues. However, these pesticides are known to impact non-target organisms like fish and mammals. Here, we aimed at assessing the embryotoxicity of purified DFB, PPF, and their mixtures in a non-target organism-zebrafish. Zebrafish embryos were exposed to different concentrations for 120 h: 0.025, 0.125, 0.25, 1.25, 2.5, and 10 mg/L of purified PPF and purified DFB, while we used 0.025 mg/L PPF + 10 mg/L DFB (Mix A), 0.125 mg/L PPF + 10 mg/L DFB (Mix B), and 0.25 mg/L PPF + 10 mg/L DFB (Mix C) for the mixtures of PPF + DFB. We observed mortality, teratogenicity, and cardiotoxicity. For the neurotoxicity tests and evaluation of reactive oxygen species (ROS) levels in the brain, embryos were exposed for 120 h to 0.379 and 0.754 mg/L of PPF and 0.025 and 0.125 mg/L of DFB. We established the LC50 for PPF as 3.79 mg/L, while the LC50 for DFB was not determinable. Survival and hatching were affected by PPF concentrations above 0.125 mg/L, DFB concentrations above 1.25 mg/L, and the lower pesticide mixtures. PPF exposure and mixtures induced different types of malformations, while a higher number of malformations were observed for the mixtures, suggesting a potentiating effect. Pesticides diminished avoidance responses and increased the levels of ROS across all concentrations, indicating neurotoxicity. Our findings underscore the detrimental impact of PPF and DFB exposure, spanning from biochemistry to morphology. There is a critical need to reconsider the global use of these pesticides and transition to more ecologically friendly forms of pest control, raising an alarm regarding repercussions on human and animal health and well-being.

Bioaccumulation and elimination, acute toxicity analysis and risk assessment of diflubenzuron in common carp (Cyprinus carpio)

Diflubenzuron has been applied in agriculture and aquaculture, and its residues in ecological environment and food chain could result in chronic exposure and long-term toxicity effects for human health. However, limited information is available regarding diflubenzuron levels in fish and associated risk assessment. This study performed the analysis for dynamic bioaccumulation and elimination distribution of diflubenzuron in carp tissues. The results indicated that diflubenzuron was absorbed and enriched by fish body along with higher enrichment in lipid-rich tissues of fish. The peak concentration in carp muscle reached 6-fold of diflubenzuron concentration in aquaculture water. The median lethal concentration (LC50) of diflubenzuron at 96 h was 12.29 mg/L, presented low toxicity to carp. Risk assessment results showed that the chronic risk from dietary exposure to diflubenzuron through carp consumption for Chinese residents of children and adolescents, adults and elderly people were acceptable, while posed a certain risk for young children. This study provided the reference for pollution control, risk assessment and scientific management of diflubenzuron.

Chronic diflubenzuron exposure causes reproductive toxic effects in female marine medaka (Oryzias melastigma)

Diflubenzuron, an insecticide commonly used in marine fish farming, has been detected in various marine environments. However, its potential impact on marine fish remains largely unknown. This study investigated the reproductive toxicity of chronic diflubenzuron exposure in female marine medaka (Oryzias melastigma). Marine medaka were exposed continuously to environmentally relevant concentrations of diflubenzuron (0.1, 1, and 10 μg/L) or a solvent control from the fertilized egg to adulthood. In exposed female marine medaka, the gonadosomatic index (GSI) and the number of laid eggs were significantly reduced. Moreover, diflubenzuron-exposed female marine medaka showed altered ovarian histopathology, with an increased relative proportion of immature oocytes and atretic follicles and a decreased relative proportion of mature oocytes. Maternal exposure to diflubenzuron also inhibited the development of the F1 generation, significantly reducing the hatching rate of F1 embryos and significantly increasing the malformation rate of F1 larvae. Furthermore, changes in hormone levels and expression of genes along the hypothalamus-pituitary-gonad-liver (HPGL) axis were observed, which may be the fundamental reason for all the reproductive toxic effects mentioned above. These results provide new insights into the impact of diflubenzuron on the female marine medaka reproductive system and underscore the importance of investigating the potential environmental risks of diflubenzuron in the marine environment.

Comparative Study of pesticides effects on Artemia salina (Leach, 1819) survival and morphology

The use of pesticides has grown over the years and their effects on ecosystems, especially aquatic ones, have been increasingly observed. Agricultural pesticides are responsible for a large part of pollution in aquatic environments, and can reach non-target organisms, harming biodiversity. In this research, the effects of common pesticides on mortality rate and morphology of the model specie Artemia salina were evaluated. Commercial eggs of A. salina were hatched during 24-36 hours, at 37⸰C. Then, nauplli were exposed to different concentrations of insecticides Bifenthrin, Imidacloprid, Diflubenzuron, and Glyphosate herbicide. The mortality rate and lethal concentrations (LC) of each pesticide were established after 24 hours of treatment. Morphological analyses were made after treatment with the LC25 and LC50 of each pesticide. The results obtained show that Bifenthrin, Imidacloprid and Glyphosate promote linear mortality of the non-target species A. salina, while for insecticide Diflubenzuron, the mortality curve followed a logarithmic model. In addition, Diflubenzuron and Glyphosate induce changes in the morphological parameters of this specie. These results contribute to highlight the harmful effects of agricultural pollutants upon aquatic invertebrates. Besides, the present study confirms that Diflubenzuron does not affect only target species, but also has negative interference with the morphology of non-target species. This result has environmental implication since several invertebrates, including those not harmful to agriculture, can contact with Diflubenzuron in agricultural places.

Diflubenzuron Induces Cardiotoxicity in Zebrafish Embryos.

Diflubenzuron is an insecticide that serves as a chitin inhibitor to restrict the growth of many harmful larvae, including mosquito larvae, cotton bollworm and flies. The residue of diflubenzuron is often detected in aquaculture, but its potential toxicity to aquatic organisms is still obscure. In this study, zebrafish embryos (from 6 h to 96 h post-fertilization, hpf) were exposed to different concentrations of diflubenzuron (0, 0.5, 1.5, 2.5, 3.5 and 4.5 mg/L), and the morphologic changes, mortality rate, hatchability rate and average heart rate were calculated. Diflubenzuron exposure increased the distance between the venous sinus and bulbar artery (SV-BA), inhibited proliferation of myocardial cells and damaged vascular development. In addition, diflubenzuron exposure also induced contents of reactive oxygen species (ROS) and malondialdehyde (MDA) and inhibited the activity of antioxidants, including SOD (superoxide dismutase) and CAT (catalase). Moreover, acridine orange (AO) staining showed that diflubenzuron exposure increased the apoptotic cells in the heart. Q-PCR also indicated that diflubenzuron exposure promoted the expression of apoptosis-related genes (bax, bcl2, p53, caspase3 and caspase9). However, the expression of some heart-related genes were inhibited. The oxidative stress-induced apoptosis damaged the cardiac development of zebrafish embryos. Therefore, diflubenzuron exposure induced severe cardiotoxicity in zebrafish embryos. The results contribute to a more comprehensive understanding of the safety use of diflubenzuron.

Molecular Characterization of Chitin Synthase Gene in Tetranychus cinnabarinus (Boisduval) and Its Response to Sublethal Concentrations of an Insecticide.

Simple SummaryIn this study, we identified chitin synthase 1 gene (TcCHS1) from Tetranychus cinnabarinus (Boisduval) and then explored the gene expression levels of TcCHS1 at different developmental stages of T. cinnabarinus. We also investigated the effects of sublethal concentrations of diflubenzuron on the toxicities and survivals of T. cinnabarinus eggs and larvae as well as TcCHS1 expression levels. Our results demonstrated that TcCHS1 was essential for growth and development, and diflubenzuron exposure affected chitin metabolism. This work was undertaken to establish a foundation for further research on the functions of chitin synthase. It will provide a new target for controlling of T. cinnabarinus in the agricultural ecosystem.The carmine spider mite, Tetranychus cinnabarinus (Boisduval), is one of the most important acarine pest species. At present, its control remains primarily dependent on using various chemical insecticides/acaricides in agricultural crops worldwide. To clarify the mechanism whereby T. cinnabarinus responds to insecticide exposure, we identified the chitin synthase 1 gene (TcCHS1) and then explored the gene expression levels of TcCHS1 at different developmental stages of T. cinnabarinus. We also investigated the effects of sublethal concentrations of diflubenzuron on the toxicities and survivals of T. cinnabarinus eggs and larvae as well as TcCHS1 expression levels. The full-length cDNA sequence contains an open reading frame (ORF) of 4881 nucleotides that encoded for a 1474 amino acid residues protein. The predicted TcCHS1 protein had a molecular mass of 168.35 kDa and an isoelectric point of 6.26, and its amino acid sequence contained all the signature motifs (EDR, QRRRW and TWGTR) of chitin synthases. The results of phylogenetic analyses demonstrated that the putative CHS1 amino acid sequence of T. cinnabarinus revealed high similarities with chitin synthases in other insects and mites. Additionally, at the molecular level, transcriptional analysis by real-time quantitative PCR in different developmental stages of T. cinnabarinus revealed that TcCHS1 mRNA was expressed in all stages, and highest in eggs and female adults, but lowest in deutonymphs. Furthermore, the results of toxicity bioassays indicated that diflubenzuron treatment resulted in high mortality rates in eggs and larvae of T. cinnabarinus. The mRNA expression levels of TcCHS1 from the eggs and larvae of T. cinnabarinus were up-regulated in response to sublethal concentrations of diflubenzuron exposures. Together, all these results demonstrate that diflubenzuron has ovicidal and larvicidal effects and TcCHS1 may play an important role in the growth and development of T. cinnabarinus and may disrupt the chitin biosynthesis, thereby controlling T. cinnabarinus populations.

Transaminase profile and hepatic histopathological traits in Piaractus mesopotamicus exposed to insecticide Diflubenzuron.

Diflubenzuron (DFB) is a widely used insecticide to control ectoparasites in fish farming. Although therapeutic concentrations (i.e., 50 to 100 mg/L) are safe as they fail to induce mortality, they can promote tissue changes. In Brazil, Pacu (Piaractus mesopotamicus) is a native species used for commercial production, and it remains crucial to determine underlying mechanisms to mitigate the potential effects of pathogens on productivity. The aim of this study was to analyze the transaminase profile and histopathological changes in the liver of P. mesopotamicus exposed to a DFB bath. Hence, the fish were exposed to an immersion bath containing a 70 mg/L nominal concentration of Difluchem 240 SC® (24% (m/m) DFB) for 30 (n = 10), 60 (n = 10), and 120 min (n = 10), every 24 h for 3 days. Following exposure, plasma transaminases and liver histology were analyzed. In DFB-exposed fish, levels of aspartate transaminase (AST) and alanine transaminase (ALT) were elevated when compared with the control at 30 and 60 min. Furthermore, liver morphology was altered based on exposure times. Compared with controls, the degree of reversible damage (degree of tissue change (DTC)) demonstrated high scores for all exposure times, with no difference between individual groups. Irreversible changes were increased in the 60 and 120-min baths. These findings highlight the impact of the therapeutic DFB concentration (i.e., 70 mg/L), revealing that 60-min and 120-min bathing induces irreversible and progressive hepatic changes.

<p><strong><span>Transcriptome analys</span></strong><strong><span>i</span></strong><strong><span>s of </span></strong><strong><em><span>Tetranychus cinnabarinus</span></em></strong><strong><span> responses to an insecticide exposure</span></strong></p>

Diflubenzuron, a benzoylphenylurea insecticide that interferes with chitin biosynthesis, causes arthropods to moult abnormally and die. However, its mechanism of action in Tetranychus cinnabarinus is still unclear. In order to explore the effects of different sublethal concentrations of diflubenzuron on T. cinnabarinus, we conducted a high-throughput RNA-seq technology to identify the variations in transcriptomic profile of T. cinnabarinus larvae. The results revealed that 470 and 49 differentially expressed genes were identified in LC50-and LC70-treated groups, comparing with the control. We also identified and analyzed the detoxification enzymes involved in the transcritome of T. cinnabarinus, including 34 cytochrome P450 genes, 17 glutathione-s-transferase genes (GSTs), 12 acetylcholinesterase genes (AChEs) and 9 ABC transporter genes. In addition, differentially expressed genes analysis showed that the gene expression levels of detoxification enzymes were generally enhanced. At the same time, seven and eleven genes were involved in chitin synthesis and degradation ways, respectively. The expression level of most genes involved in chitin synthesis and degradation pathway were generally up-regulated after exposure to sublethal concentrations of diflubenzuron. Moreover, for transcriptome validation, the mRNA expression results of ten specially expressed genes by quantitative real-time PCR demonstrated that these gene expression trends were consistent with that of the transcriptome data. Together, all these results suggested that sublethal concentrations of diflubenzuron exposure affected gene expression of major detoxification enzymes and chitin metabolism genes in T. cinnabarinus larvae. These findings may be helpful to further understand the possible molecular mechanism of benzoylphenylurea insecticides in T. cinnabarinus, as well as in other spider mites.

Impact of Diflubenzuron on Bombus impatiens (Hymenoptera: Apidae) Microcolony Development.

Reliance on the honey bee as a surrogate organism for risk assessment performed on other bees is widely challenged due to differences in phenology, life history, and sensitivity to pesticides between bee species. Consequently, there is a need to develop validated methods for assessing toxicity in non-Apis bees including bumble bees. The usefulness of small-scale, queenless colonies, termed microcolonies, has not been fully investigated for hazard assessment. Using the insect growth regulator diflubenzuron as a reference toxicant, we monitored microcolony development from egg laying to drone emergence using the Eastern bumble bee Bombus impatiens (C.), a non-Apis species native to North America. Microcolonies were monitored following dietary exposure to diflubenzuron (nominal concentrations: 0.1, 1, 10, 100, and 1,000 µg/liter). Microcolony syrup and pollen consumption was significantly reduced by diflubenzuron exposure. Pupal cell production was also significantly decreased at the highest diflubenzuron concentration assessed. Ultimately, diflubenzuron inhibited drone production in a concentration-dependent manner and a 42-d 50% inhibitory concentration (IC50) was determined. None of the dietary concentrations of diflubenzuron tested affected adult worker survival, or average drone weight. These data strengthen the foundation for use of this methodology, and provide valuable information for B. impatiens; however, more work is required to better understand the utility of the bumble bee microcolony model for pesticide hazard assessment.

Compatibility between Leptolegnia chapmanii and diflubenzuron and neem oil for the control of Aedes aegypti

Leptolegnia chapmanii is pathogenic to mosquito larvae. The compatibility between L. chapmanii and two insect growth regulators (IGR), diflubenzuron and neem oil, was evaluated. L. chapmanii was grown on culture media containing different concentrations of each IGR. The mycelial growth was significantly reduced with the highest concentrations of IGR (F6,98=268, p<0.05). However, the production of zoospores (F6,56=0.93, p>0.05) and the larval mortality of Aedes aegypti (F6,56=0.95, p>0.05) were not significantly different among treatments. Furthermore, the percentage of adult emergence in the presence of different concentrations of diflubenzuron or a neem formulation was determined, and the pathogenic activity of zoospores was evaluated at the concentrations that inhibit the emergence at 30, 50 and 90%. The pathogenicity of zoospores was not significantly different among treatments (F6,14=0.54, p>0.05), and the larval mortalities were above 90% in all cases.

Transcriptional plasticity of different ABC transporter genes from Tribolium castaneum contributes to diflubenzuron resistance

The development of insecticide resistance challenges the sustainability of pest control and several studies have shown that ABC transporters contribute to this process. ABC transporters are known to transport a large range of chemically diverse molecules across cellular membranes, and therefore the identification of ABC transporters involved in insecticide resistance is difficult. Here, we describe a comprehensive strategy for the identification of whole sets of ABC transporters involved in insecticide resistance using the pest beetle, Tribolium castaneum (Tc) as a model. We analyzed the expression of ABCA to ABCC genes in different tissues and developmental stages using larvae that were sensitive or resistant to diflubenzuron (DFB). The mRNA levels of several ABC genes expressed in excretory or metabolic tissues such as midgut, Malpighian tubules or fat body were markedly upregulated in response to DFB. Next, we monitored mortality in the presence of the ABC inhibitor verapamil, and found that it causes sensitization to DFB. We furthermore established a competitive assay for the elimination of DFB, based on Texas Red (TR) fluorescence. We monitored TR elimination in larvae that were treated with DFB or different ABC inhibitors, and combinations of them. TR elimination was decreased significantly in the presence of DFB, verapamil and the ABCC inhibitor MK-571. The effect was synergized when DFB and verapamil were both present suggesting that the transport of TR and DFB involves overlapping sets of ABC transporters. Finally, we silenced the expression of DFB-responding ABC genes by RNA interference and then followed the survival rates after DFB exposure. Mortality increased particularly when specific ABCA and ABCC genes were silenced. Taken together, we were able to show that different ABC transporters expressed in metabolic and excretory tissues contribute to the elimination of DFB. Up- or down-regulation of gene expression occurs within a few days already at very low DFB concentrations. These results suggests that transcriptional plasticity of several ABC genes allows adaptation of the efflux capacity in different tissues to eliminate insecticides and/or their metabolites.

Screening Aedes aegypti (Diptera: Culicidae) Populations From Pernambuco, Brazil for Resistance to Temephos, Diflubenzuron, and Cypermethrin and Characterization of Potential Resistance Mechanisms.

Resistance to chemical insecticides detected in Aedes aegypti (L.) mosquitoes has been a problem for the National Dengue Control Program (PNCD) over the last years. In order to provide deeper knowledge of resistance to xenobiotics, our study evaluated the susceptibility profile of temephos, diflubenzuron, and cypermethrin insecticides in natural mosquito populations from the Pernambuco State, associating these results with the local historical use of such compounds. Furthermore, mechanisms that may be associated with this particular type of resistance were characterized. Bioassays with multiple temephos and diflubenzuron concentrations were performed to detect and quantify resistance. For cypermethrin, diagnostic dose assays were performed. Biochemical tests were carried out to quantify the activity of detoxification enzymes. In addition, a screening of mutations present in the voltage-gated sodium channel gene (NaV) was performed in samples previously submitted to bioassays with cypermethrin. The populations under study were resistant to temephos and showed a positive correlation between insecticide consumption and the resistance ratio (RR) to the compound. For diflubenzuron, the biological activity ratio (BAR) ranged from 1.3 to 4.7 times, when compared to the susceptible strain. All populations showed resistance to cypermethrin. Altered enzymatic profiles of alpha, p-nitrophenyl acetate (PNPA) esterases and glutathione-S-transferases were recorded in most of these samples. Molecular analysis demonstrated that Arcoverde was the only population that presented the mutated form 1016Ile/Ile. These findings show that the situation is critical vis-à-vis the effectiveness of mosquito control using chemical insecticides, since resistance to temephos and cypermethrin is widespread in Ae. aegypti from Pernambuco.

Exposure to anti-mosquito insecticides utilized in rice fields affects survival of two non-target species, Ischnura elegans and Daphnia magna

Insecticides are commonly utilized to control mosquito larvae in rice fields. They can, however, have negative effects on both vertebrates and non-target invertebrate species. In this study, we examined the effects of pulse exposition to different concentrations of cypermethrin (0.15, 0.015, 0.0015 mg/L) and diflubenzuron (0.15, 0.015, 0.0015 mg/L) on egg hatching rate, larval growth, and larval survival in a damselfly, Ischnura elegans, and on survival of a crustacean, Daphnia magna. Insecticide exposure had significant negative effects on hatching rate in damselfly eggs. Exposed damselfly larvae also grew less and showed a higher mortality than control larvae. In Daphnia, the acute toxicity test (ISO 6341 in Water quality—determination of the inhibition of the mobility of Daphnia magna Straus (Cladocera, Crustacea)—acute toxicity test, Int Organ Stand Geneve, Geneva, 2012) showed an increased inhibition of mobility in the presence of insecticides. We observed a proportional response in relation to insecticide concentration, such that the highest exposure levels showed the largest reduction of vital performances. Our highest tested values correspond to those currently employed in agriculture. This study suggests that exposure to two common insecticides strongly affects non-target invertebrates even at very low concentration levels (cypermethrin 0.0015 mg/L and diflubenzuron 0.0015 mg/L).

Physiological and Biochemical Effects of Diflubenzuron and Chromafenozide on the House Fly,Musca domestica(Diptera: Muscidae)

The insecticidal action of two insect growth disruptors (IGDs): the chitin synthesis inhibitor, diflubenzuron, and the ecdysone agonist, chromafenozide, were evaluated against the house fly, Musca domestica, larvae. The LC25, LC50, and LC75 were used for each IGD. The total carbohydrate, protein and lipid contents were estimated, and the effects of these compounds on native protein, glycoprotein and lipoprotein patterns were investigated in third instar larvae (treated as second instars). Results of susceptibility tests demonstrated that chromafenozide is more toxic to the larvae than diflubenzuron. Application of the three lethal concentrations of diflubenzuron and chromafenozide to second instar larvae increased the total protein, carbohydrate and lipid contents in treated third instar larvae as compared to the control. The electrophoretic study revealed a reduction in native protein bands, as well as the appearance of new lipoprotein and glycoprotein bands in treated larvae. Results showed that both diflubenzuron and chromafenozide cause physiological disorders, biochemical changes as well as death of treated M. domestica larvae.

Development of a kinetic spectrophotometric method for insecticide diflubenzuron determination in water and baby food samples

A kinetic spectrophotometric method for determining residues of insecticide diflubenzuron 1(4-chlorphenyl)-3-(2,6-diflubenzoyl)urea (DFB) has been developed and validated. Kinetic method was based on the inhibitory effect of DFB on the oxidation reaction of sulfanilic acid (SA) by hydrogen peroxide in the presence of Co2+ ions in a phosphate buffer, which was monitored at 370 nm. DFB can be measured in the concentration interval 0.102 ? 3.40 ?g mL-1 and 3.40 ? 23.80 ?g mL-1. The detection and quantification limits of the method were calculated according to the 3? criteria and found to be 0.077 ?g mL-1 and 0.254 ?g Ml-1, respectively. The relative standard deviations for five replicate determinations of 0.102, 1.70 and 3.40 ?g mL-1 DFB were 2.08, 1.22 and 1.21 %, respectively, for the first concentration interval, and the recovery percentage values were from 94.12 to 97.35 %. HPLC method was used as a parallel method to verify results of the kinetic method. The kinetic method was successfully applied to determine diflubenzuron concentrations in spiked water and baby food samples after solid phase extraction of the samples. The F and t values at 95% confidence level are lower than the theoretical ones, confirming agreement of the developed and the HPLC method.

In vitro PPARγ agonistic potential of chitin synthesis inhibitors and their energy metabolism-related hepatotoxicity

The extensive use of chitin synthesis inhibitors (CSIs) in integrated pest management programs has a detrimental effect on the surrounding environment. Recent studies reveal that CSIs may affect non-target organisms at sublethal concentrations, highlighting the need for further ecological and health risk investigations of these compounds. In this study, we characterized the peroxisome proliferator-activated receptor γ (PPARγ) agonistic activity of fourteen CSIs in HepG2 cells using an in vitro reporter gene assay. Five of the tested CSIs showed remarkable PPARγ-mediated transactivation, and the relative agonistic potencies were diflubenzuron>chlorfluazuron>flucycloxuron>noviflumuron>flufenoxuron based on REC20 values. In addition, molecular docking indicated that different interactions may stabilize ligand binding to PPARγ. Next, we clarified that sublethal concentration of diflubenzuron caused a shift in cellular energy metabolism from the aerobic tricarboxylic acid (TCA) cycle to anaerobic glycolysis and this process was associated with the activation of PPARγ. These findings suggest that CSIs act as PPARγ agonists and exert diverse hepatotoxic effects by disrupting energy metabolism at sublethal concentrations.

Alterations in antioxidant enzyme activities and lipid peroxidation induced by diflubenzuron in the carmine spider mite, Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae)

ABSTRACTThe eggs, larvae, nymphs and female adults of the carmine spider mite, Tetranychus cinnabarinus (Boisduval) were treated using corresponding sublethal dosages (LC10–LC50) of diflubenzuron. Then we examined the effect on the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione-S-transferases (GSTs), the total antioxidant capacity (T-AOC) and malondialdehyde (MDA) content. The results showed that the activities of SOD, CAT and POD at different developmental stages increased with increasing of diflubenzuron concentration, but when diflubenzuron concentration continued to increase, the activities decreased. GSTs activities, T-AOC and MDA content increased with the increasing of diflubenzuron concentration. The change trend of GSTs activities was as follows: eggs < larvae < nymphs < female adults. T-AOC in both nymphs and female mites was higher than that in eggs and larvae, and MDA contents in larvae, nymphs and female adults were always higher than that of eggs. The increasing of MDA concentration indicated that diflubenzuron stress led to lipid peroxidation in organisms. In summary, diflubenzuron stress resulted in oxidative stress and antioxidant enzymes played an important role in reducing oxidative damage in the carmine spider mite.