Concentrations Of Fipronil Research Articles

Exploring RNA methylation as a promising biomarker for assessing sublethal effects of fipronil on honeybees (Apis mellifera L.)

Honeybees play a crucial role as pollinators for crops and are regarded as sensitive bioindicators of environmental health. The widespread use of pesticides poses a severe threat to honeybee survival. However, there is limited information available on the specific risks associated with fipronil exposure in honeybees, particularly concerning the impact on RNA methylation throughout their lifespan. This study aimed to evaluate the effects of sublethal concentrations of fipronil on RNA m6A and m5C methylations, along with the associated genes in honeybee larvae and newly emerged adults. LC-MS/MS analysis revealed a notable hypomethylation of m5C in larvae, while hypermethylation of m6A was observed in the adult brain. Significant changes in the expression of genes such as AmWTAP, AmYTHDF, AmALKBH4, AmALKBH6, AmALKBH8, AmNSUN5, AmNOP2, AmTET1, and AmYBX1 were observed in the adult brain, whereas alterations in the expression of AmNSUN2, AmMETTL14, AmALKBH1, AmALKBH4, AmALKBH6 AmALYREF, AmTET1, and AmYBX1 were observed in the larvae. Notably, the expression of AmALKBH1 was not detected in any fipronil-treated larvae, suggesting its potential as an early risk indicator for honeybee larvae in future assessments. This pioneering study provides insights into the effects of fipronil on RNA methylations in honeybees and explores the possibility of employing RNA methylation as a tool for assessing pesticide risks in this important pollinator species. These findings offer new perspectives on honeybee protection and the development of toxicity evaluation systems for pesticides.

Environmentally relevant concentrations of fipronil selectively disrupt venous vessel development in zebrafish embryos/larvae

The pesticide fipronil is widely dispersed in aquatic environments and frequently detected in the general population. Although the adverse effects on embryonic growth by fipronil exposure have been extensively documented, the early responses for its developmental toxicity are largely unknown. In the present study, we explored the sensitive targets of fipronil, focusing on vascular injury using zebrafish embryos/larvae and cultured human endothelial cells. Exposure to 5–500 μg/L fipronil at the early stage impeded the growth of sub-intestinal venous plexus (SIVP), caudal vein plexus (CVP), and common cardinal veins (CCV). The damages on venous vessels occurred at exposure to the environmentally relevant concentration as low as 5 μg/L fipronil, whereas no significant change was observed in general toxicity indexes. In contrast, vascular development of the dorsal aorta (DA) or intersegmental artery (ISA) was not affected. In addition, the mRNA levels of vascular markers and vessel type-specific function genes exhibited significant decreases in venous genes, including nr2f2, ephb4a, and flt4, but no appreciable change in arterial genes. Likewise, the more pronounced changes in cell death and cytoskeleton disruption were shown in human umbilical vein endothelial cells as compared with human aortic endothelial cells. Furthermore, molecular docking supported a stronger affinity of fipronil and its metabolites to the proteins correlated with venous development, such as BMPR2 and SMARCA4. These results reveal the heterogeneity in developing vasculature responsive to fipronil's exposure. The preferential impacts on the veins confer higher sensitivity, allowing them to be appropriate targets for monitoring fipronil's developmental toxicity.

Adverse effects of contamination by fipronil and its derivatives on growth, molting, and gene expression in the mysid crustacean, Americamysis bahia, in Japanese estuaries

Concentrations of fipronil (Fip) and several of its derivatives were detected in samples from four rivers and four estuaries in Japan. LC–MS/MS analysis detected Fip and its derivatives, except for fipronil detrifluoromethylsulfinyl, in almost all samples. The total concentrations of the five compounds were approximately two-fold greater in river water (mean: 21.2, 14.1, and 9.95 ng/L in June, July, and September, respectively) compared to those in estuarine water (mean: 10.3, 8.67, and 6.71 ng/L, respectively). Fipronil, fipronil sulfone (Fip-S), and fipronil sulfide (Fip-Sf) represented more than 70 % of all compounds. This is the first report to demonstrate the contamination of estuarine waters of Japan by these compounds. We further investigated the potentially toxic effects of Fip, Fip-S, and Fip-Sf on the exotic mysid, Americamysis bahia (Crustacea: Mysidae). The lowest effective concentrations of Fip-S (10.9 ng/L) and Fip-Sf (19.2 ng/L) on mysid growth and molting was approximately 12.9- and 7.3-fold lower than Fip (140.3 ng/L), suggesting they had higher toxicity. Quantitative reverse transcription polymerase chain reaction analysis revealed that ecdysone receptor and ultraspiracle gene expression were not affected after 96-h of exposure to Fip, Fip-S, and Fip-Sf, suggesting that these genes may not be involved in the molting disruption induced by Fip, Fip-S, and Fip-Sf. Our findings suggest that environmentally relevant concentrations of Fip and its derivatives can disrupt the growth of A. bahia by promoting molting. However, further studies are required to elucidate its molecular mechanism.

Exposure to fipronil, 2,4-D and vinasse influences macroinvertebrate assemblage structure: An experimental mesocosm approach

Sugarcane is one of the main monocultures in Brazil and widely uses herbicide 2,4-D and fipronil insecticide. In addition, vinasse can be mentioned as it is widely used in this plantation. These compounds occurring simultaneously in the aquatic environment can potentiate the deleterious effects on organisms. Thus, this study aimed to evaluate the composition, abundance and ecological indices of the benthic macroinvertebrate community, as well as its ability to reestablish itself considering environmental contamination by the pesticides Regent® 800WG (active ingredient - a.i. fipronil) (F) and DMA® 806BR (a.i. 2,4-D) (D) and vinasse (V), alone and in mixtures: pesticides - M and the three contaminants - MV. The study was conducted using open-air mesocosms. The macroinvertebrate community was monitored by colonization structures, the physical-chemical parameters, metals and pesticides were determined and the effects of contaminants were evaluated over the exposure time in 1, 7, 14, 28, 75 to 150 days. A multiple regression was performed between the water parameters and significant relationships were found between parameters associated with vinasse contamination (pH, total nitrogen, turbidity, and dissolved oxygen) and concentration of fipronil and the ecological variables studied. Over time, changes were observed in the composition of the community. The dominance and richness increased in treatments V and MV. The family Chironomidae and subclass Oligochaeta were more sensitive to the treatment V and MV, while individuals from the families Phoridae, Ephydridae and Sciomyzidae were occasionally found (depending on the experimental time) in these treatments. The insects were sensitive to treatments F and M, disappearing in these mesocosms after contamination, reappearing only after 75 days. The results reveal that sugarcane management practices associated with the use of pesticides and vinasse as fertilizer pose risks to the macroinvertebrate community with consequences for the trophic chains, given its importance in freshwater ecosystems and adjacent terrestrial environments.

Magnetic Solid-Phase Extraction of Fipronil from Aqueous Solution and Eggshells Using Amine-Coated Iron Oxide Nanoparticles.

Fipronil, as a broad use insecticide, is regulated under directives and standards in many countries since it is classed as Class II moderately hazardous pesticide and Group C possible human carcinogen. In this study, amine coated iron oxide (NH2 -Fe3 O4 ) is used as a new adsorbent with high adsorption capacity in the removal of fipronil from aqueous solution and eggshells.The adsorption performance was studied through batch adsorption under different concentrations of fipronil (10-200 μg/mL), different nanoparticles amount (0.1-1 mg) at different pH (4.5-6.0) and temperature (25-75 °C). Results showed that NH2 -Fe3 O4 nanoparticles (0.1 mg) have excellent adsorption efficiency (97.06 %) at 25 °C, and pH 5.5. It also showed higher adsorption capacity towards fipronil sulfide, fipronil sulfone and fipronil desulfinyl with removal efficiencies of 92.82 %, 86.35 % and 76.24 % from aqueous solution and 97.62 %, 76.97 % and 62.65 % from eggshells, respectively. Fipronil adsorption process on NH2 -Fe3 O4 nanoparticles showed best fitting to Langmuir adsorption isotherm indicating monolayer chemical adsorption by physicochemical interactions spontaneously on homogenous surfaces. Having higher adsorption capacity and reusability NH2 -Fe3 O4 nanoparticles were shown to be effective adsorbents for removal of fipronil from aqueous solution and eggshells.

FLEA CONTROL ON PRAIRIE DOGS (CYNOMYS SPP.) WITH FIPRONIL BAIT PELLETS: POTENTIAL PLAGUE MITIGATION TOOL FOR RAPID FIELD APPLICATION AND WILDLIFE CONSERVATION.

Sylvatic plague is a widespread, primarily flea-vectored disease in western North America. Because plague is highly lethal to endangered black-footed ferrets (Mustela nigripes, BFFs) and the prairie dogs (Cynomys spp., PDs) on which BFFs depend for habitat and prey, minimizing the impacts of plague is a priority at BFF reintroduction sites. We developed a new, flour-based bait pellet containing 0.84 mg of fipronil and weighing ∼1.25 g (FipBits). We measured the degree and duration of flea control on black-tailed PDs (C. ludovicianus) in Montana and on Gunnison's PDs (C. gunnisoni) in Arizona, USA from 2018-2020. FipBits were distributed on treated plots one time at a rate of 125/ha. Fleas were virtually eliminated in Montana from 1 mo posttreatment to 1 yr later and remained substantially depressed 2 yr posttreatment. With the split colony design, we probably underestimated the degree of flea control achieved with FipBits due to crossover edge effects along the arbitrary line dividing the plots. Flea control in Arizona was significant from 1 mo posttreatment to 1 yr later, but flea abundance had recovered by 2 yr posttreatment. Flea control was evaluated from 2020-2021 in South Dakota, USA on four plots treated with three concentrations of fipronil in FipBits (0.68, 0.71, and 0.83 mg/FipBit). Fleas were essentially eliminated for 10 mo on the 0.83-mg plot and were substantially reduced on the two 0.71-mg plots. Fleas were reduced on the 0.68-mg plot, but the degree of control was less than observed on other treated plots. Impacts of plague on PDs and BFFs would probably be greatly reduced by the levels of flea control observed with FipBits. Options for expanded FipBit evaluations are being pursued for what may become a highly practical, affordable, and effective plague mitigation tool.

Comparison of the Sensitivity of Tetragonisca angustula (Apidae-Meliponini) and Apis mellifera (Apidae-Apini) to Three Insecticides (Malathion, Imidacloprid, and Fipronil) Used in Costa Rica.

The decline of insect pollinators is a significant concern within the current biodiversity crisis. The paradox between the benefits that these animals represent to humans and the evidence of human activities driving their extinction calls for the urgent protection of bees. To address the role of chemical pollution in this scenario, we assessed the acute toxicity as well as four biomarker responses (cholinesterase [ChE], glutathione S-transferase, catalase, and lipid peroxidation [LPO]) elicited by dietary 24-h exposure to three insecticides (malathion, imidacloprid, and fipronil) on the stingless neotropical bee Tetragonisca angustula and the honeybee Apis mellifera. Malathion was the most toxic substance to both species, with 48-h median lethal doses (LD50s) of 0.25 ng/bee to A. mellifera and 0.02 ng/bee to T. angustula. Fipronil was also highly toxic and presented a similar toxicity to both species, with 48-h LD50s of 0.5 ng/bee (A. mellifera) and 0.4 ng/bee (T. angustula). Imidacloprid had the lowest acute toxicity with a 48-h LD50 of 29 ng/bee for A. mellifera, whereas T. angustula tolerated exposure higher than 35 ng/bee. Apparent biomarker responses were observed in bees of both species that survived exposure to higher concentrations of malathion (ChE inhibition) and fipronil (increased LPO). Our results suggest that specific sensitivity to insecticides varies greatly among compounds and pollinator species, but the use of different representative species can facilitate the prioritization of substances regarding their risk to pollinators. Further research is necessary to better characterize the risk that pesticides represent in neotropical agricultural landscapes. Environ Toxicol Chem 2023;42:1022-1031. © 2023 SETAC.

Development of a low-dose fipronil deer feed: evaluation of efficacy against two medically important tick species parasitizing white-tailed deer (Odocoileus virginianus) under pen conditions

BackgroundOdocoileus virginianus (the white-tailed deer) is a key reproductive host for medically important tick species, including Ixodes scapularis and Amblyomma americanum. Orally administering a systemic acaricide to white-tailed deer has the potential to reduce tick reproduction, abundance and pathogen-infected tick bites. Prior studies have demonstrated considerable efficacy of a low-dose fipronil mouse bait in controlling larval I. scapularis parasitizing the pathogen reservoir, Peromyscus leucopus. No prior studies have evaluated the efficacy of a fipronil product in controlling ticks parasitizing white-tailed deer.MethodsA pen study was conducted to evaluate the efficacy of a fipronil deer feed in controlling I. scapularis and A. americanum adult ticks. Individually housed deer (n = 24) were exposed to deer feed containing 0.0025% fipronil (fipronil deer feed) for 48 h and 120 h, and a control group of deer were exposed to an untreated placebo. On post-exposure day 7 and day 21, all deer were parasitized with 20 mating pairs of feeding capsule-enclosed I. scapularis and A. americanum. Post-attachment, engorgement and mortality of ticks were recorded. The concentrations of fipronil in plasma, feces and tissues from euthanized deer were estimated using liquid chromatography-mass spectrometry.ResultsThe fipronil deer feed efficaciously controlled ticks parasitizing pen-reared white-tailed deer. Efficacy in reducing survivorship of blood-feeding female I. scapularis exceeded 90% in all instances except for when ticks parasitized 48-h treated deer at day 21 post-exposure (47.2%). Efficacy in reducing survivorship of A. americanum females exceeded 80% in all instances. In the 120-h exposure group there was 100% tick mortality at day 7 post-exposure for both tick species. A significant correlation was observed between reductions in tick survivorship and concentrations of fipronil sulfone in plasma. The results of tissue analysis suggest that a withdrawal period may be needed to allow for fipronil degradation prior to hunting season.ConclusionsThe results provide proof-of-concept for the use of a fipronil-based oral acaricide in controlling two medically important tick species infesting a key reproductive host. A field trial is necessary to confirm the efficacy and toxicology of the product in wild deer populations. Fipronil deer feed may provide a means of controlling multiple tick species parasitizing wild ruminants to be integrated into tick management programs.Graphical

Effects of exposure to sediment-associated fipronil on cardiac function of Neotropical armored catfish Hypostomus regani

Fipronil is widely used as a broad-spectrum insecticide in agriculture, urban environments, and veterinary medicine. Fipronil can enter aquatic ecosystems and spread to sediment and organic matter, representing a risk to non-target species. This study aimed to evaluate the effects of short-term (96 h) exposure to a low and realistic concentration of sediment-associated fipronil (4.2 µg.kg−1 of Regent® 800 WG) on myocardial contractility of armored catfish Hypostomus regain, a benthic fish species. Fipronil exposure induced increased inotropism and acceleration of contractile kinetics, although no alterations in the relative ventricular mass were observed. This better cardiac function was associated with an elevated expression and/or function of the Na+/Ca2+ exchanger and its marked contribution to contraction and relaxation, probably due to a stress-induced adrenergic stimulation. Ventricle strips of exposed fish also exhibited a faster relaxation and a higher cardiac pumping capacity, indicating that armored catfish were able to perform cardiac adjustments to face the exposure. However, a high energetic cost to maintain an increased cardiac performance can make fish more susceptible to other stressors, impairing developmental processes and/or survival. These findings highlight the need for regulations of emerging contaminants, such as fipronil, to ensure adequate protection of the aquatic system.

Phytotoxicity of 2,4-D and fipronil mixtures to three green manure species

Sugarcane expansion has been associated with soil contamination by agrochemicals. Pesticides can affect plant growth, and their mixture might have potentiated effects on exposed species. This research aimed to evaluate the influence of fipronil on the phytotoxicity of 2,4-D on three green manure plant species: Canavalia ensiformis, Dolichos lablab, and Lupinus albus. Plants were exposed (for 21 days, at 25 °C) to a control soil and five concentrations of each pesticide and their combinations (36 treatments, considering a full-factorial approach). Effect concentrations of 50% growth inhibition (EC50) were estimated. No phytotoxicity effects were identified when plants were exposed to different fipronil concentrations (up to 0.12 mg kg−1). All species exposed to 2,4-D showed a decrease in shoot and root length and fresh/dry biomass. L. albus and D. lablab roots showed the highest sensitivity when exposed to 2,4-D among the endpoints (EC50 = 0.02 and 0.05 mg kg−1, respectively), while C. ensiformis roots were the most tolerant (EC50 = 0.98 mg kg−1). However, the interference of fipronil on the toxicity of 2,4-D was not detected in different mixture proportions, indicating no interaction between pesticides. Residues of 2,4-D might also impair other crops’ growth, compromise productivity, and limit phytotechnologies for soil recovery.

A highly selective and sensitive europium-organic framework sensor for the fluorescence detection of fipronil in tea

A europium-based metal organic framework (Eu-TFPA-MOF) was used for the fluorescence detection of fipronil in green tea and oolong tea for the first time. The red fluorescence of Eu-TFPA-MOF could be quenched significantly by low concentration (0.24 mM) of fipronil, and the “turn off” process exhibited quick response time (2 min), high sensitivity and selectivity, low detection limits (4.4 nM) and wide linear range (0–0.15 mM). The mechanism of fluorescence quenching was mainly attributed to static quenching process and the competitive absorption of excitation energy. Besides, the spiked and recovery test indicated that Eu-TFPA-MOF could be used in the fluorescence detection of fipronil in real green tea and oolong tea sample and the process had the advantages of simple pretreatment and satisfactory recoveries (98.33–106.17 %). More importantly, a simple, portable and low-cost smartphone-assisted test strip were designed for the visual detection of fipronil in real tea samples. The detection platform will be beneficial for tea quality safety and human heath, and is expected to be applied in other agricultural product safety field.

Does Fipronil Affect on Aquatic Organisms? Physiological, Biochemical, and Histopathological Alterations of Non-Target Freshwater Mussel Species

Fipronil is widely used against insects in agriculture and ectoparasites in domestic areas and veterinary medicine. However, fipronil may influence non-target species as a result of the contamination of aquatic ecosystems. The present study aimed to investigate the acute and sublethal effects of fipronil in freshwater mussels (Unio delicatus), a non-target species, with physiological, antioxidant action mechanisms and histopathological observations. The 96-h LC50 value of fipronil was found to be 2.64 (1.45–4.56) mg/L. Sublethal concentrations were applied at 1/10 and 1/5 of 96-h LC50 as 0.264 mg/L and 0.528 mg/L for 48-h and 7-d. Haemolymph samples, digestive gland and gill tissues of mussels were taken after exposure times. While the Total Haemocyte Counts decreased in 48-h of exposure, it was only high at 0.264 mg/L fipronil-exposed for 7-d (p < 0.05). While glutathione values in digestive glands and gills were higher in the fipronil applied groups (p < 0.05), the AOPP values were only higher in the digestive glands at 7-d of exposure (p < 0.05). Moreover, fipronil caused histopathological alterations on gills and digestive glands. These things considered, the principal component analysis revealed that the most pronounced changes in the antioxidant action mechanisms were caused by the fipronil exposure. These results show that sublethal concentrations of fipronil are toxic to freshwater mussels.

Impact of Insecticides at Sublethal Concentrations on the Enzyme Activities in Adult Musca domestica L.

Nowadays, the use of pesticides is, as before, the most common way to control arthropod plant pests and the ectoparasites of animals. The sublethal effects of pesticides on insects can appear at different levels, from genetics to populations, and the study of these effects is important for a better understanding of the environmental and evolutionary patterns of pesticidal resistance. The current study aimed to assess the sublethal effects of chlorfenapyr and fipronil on the activities of detoxifying enzymes (carboxylesterase-CarE, acetylcholinesterase-AChE, glutathione-S-transferase-GST, and cytochrome P450 monooxygenase-P450) in adults Musca domestica L. The insects were exposure to insecticides by a no-choice feeding test and the enzyme activities and the AChE kinetic parameters were examined in female and male specimens at 24 h after their exposure. According to Tukey's test, the CarE activity was statistically significantly decreased by 29.63% in the females of M. domestica after an exposure to chlorfenapyr at a concentration of 0.015% when compared to the controls (p ≤ 0.05). An exposure to the sublethal concentration of fipronil (0.001%) was followed by a slightly decrease in the specific activity (33.20%, p ≤ 0.05) and the main kinetic parameters (Vmax, Km) of AChE in females in comparison with the control values. The GST and P450 activities had not significantly changed in M. domestica males and females 24 h after their exposure to chlorfenapyr and fipronil at sublethal concentrations. The results suggest that the males and females of M. domestica displayed biochemically different responses to fipronil, that is a neurotoxin, and chlorfenapyr, that is a decoupler of oxidative phosphorylation. Further research needs to be addressed to the molecular mechanisms underlying the peculiarities of the insect enzyme responses to different insecticides.

Influence of the Soil Composition on the Determination of 2,4-D and Fipronil in Environmental Samples by SLE-LC-MS/MS

The main objective of this work was to develop and validate an analytical method using solid-liquid extraction and liquid chromatography coupled with mass spectrometry in tandem (LC-MS/MS) for the simultaneous determination of the herbicide 2-(2,4-dichlorophenoxy)acetic acid (2,4-D) and the insecticide fipronil and its degradation products, fipronil sulfone and fipronil sulfide in different types of soil from Brazil (Oxisol and Entisol). Solid-liquid extraction was performed in two cycles using 20 mL of dichloromethane per cycle and sonication. The extraction efficiency of 2,4-D was more influenced by soil composition than the other compounds. The limits of quantification of the method were between 0.015 and 0.75 mg kg-1 and recovery values from 61 to 118%, with a maximum relative standard deviation (RSD) value of 4%. The method was further applied to over 500 real soil and sediment samples. 2,4-D and fipronil concentrations varied from 0.03 to 1145 µg kg-1 and 1.1 to 282 µg kg-1, respectively.

Evaluation of the susceptibility to fipronil of Rhipicephalus microplus larvae from egg masses incubated at different times of oviposition.

The objective of this work was to evaluate the susceptibility of R. microplus larvae from different oviposition times to fipronil. The LPT was performed in sextuplicate, at concentrations of 18.75, 37.5, 75, 150 and 300 µg.mL-1. The LC50 found for the egg masses incubated with +7, +14 and +21 days were respectively 105.87, 110.71 and 121.22 µg.mL-1. The larvae originating from egg masses from the same group of engorged females, incubated on different days, presented similar mortality rates compared to the evaluated fipronil concentrations, facilitating the maintenance of laboratory colonies of this tick species.

Sublethal and intergenerational effects of fipronil on Binodoxys communis larvae based on transcriptome sequencing

Fipronil is widely used in the agricultural world as an efficient phenylpyrazole insecticide to control pests. Binodoxys communis is a key parasitic natural enemy of major homopteran pests and can successfully control the population of pests such as cotton aphids. It has not yet been studied what effects would sublethal doses of fipronil have on Binodoxys communis larvae. Here, this study evaluated the effect of fipronil on Binodoxys communis larvae and analyze the transcriptome results. The results showed that LC10 (1.19 mg/L) and LC25 (1.73 mg/L) had significant negative effects on the survival rate and parasitism rate of F0 generation. Moreover, exposure to high concentrations (LC25) of fipronil still had obvious passive effect on the F1 generation of Binodoxys communis. These results indicated that sublethal doses of fipronil have malignant effects on the biological functions of parasitoids and their offspring. The results of transcriptome analysis showed that differentially expressed genes (DEGs) of Binodoxys communis after LC10 treatment are mainly related to immunity and detoxification. LC25 treatment instead resulted in changes in the expression of genes related to nutrition, energy and metabolism reactions. Seven of the identified DEGs were selected for real-time fluorescence quantitative PCR analysis. To the best of our knowledge, this is the first report to evaluate the sublethal, intergenerational, and transcriptomic side effects of fipronil on larvae of parasitic natural pest enemies. Our findings provide data to accurately assess the risk of fipronil usage on Binodoxys communis larvae, and provide important theoretical support for the comprehensive prevention and control of natural enemies and pesticides.

Pollution status and primary risk assessment of eight pesticides in coastal waters around Ishigaki Island, Japan

Ishigaki Island is a remote island in Okinawa Prefecture, Japan, with highly biodiverse ecosystems. Agriculture is one of the most important industries on Ishigaki Island; however, information about pesticide pollution on the island remains limited. Herein, we selected the eight most popular pesticides used in Okinawa Prefecture and investigated their occurrence in the coastal waters of the island; testing was performed four times from May 2020 to March 2021. In addition, we estimated the predicted no-effect concentrations (PNECs) using probabilistic approaches based on the toxicity values obtained from the ECOTOX database of the United States Environmental Protection Agency. The maximum concentrations of dichlorophenoxyacetic acid (2,4-D), bromacil, dichlorvos (DDVP), diazinon, diuron, methidathion (DMTP), fipronil, and metribuzin were 54, 46, 90, 390, 18, 3, 60, and 16 ng/L, respectively. The measured pesticide concentration levels on the island correlated with those previously reported in other areas. Pesticide concentrations were high at the mouths of rivers and decreased with increasing distance in the offshore direction until they were almost undetectable at approximately 1,000 m away. Our results suggest that agricultural runoff was the likely source of pesticides, which then entered coastal areas via rivers. Contamination was limited to the shorelines of Ishigaki Island. Further, the maximum concentrations of diazinon, diuron, and fipronil were higher than the PNECs. The maximum concentrations of DDVP and diazinon were higher than the European Union water quality standards. Our results suggest that these pesticides pose an ecological risk to the coastal environment around Ishigaki Island. This study is the first to evaluate the spatiotemporal distributions and conduct a primary ecological risk assessment of multiple pesticides in the coastal waters of Okinawa Prefecture. These results contribute to both ecosystem conservation and the agricultural industry on Ishigaki Island.

Fipronil and its metabolites in chicken feather: residue analysis, depletion study, and application analysis of pollution sources in laying hens.

A method based on a multi-mechanism impurity adsorption and ultra-performance liquid chromatography-tandem mass spectrometry was established to detect fipronil and four of its metabolites in chicken feathers. This method was successfully applied to the depletion study of fipronil in feathers of laying hens. Fipronil and two metabolites were found in feathers during treatment. Fipronil concentrations in feathers increased during medication and then regularly decreased during withdrawal, and they were still detected on the 14th day after withdrawal. High residue concentrations were also present in feathers on day 23 of the experimental period. Pollution sources of fipronil can be inferred on the basis of the residue ratio of fipronil metabolites from different pollution modes. Result shows that feathers were an effective matrix for residue monitoring and risk analysis of fipronil in animals and the environment.

Transcriptome analysis reveals differential effects of beta-cypermethrin and fipronil insecticides on detoxification mechanisms in Solenopsis invicta.

Insecticide resistance poses many challenges in insect pest control, particularly in the control of destructive pests such as red imported fire ants (Solenopsis invicta). In recent years, beta-cypermethrin and fipronil have been extensively used to manage invasive ants, but their effects on resistance development in S. invicta are still unknown. To investigate resistance development, S. invicta was collected from populations in five different cities in Guangdong, China. The results showed 105.71- and 2.98-fold higher resistance against fipronil and beta-cypermethrin, respectively, in the Guangzhou population. The enzymatic activities of acetylcholinesterase, carboxylases, and glutathione S-transferases significantly increased with increasing beta-cypermethrin and fipronil concentrations. Transcriptomic analysis revealed 117 differentially expressed genes (DEGs) in the BC-ck vs. BC-30 treatments (39 upregulated and 78 downregulated), 109 DEGs in F-ck vs. F-30 (33 upregulated and 76 downregulated), and 499 DEGs in BC-30 vs. F-30 (312 upregulated and 187 downregulated). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that DEGs associated with insecticide resistance were significantly enriched in metabolic pathways, the AMPK signaling pathway, the insulin signaling pathway, carbon metabolism, peroxisomes, fatty acid metabolism, drug metabolism enzymes and the metabolism of xenobiotics by cytochrome P450. Furthermore, we found that DEGs important for insecticide detoxification pathways were differentially regulated under both insecticide treatments in S. invicta. Comprehensive transcriptomic data confirmed that detoxification enzymes play a significant role in insecticide detoxification and resistance development in S. invicta in Guangdong Province. Numerous identified insecticide-related genes, GO terms, and KEGG pathways indicated the resistance of S. invicta workers to both insecticides. Importantly, this transcriptome profile variability serves as a starting point for future research on insecticide risk evaluation and the molecular mechanism of insecticide detoxification in invasive red imported fire ants.

Label-Free Aptasensor for Detection of Fipronil Based on Black Phosphorus Nanosheets.

A label-free fipronil aptasensor was built based on Polylysine-black phosphorus nanosheets composition (PLL-BPNSs) and Au nanoparticles (AuNPs). A PLL-BP modified glassy carbon electrode (GCE) was fabricated by combining BP NSs and PLL, which included a considerable quantity of -NH2. Au nanoparticles (AuNPs) were placed onto the GCE, and PLL-BPNSs bonded to Au NPs firmly by assembling. The thiolated primers were then added and fixed using an S-Au bond, and competitive binding of the fipronil aptamer was utilized for fipronil quantitative assessment. The sensor’s performance was evaluated using differential pulse voltammetry (DPV) method. The linear equation is ΔI (μA) = 13.04 logC + 22.35, while linear correlation coefficient R2 is 0.998, and detection limit is 74 pg/mL (0.17 nM) when the concentration of fipronil is 0.1 ng/mL–10 μg/mL. This aptasensor can apply to quantitative detection of fipronil.