Neonicotinoid insecticide toxicology: mechanisms of selective action

Acetamiprid-induced pulmonary toxicity via oxidative stress, epithelial-mesenchymal transition, apoptosis, and extracellular matrix accumulation in human lung epithelial cells and fibroblasts: Protective role of heat-killed Lactobacilli

Acetamiprid (ACE) is a neonicotinoid insecticide with widespread global application, resulting in persistent human exposure. The current research examined the toxicological implications of ACE exposure on human lung fibroblasts (MRC-5 cells) and bronchial epithelial cells (BEAS-2B cells). The following implications were explored: oxidative stress, epithelial-mesenchymal transition, apoptosis, cellular proliferation, and extracellular matrix accumulation. The prospective protective properties of heat-killed Lactobacillus fermentum and Lactobacillus delbrueckii (HKL) were further studied. The 14-day exposure to ACE at 4 μM triggered oxidative stress and inflammation. ACE promoted epithelial-mesenchymal transition, as evidenced by the decline of protein and mRNA abundances of E-cadherin alongside increased protein and mRNA quantities of α-SMA and N-cadherin in BEAS-2B cells. Additionally, it elicited apoptosis in BEAS-2B cells and stimulated the cellular growth of MRC-5 cells. The TGF-β1/Smad pathway was activated upon ACE exposure, leading to the accumulation of extracellular matrix. HKL demonstrated antioxidant, anti-apoptotic, anti-proliferative, and anti-fibrotic properties, mitigating ACE-induced toxicity. Our findings delineate the molecular mechanisms underlying epithelial-mesenchymal transition, inflammation, oxidative stress, and extracellular matrix accumulation in ACE-induced pulmonary fibrosis, which provides new insights into pulmonary injury. Additionally, this investigation would offer us an approach to mitigate lung deterioration induced by ACE through utilizing heat-killed probiotic supplementation.

Subacute genotoxicity of acetamiprid in somatic cells of Swiss albino male mice

Pesticides are applied to plants all over the world to boost food production and lower the spread of diseases carried by insects. Exposure to the pesticides may cause genotoxic effects on target and non-target organisms, including humans. In agriculture, acetamiprid (ACE), a neonicotinoid insecticide, is frequently applied either alone or in conjunction with other pesticides. A combined approach employing the micronucleus test (MNT) and chromosomal aberrations (CAs) assay was used to evaluate the genotoxic effects of acetamiprid in the bone marrow of male Swiss albino mice. Acetamiprid was administered i.p. daily at 4.6 and 2.3 mg/kg/day along with 3% gum acacia as a negative control for 30 days. ACE treatment resulted in a small dose dependent increase in the frequencies of micronuclei per cell (0.28 ± 0.04, 0.38 ± 0.03, and 0.45 ± 0.02 for the control, 2.3 and 4.6 mg/kg b.wt. groups, respectively) and chromosomal aberrations (3.67 ± 0.61, 5.00 ± 0.45, and 7.00 ± 1.43 for the control, 2.3 and 4.6 mg/kg b.wt. groups, respectively) in bone marrow cells, but no significant differences were observed between these data sets. In conclusion, daily i.p. exposure of ACE @ 2.3 and 4.6 mg/kg b.wt. for 30 days did not produce significant genotoxic effects in the somatic cells of Swiss albino male mice.

Biochemical targets of chick embryos affected by sub-lethal concentrations of lambda-cyhalothrin and imidacloprid

The insecticides Lambda-cyhalothrin (LCT) and imidacloprid (IMD) are extensively utilized in Egyptian agriculture. Embryonic chicken is a readily accessible model organism commonly employed in various studies. Eggs of (Gallus Gallus) chicken were immersed in an aqueous solution of two sub-lethal concentrations (0.375 and 0.0375 mg/L for LCT; 0.05 and 0.005 mg/L for IMD) for 30  sec on the fourth day of incubation of chick embryos. Significant reductions of acetylcholinesterase (AChE) activity of brain 18- and 21-day chicks were observed in the groups treated with LCT and IMD dependent on concentrations. There were significant changes (reduction or enhancement) in serum activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) by LCT and IMD at the used concentrations, while non-significant stimulation in the AST/ALT ratio (AAR) was found. In 18th - day embryos, the activities of glutathione S-transferase (GST) and acid phosphatase (ACP) were not significantly changed by LCT but were significantly increased by IMD. Liver alkaline phosphatase (ALP) activity showed no significant change except IMD at 0.05 mg/L. However, serum enzyme activity was significantly reduced in all groups. In addition, the tested insecticides caused notable increases in the creatinine and total protein content. The protein profile; proteins separation with sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed an increase in four bands that are consistent with the results of the biomarkers level. Findings indicate that even the pesticide's low concentrations are not safe and may lead to severe damage to the embryos and may lead to significant harm or developmental disruption in the embryos.

Insights into the mobility and bacterial hosts of antibiotic resistance genes under dinotefuran selection pressure in aerobic granular sludge based on metagenomic binning and functional modules

Dinotefuran (DIN) is toxic to non-target organisms and accelerates the evolution of antibiotic resistance, which poses a problem for the stable operation of the activated sludge process in wastewater treatment plants (WWTPs). However, the emergence and the transfer mechanism of antibiotic resistance genes (ARGs) in activated sludge systems under DIN stress remains unclear. Thus, in the study, the potential impact of DIN on ARGs and virulence factor genes (VFGs) in aerobic granular sludge (AGS) was investigated in depth using metagenomic binning and functional modules. It was found that DIN stress increased the total abundance of ARGs, mobile genetic elements (MGEs), and VFGs in the AGS system, with the highest abundance of fabG (4.6%), tnpA (55.6%) and LPS (39.0%), respectively. The proliferation of the enteric pathogens Salmonella enterica and Escherichia coli in the system indicates that DIN induces exposure of harmless bacteria to the infected environment. The genera Nitrospira (1169 ARG subtypes) and Dechloromonas (663 ARG subtypes) were identified as the potentially antibiotic-resistant bacteria carrying the most ARGs and MGEs in the metagenome-assembled genomes. Co-localization patterns of some ARGs, MGEs, and the SOS response-related gene lexA were observed on metagenome-assembled contigs under high levels of DIN exposure, suggesting DIN stimulated ROS production (101.8% increase over control), altered cell membrane permeability, and increased the potential for horizontal gene transfer (HGT). Furthermore, the DNA damage caused by DIN in AGS led to the activation of the antioxidant system and the SOS repair response, which in turn promoted the expression of the type IV secretion system and HGT through the flagellar channel. This study extends the previously unappreciated DIN understanding of the spread and associated risks of ARGs and VFGs in the AGS system of WWTPs. It elucidates how DIN facilitates HGT, offering a scientific basis for controlling emerging contaminant-induced resistance.

Automated video-tracking analysis of Agriotes obscurus wireworm behaviour before, during and after contact with thiamethoxam- and imidacloprid-treated wheat seeds

Limited studies have highlighted the importance of incorporating behavioural assessments into insecticide efficacy evaluations for wireworm pest control. "For this study, video tracking technology combined with a soil bioassay arena was employed to analyse the behaviour of Agriotes obscurus wireworms before, during, and after exposure to wheat seeds treated with the neonicotinoid insecticides thiamethoxam and imidacloprid at field-relevant concentrations. The analysis identified a set of behavioural key metrics for assessing the effects of these insecticides on wireworms. The results showed that these insecticides exhibited neutral attractancy towards wireworms. A brief period of feeding followed by rapid intoxication minimised damage to seeds. Furthermore, the wireworms demonstrated a specific form of behavioural resistance to neonicotinoids that did not rely on sensory input. In these insects, the rapid speed of intoxication, accompanied by drastic changes in behaviour, ensured that they received a sublethal rather than lethal dose of the insecticide. The wireworms fully recovered from all behavioural abnormalities within a week, and none died within 20 days following the exposure. In conclusion, this video tracking method provides a rapid and efficient means of assessing insecticides intended for wireworm management, offering valuable insights prior to more resource-intensive and costly field trials.

Imidacloprid and amitraz differentially alter antioxidant enzymes in honeybee (Apis mellifera) hemocytes when exposed to microbial pathogen-associated molecular patterns

Honeybees (Apis mellifera) are increasingly exposed to pesticides and microbial stressors, yet their combined effects on immune defenses remain unclear. Exposure to the neonicotinoid imidacloprid and the acaricide amitraz, alone and in combination, alters antioxidant enzyme activity in hemocytes when challenged with bacterial components such as lipopolysaccharide and peptidoglycan or the fungal-derived molecule zymosan A. The combination of pesticides with zymosan A synergistically suppresses superoxide dismutase and glutathione-S-transferase activity, while catalase activity remains unchanged. In contrast, lipopolysaccharide counteracts pesticide-induced oxidative stress, suggesting immune-pathway-specific modulation. The heightened vulnerability of honeybees to fungal-associated immune challenges in pesticide-contaminated environments compromises their ability to detoxify harmful substances and respond to infections. Such approaches that include comparison of different microbial interactions, pesticide cocktails, and immunity are needed. Understanding these interactions is essential for improving pesticide regulations and pollinator conservation efforts in the face of increasing environmental stressors.

Exploring the larvicidal and pupicidal activities of new functionalized pyridines against Culex pipiens L. referring to molecular docking and SAR studies

Pesticides are intensively employed to manage pests, but they pose a great challenge, developing pesticide resistance. So, searching for novel chemical structures is crucial to overcoming insecticide resistance. Herein, a new functionalized pyridine derivative 4 was effectively constructed in a one-step reaction through reacting four components, including piperonal, ethyl cyanoacetate, 2-acetylthiophene, and ammonium acetate, under ultrasonic conditions. Treatment of the derivative 5 with hydrazine hydrate in ethanol afforded the acetohydrazide derivative 8 that was utilized as a key precursor for the synthesis of Schiff's bases and other nicotinonitriles. Moreover, new acetohydrazone derivatives (19-21) were furnished by the reaction of 8 with isatin, n-vinylpyrrolididone, and galactose, respectively. The data obtained from the spectral measurements was the basis for elucidating the structures of the new derivatives. The larvicidal and pupicidal potencies of the synthesized thienyl pyridine derivatives were assessed against Culex pipiens L., and most exhibited moderate to good activity. The larvae were more susceptible to 17, 19, 6 and 13 with LC50 of 1.57, 1.91, 2.36 and 2.90 ppm, respectively, while pupae were less susceptible with LC50 of 4.17, 5.03, 6.16 and 7.45 ppm, respectively. The various functional groups connected to the pyridine ring led to variations in the toxicity of synthesized compounds, which were clarified through the SAR study. At the same time, a molecular docking study was performed to demonstrate the compound's mode of action and the effect of inserted moieties on binding with the nicotinic acetylcholine receptors (nAChRs). Collectively, the results imply that the thienyl pyridine derivatives could be used as mosquitocidal agents against C. pipiens larvae and pupae.

Significant variations in tolerance to clothianidin and pirimiphos-methyl in Anopheles gambiae and Anopheles funestus populations during a dramatic malaria resurgence despite sustained indoor residual spraying in Uganda

A dramatic malaria resurgence occurred in areas of Uganda between 2020 and 2022 coincident with the switch to clothianidin-based formulations for indoor residual spraying. During the resurgence, Anopheles funestus numbers increased but when an alternative insecticide, pirimiphos methyl, was reintroduced in 2023, both malaria cases and An. funestus mosquito density fell. In this study, we investigated possible causes of the resurgence by assessing; 1) whether sufficient quantities of insecticide were sprayed; 2) the residual insecticide bioefficacy against wild mosquitoes and; 3) the insecticide susceptibility of vector populations using standard test tube assays and wall cone assays. In 2023, after adjusting for extraction efficiency, 70-80% of the houses had optimal residual concentrations of insecticides (clothianidin >0.3g/m2; pirimiphos methyl >0.5g/m2) with significant variations between sampling rounds and wall types. Mud walls had the lowest residual concentration of insecticides, and the lowest observed mortality in wall cone assays, compared to fired bricks with plaster/cement/paint. In the studies of residual bio efficacy, by World Health Organization (WHO) definitions, An. funestus showed resistance to clothianidin (<80% mortality) up to 11 months and susceptibility to pirimiphos methyl (>90% mortality) when exposed to wall surfaces up to 7 months post-spray. In WHO tube tests, variations were observed in susceptibility to clothianidin in An. funestus populations using dose- and time-response assays (80-98% mortality). In 2022, An. gambiae was largely susceptible to the clothianidin-based formulation Sumishield (85-90% mortality) although the levels dropped slightly in 2023 (60-85% mortality) mainly in mud and pole houses. In contrast, An. gambiae was mildly susceptible to the pirimiphos methyl-based formulation Actellic (~80% mortality) and time response assays showed An. gambiae populations had very low knockdown and mortality at lower exposure time compared to An. funestus. Regression models showed a positive association between residual insecticide concentration (RIC) and mortality in houses sprayed with Sumishield but not Actellic houses. Despite the possible variations observed in spray operations, the study revealed that An. funestus exhibited a higher tolerance to clothianidin-based formulations compared to An. gambiae, and this might have driven the malaria resurgence observed in Uganda. However, there are signals of An. gambiae resistance to pirimiphos-methyl which will require further investigation and monitoring.

Bees as environmental and toxicological bioindicators in the light of pesticide non-targeted exposure

Pesticides have a significant impact on the environment, harming valuable non-target organisms like bees. Honeybees, in particular, are ideal bioindicators of pesticide exposure due to extensive research on how pesticides affect their behavior, immunity, development, biomolecules, and detoxification. However, wild pollinators are less studied in terms of pesticide exposure, and their inclusion is essential for a comprehensive risk assessment. Additionally, food chain organisms, such as the Asian hornet, could serve as indicators of pesticide bioaccumulation. Addressing gaps in honeybee toxicology, understanding the limitations, and exploring the role of wild pollinators and insects as complementary indicators, along with advancements in risk assessment methodologies, could enhance predictive models. These models would help anticipate environmental pesticide impacts while reducing the need for costly, time-consuming research.

Protective effect of Urtica urens L. against nephrotoxicity induced by imidacloprid in rats

Imidacloprid (IMI) has been known to cause nephrotoxicity. Some reports claim that Urtica urens L. (U. urens) can reduce toxicity. The present study was undertaken to evaluate the protective effect of U. urens against this toxicity. Rats were divided into control group, three groups treated with IMI at 50, 200, or 300 mg/kg/day and three groups injected with IMI (50, 200, or 300 mg/kg/day) + 100 mg/kg/day of U. urens, for 60 days. Urine and blood samples were collected for dosage of biochemical levels. Kidneys were removed for oxidative stress and histological examination. IMI caused acute renal injury and increased the levels of biochemical and tissue MDA. It also decreased the levels of antioxidant enzyme activities. Urtica urens injection improved the histological and all biochemical parameters. IMI induced an acute renal injury accompanied with disturbance of oxidant status U. urens injection provided a significant protection thanks to antioxidant properties.

Diffusive gradients in thin-films (DGT) for in situ measurement of neonicotinoid insecticides (NNIs) in waters

Neonicotinoid insecticides (NNIs) are among the most widely-used insecticides, although their threat to non-target organisms has attracted attention in recent years. In this study, a diffusive gradient in thin-films (DGT) passive sampling technique was developed for in situ monitoring of time-weighted average (TWA) concentrations of NNIs in groundwater and wastewater. Systematic studies demonstrated that DGT with HLB as binding gels (HLB-DGT) is suitable for quantitative sampling of NNIs under a wide range of conditions, independent of pH (5-9.5), ionic strength (0.001-0.5 M) and dissolved organic matter (0-10 mg/L). The HLB-DGT performance was also independent of the typical groundwater ionic environments. The thicknesses of in-situ measured diffusive boundary layer were 0.35 and 0.25 mm in the groundwater and effluent, respectively. HLB-DGT can provide TWA concentrations over 14-18 days' deployment with linear uptake in both groundwater and wastewater. Concentrations and occurrence patterns of NNIs obtained by HLB-DGT were consistent with those measured from grab samples. The median TWA concentration of NNIs was 4.42 ng/L in water from the largest urban lake of China (the Tangxun Lake) in winter, with wastewater discharge being the main potential source. The reliability and stability of the HLB-DGT for measuring NNIs in the groundwater and surface water were confirmed and can be used to improve understanding of the occurrence and fate of NNIs in aquatic environment.

Indoor Residual Spraying With Fludora Fusion for Malaria Control in Pyrethroid-Resistant Areas of Gujarat, India: A Community-Randomized Trial

Background: The development of insecticide resistance in malaria vectors has necessitated a need to evaluate new insecticide molecules with different modes of action. In the present study, Fludora Fusion 562.5 WP-SB (clothianidin 50% + deltamethrin 6.25% AI/kg) was evaluated for its efficacy and residual action for the control of pyrethroid-resistant malaria vector, Anopheles culicifacies (Diptera: Culicidae), during May 2017 to February 2018 in Gujarat state, India. Methods: Fludora Fusion at the dose of 225 mg AI/m2 and bendiocarb at a dose of 400 mg AI/m2 as a positive control were sprayed in 5 villages each in districts of Kheda, Vadodara, and Panchmahal. The persistence of their efficacy on different local surfaces was determined against An. culicifacies. Entomological indices such as indoor resting density, human landing collections, pyrethrum spray collections, and exit trap collections were monitored to assess the impact of spraying. Results: The observed residual action of Fludora Fusion on mud and cement surfaces was for 6 months and bendiocarb for 3-4 months on both surfaces. Indoor resting densities and parous rate of An. culicifacies were significantly lower in houses sprayed with Fludora Fusion compared to bendiocarb-sprayed houses. Daily entomological inoculation rate (EIR) declined from 1.275 during prespray period to 0.5225 in the Fludora Fusion arm and 0.3802 in the Ficam arm in postspray period, indicating a reduction in the malaria transmission potential of An. culicifacies in both arms. Conclusion: Based on the residual action of the Fludora Fusion on most common sprayed surfaces and its effects on the elements of vectorial capacity, Fludora Fusion at 225 mg/m2 dose was found effective for more than 6 months and could be a potential option for the control of resistant mosquito vectors.

Exposure of Apis mellifera (Hymenoptera: Apidae) colonies to imidacloprid impairs larval development, promotes oxidative stress in pupae, and induces changes in the midgut of adult bees

Bees are essential pollinators that contribute to maintaining biodiversity and increasing agricultural production. However, by foraging on agricultural crops, bees may become contaminated with compounds used for pest control. In this study, we exposed bee (Apis mellifera L.) colonies to the insecticide imidacloprid (IMD) under field conditions to assess the occurrence of oxidative stress in larvae and pupae and investigate morphological changes in the fat body and midgut of larvae and midgut of adult bees. The apiary area was divided into three groups: control, commercial formulation containing IMD (Evidence® 700WG) (IMDCF), and IMD active ingredient (Sigma-Aldrich) (IMDAI). Treatment groups were fed syrup containing 1 µg L-1 IMD, whereas the control group was fed syrup only. Compared with the control, larvae exposed to IMDCF or IMDAI for 42 days exhibited morphological changes in the external body, midgut, and fat body. The midgut of adult bees contaminated with IMDCF showed only structural remnants of the peritrophic membrane and absence of regenerative cell nests. Oxidative stress analyses revealed that IMDCF-exposed larvae had higher nitrite and carbonylated protein contents and lower catalase and superoxide dismutase activity than control individuals. In pupae, IMDAI decreased catalase activity while increasing superoxide dismutase activity. These findings indicate that IMD has the potential to significantly impact the development of bees and their colonies by disrupting vital organs responsible for normal physiological functioning and overall activities of individuals. Oxidative stress, which was detected at different stages of bee development, may induce lipid, protein, and DNA oxidation, leading to cell death.

Temporal evolution of insecticide resistance and bionomics in Anopheles funestus, a key malaria vector in Uganda

Insecticide resistance escalation is decreasing the efficacy of vector control tools. Monitoring vector resistance is paramount in order to understand its evolution and devise effective counter-solutions. In this study, we monitored insecticide resistance patterns, vector population bionomics and genetic variants associated with resistance over 3 years from 2021 to 2023 in Uganda. Anopheles funestus s.s was the predominant species in Mayuge but with evidence of hybridization with other species of the An. funestus group. Sporozoite infection rates were relatively very high with a peak of 20.41% in March 2022. Intense pyrethroid resistance was seen against pyrethroids up to 10-times the diagnostic concentration but partial recovery of susceptibility in PBO synergistic assays. Among bednets, only PBO-based nets (PermaNet 3.0 Top and Olyset Plus) and chlorfenapyr-based net (Interceptor G2) had high mortality rates. Mosquitoes were fully susceptible to chlorfenapyr and organophosphates, moderately resistant to clothianidin and resistant to carbamates. The allele frequency of key P450, CYP9K1, resistance marker was constantly very high but that for CYP6P9A/b were very low. Interestingly, we report the first detection of resistance alleles for Ace1 gene (RS =  ~ 13%) and Rdl gene (RS =  ~ 21%, RR =  ~ 4%) in Uganda. The qRT-PCR revealed that Cytochrome P450s CYP9K1, CYP6P9A, CYP6P9b, CYP6P5 and CYP6M7 were consistently upregulated while a glutathione-S-transferase gene (GSTE2) showed low expression. Our study shows the complexity of insecticide resistance patterns and underlying mechanisms, hence constant and consistent spatial and temporal monitoring is crucial to rapidly detect changing resistance profiles which is key in informing deployment of counter interventions.

Occurrence and fate of five representative neonicotinoid insecticides across different wastewater treatment plants and the impact on receiving water bodies

Neonicotinoids (NEOs), despite their widespread use as insecticides, exhibit a notable knowledge deficit in regards to their presence in wastewater treatment plants (WWTPs) and their surrounding environments. This study delves into the presence and disposition of 5 NEOs: Thiamethoxam (THM), Clothianidin (CLO), Imidacloprid (IMD), Acetamiprid (ACE), and Thiacloprid (THA) across 3 domestic WWTPs and their receiving waters. Notably, THM, CLO, and ACE were consistently detected in all water and sludge samples, with THM emerging as the most abundant compound in both influent and effluent. Among the 3 WWTPs, WWTP 2, employing a fine bubble oxidation process, achieved the highest removal efficiency, surpassing 68%, in contrast to WWTP 1 (CAST) at 37% and WWTP 3 (A/A/O) at 7%. Biodegradation played a pivotal role in NEO removal, accounting for 36.7% and 68.2% of the total removal in WWTP 1 and WWTP 2, respectively. Surprisingly, in WWTP 3, biotransformation process inadvertently increased ACE and CLO concentrations by approximately 4.1% and 4.5%, respectively. The total NEO concentration in the receiving surface waters ranged from 72.7 to 155.5 ng/L, while sediment concentrations were significantly lower, spanning between 0.10 and 1.53 ng/g. WWTPs serve as both a removal and concentration point for NEOs, thereby significantly influencing their transportation. Additionally, the concentration of most NEOs in the receiving waters progressively increased from upstream to downstream, highlighting the substantial impact of WWTP discharges on natural water environments. This research offers valuable insights into NEO pollution surrounding WWTPs in the Pearl River Delta, ultimately aiding in pollution control and environmental protection decisions.

Human acute poisoning incidents associated with neonicotinoid pesticides in the U.S. Incident Data System (IDS) database from 2018-2022 - frequency and severity show public health risks, regulatory failures

BACKGROUND

Neonicotinoid pesticides ('neonics') - imidacloprid, thiamethoxam, clothianidin, acetamiprid, dinotefuran-are the most widely used class of insecticides in the world. They have a neurotoxic mechanism of action, similar to nicotine. They are detected in food, waterways, tap water, and breast milk.

METHODS

We make use of the non-occupational human pesticide poisoning reports in the U.S. Environmental Protection Agency (EPA) online Incident Data System (IDS). The data set contains individual incidents, and incidents aggregated and submitted in bulk to EPA. IDS reports are predominantly self-reported information of varying and often low level of detail and are not routinely validated or verified by EPA.

RESULTS

We reviewed 842 non-occupational human poisoning incidents associated with neonics in the IDS from 2018 through 2022. There are four human fatality reports, two associated with clothianidin and two with acetamiprid. Major illnesses such as seizures were reported in several cases, including with dinotefuran cockroach bait product, and an imidacloprid lawn product. Moderate poisonings make up 88% of the total poisonings (740 of 842), with most of those associated with imidacloprid (547 incidents) or dinotefuran (102 incidents). Common reported symptoms classified as moderate often included two or more of the following: headaches; dizziness; lethargy; eye or throat irritation; skin itching and rash; chemical burns and skin peeling; face swelling; muscle weakness or tremors; vomiting; diarrhea; pain and tightness in chest; open sores; and general pain. These incidents stem mainly from residential uses, such as lawn and garden insect repellents, home pest treatments for bed bugs or roaches, and products used to treat pets for fleas and ticks.

CONCLUSION

Given the evidence of neurotoxicity, EPA should use its legal authority to cancel unsafe products and unnecessary uses - including from seed treatments, and residential pet and lawncare products - to prevent further human suffering.

Unveiling the physical, behavioural, and biochemical effects of clothianidin on a non-target organism, Drosophila melanogaster

Clothianidin is a novel neonicotinoid pesticide globally used in agriculture to enhance crop production. However, unintentional exposure to clothianidin via contaminated environmental matrices and food products can be detrimental to non-target organisms, including humans. Hence, to unravel the potential health risks at organismal and sub-organismal levels, first instar larvae of a non-target organism, Drosophila melanogaster, were exposed to sub-lethal concentrations (0.05 to 0.1 μg/mL) of clothianidin till their third instar stage (chronic exposure). Larvae from the control and clothianidin-exposed groups were examined for their body weight, physical activity, behaviour, and enzymatic activities using in vivo and molecular docking approaches. Results have suggested that clothianidin at sub-lethal concentrations reduces body weight and physical fitness of D. melanogaster. Interestingly, AChE activity in larvae was reduced by 35 % and 41.13 % following exposure to 0.07 and 0.1 μg/mL of clothianidin, respectively. Further, the activity of mitoferrin, a major importer of iron inside the mitochondrial matrix and malate dehydrogenase, an integral component of the TCA cycle, were down-regulated by 58 % and 45.93 %, respectively, at 0.1 μg/mL clothianidin. Additionally, the activities of glucose 6-phosphate dehydrogenase, a vital enzyme of the pentose phosphate pathway and angiotensin-converting enzyme, responsible for maintaining optimum body physiology, were significantly declined by 43.58 % and 57.63 % at 0.1 μg/mL concentration of clothianidin. Binding affinity analyses have revealed that clothianidin can potentially bind with these enzymes using varying numbers of hydrogen bonds and other hydrophobic interactions to subvert their catalytic functions. Therefore, results of the present study equivocally suggest that chronic exposure to clothianidin, even at low concentrations, can disturb the physical, behavioural, and enzymatic activities of non-target organisms.

Urban sewage discharge of neonicotinoids and their transformation products threatens aquatic organisms

Neonicotinoid insecticides (NEOs) are frequently used for urban landscape management and vector control, and undergo various transformation processes when release into urban environments. The discharges of NEOs and their transformation products (TPs) from urban sewer networks may pose serious threats to freshwater ecosystem integrity. However, TPs of NEOs present in municipal wastewater treatment plants (MWWTPs) and their associated risks to aquatic organisms are largely unknown. Here, we investigate NEOs and their TPs in 28 MWWTPs of six Chinese cities. Eleven NEOs and 33 TPs were identified, and 17 TPs were firstly detected in environmental medium. Considerable concentrations of NEOs and their TPs (17.0-1543 ng/L) were measured in the effluents, and two NEOs exceeded the ecological quality reference values in 32.1 % (for clothianidin) and 78.6 % (for imidacloprid) of the effluents. Simultaneously, 12 TPs had a higher regulatory priority than the corresponding NEOs in at least one aquatic organism using a toxicological priority index. Furthermore, 79.5 % of NEOs and their TPs exhibited high persistence and mobility, and thus these compounds could readily spread over long distances in aquatic environment. This study highlights that the input of NEOs and their TPs from treated wastewater into aquatic ecosystem should be regulated to mitigate the ecological risks.

Pharmacology and molecular modeling studies of sulfoxaflor, flupyradifurone and neonicotinoids on the human neuronal α7 nicotinic acetylcholine receptor

We conducted electrophysiological and molecular docking studies using a heterologous expression system (Xenopus oocytes) to compare the effects of four neonicotinoids (acetamiprid, imidacloprid, clothianidin and thiamethoxam), one sulfoximine, (sulfoxaflor), and one butenolide (flupyradifurone), on human α7 neuronal nicotinic acetylcholine receptors (nAChRs). All neonicotinoids (except thiamethoxam), as well as the recently introduced nAChR competitive modulators, flupyradifurone and sulfoxaflor, appear to be weaker agonists than acetylcholine. Two mutations in loop C (E211N and E211P) and one mutation in loop D (Q79K), known to be involved in the binding properties of neonicotinoids were introduced to the α7 wild type. Interestingly, the acetylcholine and nicotine-evoked activation was not modified in human α7 mutated receptors, but the net charge was enhanced for clothianidin and imidacloprid, respectively. Flupyradifurone responses strongly increased under the Q79K mutation. The molecular docking investigations demonstrated that the orientations and interactions of the ligands considered were in accordance with those observed experimentally. Specifically, the charged fragments of acetylcholine and nicotine, used as reference ligands, and their neonicotinoid homologs were found to be surrounded by aromatic residues, with key interactions with Trp171 and Y210. Furthermore, the molecular docking investigations predicted the water-mediated interaction between the carbonyl oxygen of acetylcholine and the Nsp2 nitrogen of the pyridine ring for nicotine (as well as for the majority of the corresponding neonicotinoid fragments) and main chain NH of L141. The docking scores, extending over a significant range of 6 kcal/mol, showed that most neonicotinoids were poorly stabilized in the α7 nAChR compared to acetylcholine, except sulfoxaflor.

Sensitivity Variations in Developmental Toxicity of Imidacloprid to Zebrafish Embryos at Different Neurodevelopmental Stages

Neonicotinoids are ubiquitous in global surface waters and pose a significant risk to aquatic organisms. However, information is lacking on the variations in sensitivity of organisms at different developmental stages to the neurotoxic neonicotinoids. We established a spectrum of toxicity to zebrafish embryos at four neurodevelopmental stages (1, 3, 6, and 8 h post fertilization [hpf]) and dechorionated embryos at 6 hpf based on external and internal exposure to imidacloprid as a representative neonicotinoid. Embryos at the gastrula stage (6 and 8 hpf) were more sensitive to imidacloprid than embryos at earlier developmental stages. Dechorionated embryos were more sensitive to imidacloprid than embryos with a chorion, suggesting that the chorion offers protection against pollutants. Nine sublethal effects were induced by imidacloprid exposure, among which uninflated swim bladder (USB) was the most sensitive. Water depth and air availability in the exposure chambers were critical factors influencing the occurrence of USB in zebrafish larvae. Internal residues of metabolites accounted for <10% of imidacloprid, indicating that imidacloprid was metabolized in a limited fashion in the embryos. In addition, acute toxicity of the main metabolite 5-hydroxy-imidacloprid was significantly lower than that of imidacloprid, indicating that the observed toxicity in embryos exposed to imidacloprid was mainly induced by the parent compound. Our research offers a fresh perspective on choosing the initial exposure time in zebrafish embryo toxicity tests, particularly for neurotoxicants. Environ Toxicol Chem 2024;43:2398-2408. © 2024 SETAC.

Impact of Sublethal Insecticides Exposure on Vespa magnifica: Insights from Physiological and Transcriptomic Analyses

Insecticides are widely used to boost crop yields, but their effects on non-target insects like Vespa magnifica are still poorly understood. Despite its ecological and economic significance, Vespa magnifica has been largely neglected in risk assessments. This study employed physiological, biochemical, and transcriptomic analyses to investigate the impact of sublethal concentrations of thiamethoxam, avermectin, chlorfenapyr, and β-cypermethrin on Vespa magnifica. Although larval survival rates remained unchanged, both pupation and fledge rates were significantly reduced. Enzymatic assays indicated an upregulation of superoxide dismutase and catalase activity alongside a suppression of peroxidase under insecticide stress. Transcriptomic analysis revealed increased adenosine triphosphate-related processes and mitochondrial electron transport activity, suggesting elevated energy expenditure to counter insecticide exposure, potentially impairing essential functions like flight, hunting, and immune response. The enrichment of pathways such as glycolysis, hypoxia-inducible factor signaling, and cholinergic synaptic metabolism under insecticide stress highlights the complexity of the molecular response with notable effects on learning, memory, and detoxification processes. These findings underscore the broader ecological risks of insecticide exposure to non-target insects and highlight the need for further research into the long-term effects of newer insecticides along with the development of strategies to safeguard beneficial insect populations.

Molecular Recognition Properties of Nicotinic Ligands Determining Selectivity Between Insect and Mammalian Receptors

This investigation defines the roles of various amino acids, neighboring key conserved amino acids in loops C and D of the nicotinic acetylcholine (ACh) receptor (nAChR), in the selective molecular recognition of nicotinic ligands with diverse pharmacophores using Aplysia californica ACh binding protein Y55W (Ac-AChBP) mutants (+Q57R; + Q57R+S189 V; + Q57R+S189E; + Q57T; + Q57T+S189 V; + Q57T+S189E) and Lymnaea stagnalis AChBP (Ls-AChBP) mutants (Q55T; Q55T+S186E; Q55R) as insect and mammalian nAChR structural surrogates, respectively. N-nitro/cyanoimine insecticides show high affinity to four Ac-AChBPs containing Arg57 or Thr57 and Ser189 or Val189, except for those with Glu189. Pyrazinoyl compound selectively interacts with the three Ac-AChBPs containing Arg57 and Ser189, Val189, or Glu189. Cationic ligands prefer three Ac-AChBPs with Thr57 and Ser189, Val189, or Glu189 and two Ls-AChBPs providing Thr55 ± Glu186 over the four Ac- and Ls-AChBPs with Arg57/55. Accordingly, loop C contributes to N-nitro/cyanoimine insecticide action, and loop D controls the affinity of the pyrazinoyl or cationic ligand.

Achievements and perspectives of synthetic biology in botanical insecticides

Botanical insecticides are the origin of all insecticidal compounds. They have been widely used to control pests in crops for a long time. Currently, the commercial production of botanical insecticides extracted from plants is limited because of insufficient raw material supply. Synthetic biology is a promising and effective approach for addressing the current problems of the production of botanical insecticides. It is an emerging biological research hotspot in the field of botanical insecticides. However, the biosynthetic pathways of many botanical insecticides are not completely elucidated. On the other hand, the cytotoxicity of botanical pesticides and low efficiency of these biosynthetic enzymes in new hosts make it still challenging for their heterologous production. In the present review, we summarized the recent developments in the heterologous production of botanical insecticides, analyzed the current challenges, and discussed the feasible production strategies, focusing on elucidating biosynthetic pathways, enzyme engineering, host engineering, and cytotoxicity engineering. Looking to the future, synthetic biology promises to further advance heterologous production of more botanical pesticides.

Cytotoxicity induced by three commercial neonicotinoid insecticide formulations in differentiated human neuroblastoma SH-SY5Y cells

Background

Neonicotinoid insecticides are used worldwide for crop protection. They act as agonists at postsynaptic nicotinic acetylcholine receptors (nAChRs), disrupting normal neurotransmission in target insects. Human exposure is high due to the widespread use of neonicotinoids and their residues in food. This study aimed to evaluate the in vitro neurotoxicity of three neonicotinoid commercial formulations Much 600 FS® (imidacloprid 600 g L-1), Evidence 700 WG® (imidacloprid 700 g kg-1), and Actara 250 WG® (thiamethoxam 250 g kg-1) in differentiated human neuroblastoma SH-SY5Y cell line.

Methods

Cells were incubated with the pesticides for 96 h, and the cytotoxicity was evaluated through the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium·bromide (MTT) reduction and neutral red (NR) uptake assays. Toxicological pathways such as reactive oxygen (ROS) and nitrogen species (RNS) production, mitochondrial membrane potential, cell death mode, and the expression of the pro-apoptotic protein Bax were also evaluated.

Results

EC50 values of 266.4, 4,175, and 653.2 mg L-1 were found for Much®, Evidence® and Actara®, respectively. Significant increases in ROS and RNS generation were observed for all pesticides, while mitochondrial membrane potential and Bax protein expression showed no significant changes. Analysis of cell death mode revealed an increase in early apoptotic cells.

Conclusion

Therefore, neonicotinoid insecticides are potentially neurotoxic, reinforcing concerns about human exposure to these commercial formulations.

Effects of the insecticide imidacloprid on aquatic invertebrate communities of the Ecuadorian Amazon

Imidacloprid is a neonicotinoid insecticide that has received particular attention due to its widespread use and potential adverse effects for aquatic and terrestrial ecosystems. Its toxicity to aquatic organisms has been evaluated in central and southern Europe as well as in (sub-)tropical regions of Africa and Asia, showing high toxic potential for some aquatic insects and zooplankton taxa. However, its toxicity to aquatic organisms representative of tropical regions of Latin America has never been evaluated. To fill this knowledge gap, we carried out a mesocosm experiment to assess the short- and long-term effects of imidacloprid on freshwater invertebrate communities representative of the Ecuadorian Amazon. A mesocosm experiment was conducted with five weekly applications of imidacloprid at four nominal concentrations (0.01 μg/L, 0.1 μg/L, 1 μg/L and 10 μg/L). Toxic effects were evaluated on zooplankton and macroinvertebrate populations and communities, as well as on water quality parameters for 70 days. Given the climatic conditions prevailing in the study area, characterized by a high solar radiation and abundant rainfall that resulted in mesocosm overflow, there was a rapid dissipation of the test compound from the water column (half-life: 4 days). The macroinvertebrate taxa Callibaetis pictus (Ephemeroptera), Chironomus sp. (Diptera), and the zooplankton taxon Macrocyclops sp., showed population declines caused by the imidacloprid treatment, with a 21-d Time Weighted Average No Observed Effect Concentrations (21-d TWA NOEC) of 0.46 μg/L, except for C. pictus which presented a 21-d TWA NOEC of 0.05 μg/L. In general terms, the sensitivity of these taxa to imidacloprid was greater than that reported for surrogate taxa in temperate zones and similar to that reported in other (sub-)tropical regions. These results confirm the high sensitivity of tropical aquatic invertebrates to this compound and suggest the need to establish regulations for the control of imidacloprid contamination in Amazonian freshwater ecosystems.

Design, Synthesis, and Antifeedant Activity Evaluation of 13/14-Arylthioether Matrine Derivatives

Introducing a sulfur atom into active agricultural molecules is an important strategy for pesticide development. Matrine, an environmentally friendly botanical pesticide, has the advantage of being easily degraded and has drawn attention in the agricultural field. To explore the novel matrine-type pesticides, in this study, we designed and synthesized 13/14-arylthioether matrine derivatives by introducing various aryl sulfide motifs into bioactive matrine. Most of the synthesized arylthioether matrines exhibited good antifeedant activity against Spodoptera exigua. Among them, compound 2q showed the best antifeedant effect with an EC50 value of 0.038 mg/mL, which is approximately 125-fold more activity than matrine and reached the activity level of commercial standard azadirachtin A. Furthermore, compound 2q exhibited an inhibitory effect on antifeedant-related enzyme carboxylesterase (CarE) from S. exigua. In short, the high activity of arylthioether matrines offers new insights into developing new antifeedants.

Short- and long-term effects of commercial formulations of imidacloprid, spirotetramat, and mixtures of these active ingredients on pupae of Diaeretiella rapae (Hymenoptera: Braconidae) and its progeny

BACKGROUND

Compatibility studies of insecticides and natural enemies usually focus on short-term lethal effects, without considering the long-term sublethal effects (including progeny). Even less-explored are the effects of commercial insecticides formulated with more than one active product. Short- and long-term lethal and sublethal effects were studied for the first time on the progeny of commercial formulations of spirotetramat, imidacloprid and a commercial mixture of these active ingredients on pupae of Diaeretiella rapae (M'ntosh) (Hymenoptera: Braconidae), an endoparasitoid of aphids considered to be a potential biological control agent. Insecticides were exposed topically on aphid mummies in which the parasitoid was in the pupal stage.

RESULTS

Imidacloprid reduced adult emergence by more than 30% and prolonged intra-host development time with respect to control from half the maximum recommended field dose (MFRD). Spirotetramat and commercial mixture only showed significant effects on these endpoints at doses above the MFRD. The tested formulations did not affect adult longevity, sex ratio, and percentage of parasitism in the exposed generation. At low concentrations the active ingredients in the commercial mixture behave synergistically, whereas at medium and high concentrations they behave antagonistically. Considering the 10% lethal dose (LD10), imidacloprid showed the highest hazard coefficient, whereas the commercial mixture was more hazardous when considering the LD50 and LD90. The commercial mixture and imidacloprid induced higher adult emergence and altered the sex ratio in the progeny.

CONCLUSIONS

The following order of toxicity on D. rapae can be established: imidacloprid > commercial mixture > spirotetramat. Joint use of this species with imidacloprid and commercial mixture should be avoided in integrated pest management programs. © 2024 Society of Chemical Industry.

Thiamethoxam toxicity on the stingless bee Friesiomelitta varia: LC50, survival time, and enzymatic biomarkers assessment

Bees play a crucial role as pollinating insects in both natural and cultivated areas. However, the use of pesticides, such as thiamethoxam, has been identified as a contributing factor compromising bee health. The current risk assessment primarily relies on the model species Apis mellifera, raising concerns about the applicability of these assessments to other bee groups, including stingless bees. In this study, we investigated the acute toxicity of thiamethoxam on the stingless bee Frieseomelitta varia by determining the average lethal concentration (LC50) and mean lethal time (LT50). Additionally, we evaluated the enzymatic profile of Acetylcholinesterase (AChE), Carboxylesterase-3 (CaE-3), and Glutathione S-Transferase (GST), in the heads and abdomens of F. varia after exposure to thiamethoxam (LC50/10). The LC50 of thiamethoxam was determined to be 0.68 ng ai/μL, and the LT50 values were 37 days for the control group, 25 days at LC50/10, and 27 days at LC50/100. The thiamethoxam significantly decreased the survival time of F. varia. Furthermore, the enzymatic profile exhibited differences in CaE3 activity within one day in the heads and ten days in the abdomen. GST activity showed differences in the abdomen after one and five days of thiamethoxam exposure. These findings suggests that the abdomen is more affected than the head after oral exposure to thiamethoxam. Our study provides evidence of the toxicity of thiamethoxam at both the cellular and organismal levels, reinforcing the need to include non-Apis species in pollinator risk assessments. and provide solid arguments for bee protection.

Nitenpyram in tea: Eco-friendly detection methodology and residue behavior

Studies on nitenpyram determination and behavior within tea remain limited despite its widespread use as a neonicotinoid. An organic-saving analytical approach tailored for the detection of nitenpyram in tea was established. Nitenpyram was extracted by boiling water and cleaned up by Cleanert PCX solid-phase. The average recoveries were 75.1-94.5 %, with relative standard deviations (RSDs) of 0.7-8.6 % for saving 34.5-88.6 % organic solvent. The limits of quantification (LOQs) were 0.002 mg·kg-1 in fresh tea shoots, 0.005 mg·kg-1 in made tea, and 0.001 mg·L-1 in tea brew, satisfying the current minimum Maximum Residue Limit (MRL). Nitenpyram dissipated rapidly with half-lives of 1.2-1.4 days at the recommended dosage (27 g a.i. ha-1) in two locations. Remarkably, 20-110 % of nitenpyram was leached out from made tea in different brewing modes. This work provides insights into nitenpyram's rational application in tea cultivation and offers considerations to institutions tasked with unestablished MRLs in tea.

Regenerated SERS substrate based on Ag/AuNPs-TiO2-oxidized carbon cloth for detection of imidacloprid

Imidacloprid (IMI) are widely used in modern tea industry for pest control, but IMI residues pose a great threat to human health. Herein, we propose a regeneration metal-semiconductor SERS substrate for IMI detection. We fabricated the SERS sensor through the in-situ growth of a nano-heterostructure incorporating a semiconductor (TiO2) and plasmonic metals (Au, Ag) on oxidized carbon cloth (OCC). Leveraging the high-density hot spots, the formed Ag/AuNPs-TiO2-OCC substrate exhibits higher enhancement factors (1.92 × 108) and uniformity (RSD = 7.68%). As for the detection of IMI on the substrate, the limit of detection was lowered to 4.1 × 10-6 μg/mL. With a hydrophobic structure, the Ag/AuNPs-TiO2-OCC possessed excellent self-cleaning performance addressing the limitation of single-use associated with traditional SERS substrates, as well as the degradation capability of the substrate under ultraviolet (UV) light. Accordingly, Ag/AuNPs-TiO2-OCC showcases outstanding SERS sensing and regenerating properties, making it poised for extensive application in the field of food safety assurance.

Environmentally relevant concentrations of nickel and imidacloprid induce reproductive toxicity in earthworm (Eisenia fetida fetida)

The current research investigates individual and combined toxicity effects of nickel (Ni) and imidacloprid (IMI) on earthworm species Eisenia fetida fetida. Employing standardized toxicity parameters, we assessed the impact of environmentally relevant concentrations (ERC) of Ni, IMI, and their mixtures on key biomarkers and reproductive fitness of earthworms. Our findings reveal concentration-dependent responses with discernible adverse effects on physiological parameters. The ERC obtained for Ni was 0.095 ppm, and for imidacloprid was 0.01 ppm. Two concentrations (ERC and 1/5th) of both toxicants (individually and in combinations) were further given for 14 days, and parameters like avoidance behaviour, antioxidants, histology, and metabolomic profile were observed. The behaviour of earthworms was noted, where at 24-48 h, it was found to be in control soil, while later, at 72-96 h, they migrated to toxicants-treated soil. Levels of antioxidants (superoxide dismutase, catalase, reduced glutathione, ascorbic acid), lipid peroxidation, and lactate dehydrogenase were elevated in the testis, spermatheca, ovary, and prostate gland in a high concentration of Ni + IMI. Histological studies showed more vacuolization and disruption of epithelium that was increased in the prostate gland of the Ni + IMI high group, decreased number of spermatids, and damaged cell architecture was noted in testis and spermatheca of the Ni + IMI high group. The highest number of metabolites was found in Ni exposed group (181), followed by IMI (131) and Control (125). Thus, this study sheds light on the ecotoxicological effects of combinational exposure of these contaminants on an essential soil-dwelling organism, where IMI was more toxic than Ni, and both toxicants decreased earthworm reproductive fecundity.

Functional assessment of CYP3A4 and CYP2C19 genetic polymorphisms on the metabolism of clothianidin invitro

Clothianidin, classified as a second-generation neonicotinoid, has achieved extensive application due to its high efficacy against insect pests. This broad-spectrum usage has resulted in its frequent detection in environmental surveys. CYP2C19 and CYP3A4 are crucial for converting clothianidin to desmethyl-clothianidin (dm-clothianidin). The expression of these CYP450s can be significantly influenced by genetic polymorphisms. The objective of our research was to examine the catalytic effects of 27 CYP3A4 variants and 31 CYP2C19 variants on the metabolism of clothianidin within recombinant insect microsomes. These variants were assessed through a well-established incubation procedure. In addition, the concentration of its metabolite dm-clothianidin was quantified by employing an ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Lastly, the kinetic parameters of these CYP3A4 and CYP2C19 variants were calculated by applying Michaelis-Menten kinetic analysis to fit the data. The observed changes in enzyme activity were related to the metabolic transformation of clothianidin to dm-clothianidin. In the CYP2C19 metabolic pathway, one variant (CYP2C19.23) showed no notable change in intrinsic clearance (CLint), four variants (CYP2C19.29, .30, .31 and L16F) demonstrated a marked increase in CLint (110.86-183.46 %), and the remaining 25 variants exhibited a considerable decrease in CLint (26.38-89.79 %), with a maximum decrease of 73.62 % (CYP2C19.6). In the CYP3A4 metabolic pathway, 26 variants demonstrated significantly reduced CLint (10.54-52.52 %), with a maximum decrease of 89.46 % (CYP3A4.20). Our results suggested that most variants of CYP3A4 and CYP2C19 significantly altered the enzymatic activities associated with clothianidin metabolism to various degrees. This study provides new insights into assessing the metabolic behavior of pesticides and delivers crucial data that can guide clinical detoxification strategies.

Neonicotinoids differentially modulate nicotinic acetylcholine receptors in immature and antral follicles in the mouse ovary†

Neonicotinoids are the most widely used insecticides in the world. They are synthetic nicotine derivatives that act as nicotinic acetylcholine receptor agonists. Although parent neonicotinoids have low affinity for the mammalian nicotinic acetylcholine receptor, they can be activated in the environment and the body to positively charged metabolites with high affinity for the mammalian nicotinic acetylcholine receptor. Imidacloprid, the most popular neonicotinoid, and its bioactive metabolite desnitro-imidacloprid differentially interfere with ovarian antral follicle physiology in vitro, but their effects on ovarian nicotinic acetylcholine receptor subunit expression are unknown. Furthermore, ovarian nicotinic acetylcholine receptor subtypes have yet to be characterized in the ovary. Thus, this work tested the hypothesis that ovarian follicles express nicotinic acetylcholine receptors and their expression is differentially modulated by imidacloprid and desnitro-imidacloprid in vitro. We used polymerase chain reaction, RNA in situ hybridization, and immunohistochemistry to identify and localize nicotinic acetylcholine receptor subunits (α2, 4, 5, 6, 7 and β1, 2, 4) expressed in neonatal ovaries (NO) and antral follicles. Chrnb1 was expressed equally in NO and antral follicles. Chrna2 and Chrnb2 expression was higher in antral follicles compared to NO and Chrna4, Chrna5, Chrna6, Chrna7, and Chrnb4 expression was higher in NO compared to antral follicles. The α subunits were detected throughout the ovary, especially in oocytes and granulosa cells. Imidacloprid and desnitro-imidacloprid dysregulated the expression of multiple nicotinic acetylcholine receptor subunits in NO, but only dysregulated one subunit in antral follicles. These data indicate that mammalian ovaries contain nicotinic acetylcholine receptors, and their susceptibility to imidacloprid and desnitro-imidacloprid exposure varies with the stage of follicle maturity.

Pyridine Derivatives as Insecticides. Part 5. New Thieno[2,3-b]pyridines and Pyrazolo[3,4-b]pyridines Containing Mainly Ethyl Nicotinate Scaffold and Their Insecticidal Activity toward Aphis gossypii (Glover,1887)

Ethyl 5-cyano-1,6-dihydro-2-methyl-4-(2'-thienyl)-6-thioxonicotinate (A) was synthesized and reacted with ethyl chloroacetate in the presence of sodium acetate or sodium carbonate to give ethyl 5-cyano-6-((2-ethoxy-2-oxoethyl)thio)-2-methyl-4-(2'-thienyl)nicotinate (1a) or its isomeric thieno[2,3-b]pyridine 2a. 3-Aminothieno[2,3-b]pyridine-2-carboxamide 2b was also synthesized by the reaction of A with 2-chloroacetamide. The reaction of 1a with hydrazine hydrate in boiling ethanol gave acethydrazide 3. Heating ester 1a with hydrazine hydrate under neat conditions afforded 3-amino-1H-pyrazolo[3,4-b]pyridine 10. Compounds 2b, 3, and 10 were used as precursors for synthesizing other new thieno[2,3-b]pyridines and pyrazolo[3,4-b]pyridines containing mainly the ethyl nicotinate scaffold. Structures of all new compounds were confirmed by elemental and spectral analyses. Most of the obtained compounds were evaluated for their insecticidal activity toward the nymphs and adults of Aphis gossypii (Glover,1887). Some compounds such as 4, 9b, and 9c showed promising results. The effect of some sublethal concentrations, less than LC50, of compounds 4, 9b, and 9c on the examined Aphis was subjected to a further study. The results demonstrated that exposure of A. gossypii nymphs to sublethal concentrations of compounds 4, 9b, and 9c had noticeable effects on their biological parameters, i.e., nymphal instar duration, generation time, and adult longevity. The highest concentration C1 of all three compounds increased the nymphal instar duration and generation time and decreased adult longevity and vice versa.

Developmental toxicity of the neonicotinoid pesticide clothianidin to the larvae of the crustacean Decapoda, Penaeus vannamei

The developmental toxicity effects of neonicotinoid pesticides such as clothianidin have not been fully explored in agricultural applications. This is particularly noteworthy because such pesticides significantly impact the survival rates of invertebrates, with arthropod larvae being particularly vulnerable. This study aimed to address this research gap by specifically investigating the toxicological effects of clothianidin on the developmental stages of the larvae of the economically important aquaculture species Penaeus vannamei. In these experiments, shrimp eggs were exposed to seawater containing different concentrations of clothianidin beginning at N1, and each phase was observed and analyzed to determine its toxic impact on larval development. These results revealed that clothianidin induces an increase in deformity rates and triggers abnormal cell apoptosis. It also significantly reduced survival rates and markedly decreased body length and heart rate in the later stages of larval development (P3). Transcriptomic analysis revealed disruptions in larval DNA integrity, protein synthesis, and signal transduction caused by clothianidin. To survive prolonged exposure, larvae may attempt to maintain their viability by repairing cell structures and enhancing signal transduction mechanisms. This study offers the first empirical evidence of the toxicity of clothianidin to arthropod larvae, underscoring the impact of environmental pollution on aquatic health.

Structural gonadal lesions observed in Japanese quail (Coturnix coturnix japonica) following exposure during puberty to the neonicotinoid pesticide, imidacloprid

Exposure to the neonicotinoid insecticide, imidacloprid (IMI), causes reproductive toxicity in mammals and reptiles. However, reports on the effects of IMI on the gonads in birds are grossly lacking. Therefore, this study investigated the effects of pubertal exposure to IMI on the histology, ultrastructure, as well as the cytoskeletal proteins, desmin, smooth muscle actin and vimentin, of the gonads of Japanese quail (Coturnix coturnix japonica). Quails were randomly divided into four groups at 5 weeks of age. The control group was given only distilled water, whereas, the other three experimental groups, IMI was administered by oral gavage at 1.55, 3.1, and 6.2 mg/kg, twice per week for 4 weeks. Exposure to IMI doses of 3.1 and 6.2 mg/kg caused dose-dependent histopathological changes in the ovary and testis. In the ovary, accumulation of lymphocytes, degenerative changes, and necrosis with granulocyte infiltrations were observed, while in the testis, distorted seminiferous tubules, germ cell sloughing, vacuolisations, apoptotic bodies, autophagosomes, and mitochondrial damage were detected. These changes were accompanied by a decreased number of primary follicles (P ≤ 0.05) in the ovary and a decrease (P ≤ 0.05) in the epithelial height, luminal, and tubular diameters of seminiferous tubules at the two higher dosages. In addition, IMI had a negative effect on the immunostaining intensity of desmin, smooth muscle actin, and vimentin in the ovarian and testicular tissue. In conclusion, exposure to IMI during puberty can lead to a range of histopathological alterations in the gonads of Japanese quails, which may ultimately result in infertility.

Molecular mechanisms for selective action of afidopyropen to Myzus persicae and Coccinella septempunctata

BACKGROUND

Afidopyropen is a novel insecticide with high selectivity between sucking insects such as the peach aphids Myzus persicae and natural enemies like the seven-spotted lady beetle Coccinella septempunctata. However, the mechanisms of selective action for afidopyropen remain unknown.

RESULTS

The LC50 values of afidopyropen to the 1st-4th instar larvae and adult C. septempunctata were 372- to more than 7267-fold higher than that to adult M. persicae. Though the activity of cytochrome P450s in M. persicae was 6.1- to 7.5-fold higher than that in C. septempunctata, the latter has much higher activities of carboxylesterase (CarEs) and glutathione S-transferases (GSTs), and the crude enzyme of C. septempunctata and M. persicae showed similar metabolism efficiency to afidopyropen. Molecular docking results demonstrated that afdopyropen showed higher binding affinity to the vanilloid-type transient receptor potential (TRPV) channel of M. persicae (-9.1 kcal/mol) than to that of C. septempunctata (-8.2 kcal/mol). And the EC50 value of afdopyropen to the TRPV channel of C. septempunctata (41 360 nM) was 19 885-fold higher than that in M. persicae (2.08 nM).

CONCLUSIONS

Our results demonstrated that the significantly different sensitivity of M. persicae and C. septempunctata TRPV channel to afidopyropen play a key role in the high selectivity of afidopyropen. These findings provide new insights into the selective mechanisms of afidopyropen against insect pests and natural enemies as well as the theory support for coordinated application of chemical control and biological control. © 2024 Society of Chemical Industry.

A Recyclable Luminescent MOF Sensor for On-Site Detection of Insecticide Dinotefuran and Anti-Parkinson's Drug Entacapone in Various Environmental and Biological Specimens

The monitoring and precise determination of pesticides and pharmaceutical drugs and their residues have become increasingly important in the field of food safety and water contamination issues. Herein, a fluorescent aluminium MOF-based sensor (1) was developed for the selective recognition of neonicotinoid insecticide dinotefuran and anti-Parkinson's drug entacapone. Guest-free MOF 1' exhibited ultra-fast response (<5 s) and ultra-low detection limits of 2.3 and 7.6 nM for dinotefuran and entacapone, which are lower than the previously reported MOF-based sensors. In the presence of other competitive analytes, great selectivity was achieved towards both analytes. The probe was recyclable up to five cycles. The sensing ability was explored towards entacapone in human serum, urine and dinotefuran in real soil, rice, honey samples, different fruits, vegetables, real water specimens and a wide range of pH media. A low-cost, handy MOF-based polymer thin-film composite (1'@PVDF-PVP) was developed for the on-site detection of dinotefuran and entacapone. Mechanistic studies involving analytical techniques and theoretical calculations suggested that FRET and PET are the probable reasons for entacapone sensing whereas IFE is responsible for dinotefuran detection. The entire work presents a low cost, multi-use photoluminescent sensor of entacapone and dinotefuran to address the environmental pollution.

Neonicotinoid Pesticides Affect Developing Neurons in Experimental Mouse Models and in Human Induced Pluripotent Stem Cell (iPSC)-Derived Neural Cultures and Organoids

Neonicotinoids are synthetic, nicotine-derived insecticides used worldwide to protect crops and domestic animals from pest insects. The reported evidence shows that they are also able to interact with mammalian nicotine receptors (nAChRs), triggering detrimental responses in cultured neurons. Exposure to high neonicotinoid levels during the fetal period induces neurotoxicity in animal models. Considering the persistent exposure to these insecticides and the key role of nAChRs in brain development, their potential neurotoxicity on mammal central nervous system (CNS) needs further investigations. We studied here the neurodevelopmental effects of different generations of neonicotinoids on CNS cells in mouse fetal brain and primary cultures and in neuronal cells and organoids obtained from human induced pluripotent stem cells (iPSC). Neonicotinoids significantly affect neuron viability, with imidacloprid (IMI) inducing relevant alterations in synaptic protein expression, neurofilament structures, and microglia activation in vitro, and in the brain of prenatally exposed mouse fetuses. IMI induces neurotoxic effects also on developing human iPSC-derived neurons and cortical organoids. Collectively, the current findings show that neonicotinoids might induce impairment during neuro/immune-development in mouse and human CNS cells and provide new insights in the characterization of risk for the exposure to this class of pesticides.

Early-Life Sublethal Exposure to Thiacloprid Alters Adult Honeybee Gut Microbiota

Thiacloprid, a neonicotinoid pesticide, is known to affect the gut microbiome of honeybees, yet studies often focus on immediate alternations during exposure, overlooking long-term microbiological impacts post-exposure. This study investigates the influences of sublethal thiacloprid administered during the larval developmental stage of honeybees on physiological changes and gut microbiota of adult honeybees. We found that thiacloprid exposure increased mortality and sugar intake in emerged honeybees. Using 16S rDNA sequencing, we analyzed intestinal microbial diversity of honeybees at one and six days post-emergence. Our findings reveal a significant but transient disruption in gut microbiota on day 1, with recovery from dysbiosis by day 6. This study emphasizes the importance of evaluating chronic sublethal exposure risks of thiacloprid to protect honeybee health.

Treatment of an accident of imidacloprid poisoning

Objective: Accidental oral imidacloprid poisoning occurred in a family in Shandong, China, in May 2023. This study aimed to analyze the clinical characteristics of this imidacloprid poisoning event and investigated the detection of toxicants. Methods: Clinical data of four patients with oral imidacloprid poisoning were collected and retrospectively analyzed. The relevant literature was then reviewed. Results: Four patients from the same family received different oral doses of imidacloprid. The main clinical manifestations were digestive and neurological symptoms, including nausea, vomiting, and varying degrees of consciousness. Laboratory tests showed an increased white blood cell count, neutrophil proportion, and mild elevation of transaminase and urea nitrogen levels in some patients. Following comprehensive treatment, which included hemoperfusion, gastric lavage, total gastrointestinal decontamination, and drug symptomatic treatment, the patient's symptoms were quickly relieved, and the concentration of imidacloprid in the blood rapidly decreased. Conclusion: Toxicant detection is an important criterion for the differential diagnosis of poisoning and is helpful for disease assessment, treatment plan formulation, and in determining patient prognosis.

Imidacloprid Uptake and Accumulation in Lettuce Plant (Lactuca sativa L. var. longipolia) and Its Effects on Abundance of Microbial Communities in Cultivated and Non-Cultivated Arid Soil

Systemic plant protection products, such as neonicotinoids (NIs), are capable of being translocated throughout a plant. Although NIs are less toxic to mammals, fish, and birds, their impact on microbial and non-target insects is of concern. This study investigates the uptake, translocation, and accumulation of the NI, imidacloprid (IMI), in romaine lettuce (Lactuca sativa L. var. longipolia). Exposing 15-day-old seedlings to "10 mg/L" of IMI, the effects on microbial communities in both cultivated (CS) and non-cultivated soil (NCS) were studied along with IMI translocation within plant tissues. The concentrations of IMI in soil varied temporally and between soil types after initial application, with a decrease from 2.0 and 7.7 mg/kg on the first day of sampling to 0.5 and 2.6 mg/kg on the final sampling day (day 35) for CS and NCS, respectively. The half-life of IMI soil was 10.7 and 72.5 days in CS and NCS, respectively, indicating that IMI degraded more quickly in CS, possibly due to smaller grain size, aeration, microbial degradation, and water flow. The accumulated concentrations of IMI in lettuce tissues ranged from 12.4 ± 0.2 and 18.7± 0.9 mg/kg in CS and NCS, respectively. The highest concentration of IMI was found in the shoots, followed by the roots, whereas the soil showed the lowest IMI residuals at the end of the trial. Soil bacteria and fungi were altered by the application of IMI, with a lower abundance index within the bacterial community, indicating a negative impact on the distribution of bacteria in the soil.

Evaluating the Safety of Imidacloprid FS Seed Treatment Use in Potato Production: A Case Study from China

This study evaluated the residue behavior and dissipation dynamics of a new imidacloprid FS 600 seed treatment in potato cultivation systems in Shandong and Jilin, China. Sensitive and accurate UPLC-MS/MS methods were established to quantify imidacloprid residues in potatoes, potato plants, and soil. Results showed that imidacloprid dissipation followed a first-order kinetic model, with half-lives ranging from 6.9 to 26.7 days in plants and 19.8 to 28.9 days in soil. At harvest, the highest average residues in potatoes and soil were 0.778 mg/kg and 0.149 mg/kg, respectively. The dietary risk assessment indicated a chronic risk quotient (CRQ) of 39.73% for adults, indicating minimal risk to human consumers, while the ecological risk quotient (ERQ) and ecotoxicity exposure ratio (TER) revealed low to moderate toxicity to earthworms, warranting caution in the use of this formulation. This research provides valuable data for assessing the safety of imidacloprid FS seed treatment in potato cultivation.

Decreases in the number of microglia and neural circuit dysfunction elicited by developmental exposure to neonicotinoid pesticides in mice

Neonicotinoids are insecticides widely used in the world. Although neonicotinoids are believed to be toxic only to insects, their developmental neurotoxicity in mammals is a concern. Therefore, we examined the effects of developmental exposure to neonicotinoids on immune system in the brain and post-developmental behaviors in this study. Imidacloprid or clothianidin was orally administered to dams at a dosage of 0.1 mg/kg/day from embryonic day 11 to postnatal day 21. Imidacloprid decreased sociability, and both imidacloprid and clothianidin decreased locomotor activity and induced anxiety, depression and abnormal repetitive behaviors after the developmental period. There was no change in the number of neurons in the hippocampus of mice exposed to imidacloprid. However, the number and activity of microglia during development were significantly decreased by imidacloprid exposure. Imidacloprid also induced neural circuit dysfunction in the CA1 and CA3 regions of the hippocampus during the early postnatal period. Exposure to imidacloprid suppressed the expression of csf1r during development. Collectively, these results suggest that developmental exposure to imidacloprid decreases the number and activity of microglia, which can cause neural circuit dysfunction and abnormal behaviors after the developmental period. Care must be taken to avoid exposure to neonicotinoids, especially during development.

Toxicity evaluation of neonicotinoids to earthworm (Eisenia fetida) behaviors by a novel locomotion tracking assay

Pesticides are substances used for controlling, preventing, and repelling pests in agriculture. Among them, neonicotinoids have become the fastest-growing class of insecticides because of their efficiency in targeting pests. They work by strongly binding to nicotinic acetylcholine receptors (nAChRs) in the central nervous system of insects, leading to receptor blockage, paralysis, and death. Despite their selectivity for insects, these substances may be hazardous to non-target creatures, including earthworms. Although earthworms may be invasive in some regions like north America, they contribute to the development of soil structure, water management, nutrient cycling, pollution remediation, and cultural services, positively impacting the environment, particularly in the soil ecosystem. Thus, this study aimed to develop a novel earthworm behavior assay since behavior is a sensitive marker for toxicity assay, and demonstrated its application in evaluating the toxicity of various neonicotinoids. Here, we exposed Eisenia fetida to 1 and 10 ppb of eight neonicotinoids (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram pestanal, thiacloprid, thiametoxam, and sulfoxaflor) for 3 days to observe their behavior toxicities. Overall, all of the neonicotinoids decreased their locomotion, showed by a reduction of average speed by 24.94-68.63% and increment in freezing time movement ratio by 1.51-4.25 times, and altered their movement orientation and complexity, indicated by the decrement in the fractal dimension value by 24-70%. Moreover, some of the neonicotinoids, which were acetamiprid, dinotefuran, imidacloprid, nitenpyram, and sulfoxaflor, could even alter their exploratory behaviors, which was shown by the increment in the time spent in the center area value by 6.94-12.99 times. Furthermore, based on the PCA and heatmap clustering results, thiametoxam was found as the neonicotinoid that possessed the least pronounced behavior toxicity effects among the tested pesticides since these neonicotinoid-treated groups in both concentrations were grouped in the same major cluster with the control group. Finally, molecular docking was also conducted to examine neonicotinoids' possible binding mechanism to Acetylcholine Binding Protein (AChBP), which is responsible for neurotransmission. The molecular docking result confirmed that each of the neonicotinoids has a relatively high binding energy with AChBP, with the lowest binding energy was possessed by thiametoxam, which consistent with its relatively low behavior toxicities. Thus, these molecular docking results might hint at the possible mechanism behind the observed behavior alterations. To sum up, the present study demonstrated that all of the neonicotinoids altered the earthworm behaviors which might be due to their ability to bind with some specific neurotransmitters and the current findings give insights into the toxicities of neonicotinoids to the environment, especially animals in a soil ecosystem.

Molecular Mechanism Underlying ROS-Mediated AKH Resistance to Imidacloprid in Whitefly

Synthetic insecticides used to control Bemisia tabaci include organophosphorus, pyrethroids, insect growth regulators, nicotinoids, and neonicotinoids. Among these, neonicotinoids have been used continuously, which has led to the emergence of high-level resistance to this class of chemical insecticides in the whitefly, making whitefly management difficult. The adipokinetic hormone gene (AKH) and reactive oxygen species (ROS) play roles in the development of insect resistance. Therefore, the roles of AKH and ROS in imidacloprid resistance in Bemisia tabaci Mediterranean (MED; formerly biotype Q) were evaluated in this study. The expression level of AKH in resistant B. tabaci MED was significantly lower than that in sensitive B. tabaci (MED) (p < 0.05). AKH expression showed a decreasing trend. After AKH silencing by RNAi, we found that ROS levels as well as the expression levels of the resistance gene CYP6CM1 and its upstream regulatory factors CREB, ERK, and P38 increased significantly (p < 0.05); additionally, whitefly resistance to imidacloprid increased and mortality decreased (p < 0.001). These results suggest that AKH regulates the expression of resistance genes via ROS in Bemisia tabaci.

A review of biomolecules conjugated lanthanide up-conversion nanoparticles-based fluorescence probes in food safety and quality monitoring applications

Upconversion nanoparticles (UCNPs) are known to possess unique characteristics, which allow them to overcome a number of issues that plague traditional fluorescence probes. UCNPs have been employed in a variety of applications, but it is arguably in the realm of optical sensors where they have shown the most promise. Biomolecule conjugated UCNPs-based fluorescence probes have been developed to detect and quantify a wide range of analytes, from metal ions to biomolecules, with great specificity and sensitivity. In this review, we have given much emphasis on the recent trends and progress in the preparation strategies of bioconjugated UCNPs and their potential application as fluorescence sensors in the trace level detection of food industry-based toxicants and adulterants. The paper discusses the preparation and functionalisation strategies of commonly used biomolecules over the surface of UCNPs. The use of different sensing strategies namely heterogenous and homogenous assays, underlying fluorescence mechanisms in the detection process of food adulterants are summarized in detail. This review might set a precedent for future multidisciplinary research including the development of novel biomolecules conjugated UCNPs for potential applications in food science and technology.

Associations between neonicotinoids and liver function measures in US adults: National Health and Nutrition Examination Survey 2015-2016

Background

Toxicological studies indicate that neonicotinoids may be associated with disruptions in liver function due to an increase in oxidative stress. There are scant epidemiological studies investigating the chronic hepatotoxic effects of neonicotinoids.

Objective

To examine the association between detectable concentrations of parent neonicotinoids and neonicotinoid metabolites with liver function markers among US adults, and whether sex modifies this association.

Methods

National Health and Nutrition Examination Survey 2015-2016 data were used to estimate associations between detectable neonicotinoids and serum alkaline phosphatase (ALP), alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transaminase (GGT), albumin, total bilirubin, total protein, and Hepatic Steatosis Index (HSI) using multiple linear regression.

Results

Detectable levels of N-desmethyl-acetamiprid were associated with a decrease in GGT (β = -3.54 unit/l; 95% confidence interval [CI] = -6.48, -0.61) and detectable levels of 5-hydroxy-imidacloprid were associated with a decrease in HSI (β = -1.11; 95% CI = -2.14, -0.07). Sex modified the association between any parent neonicotinoid and ALP (Pint = 0.064) and the association between clothianidin and ALP (Pint = 0.019), with a pattern of positive associations in males and inverse associations in females, though stratified associations did not reach statistical significance. Sex also modified the association between 5-hydroxy-imidacloprid and total protein (Pint = 0.062), with a significant positive association in females (β = 0.14 g/dl; 95% CI = 0.03, 0.25) and a null association in males.

Conclusion

Detectable concentrations of neonicotinoid metabolites were inversely associated with GGT and HSI in US adults. Evidence suggests neonicotinoids may influence liver function differently depending on sex. Future research is recommended to replicate the findings as the study was limited in its cross-sectional nature and inability to examine continuous neonicotinoid concentrations with liver function.

Low-cost materials as vehicles for pesticides in aquatic media: a review of the current status of different biosorbents employed, optimization by RSM approach

Water contamination by pesticides is increasing dramatically due to population growth and the extensive use of pesticides in agriculture, leading to grave environmental and health concerns. Thus, efficient processes and the design and development of effective treatment technologies are required due to the enormous demand for fresh water. The adsorption approach has been widely used to remove organic contaminants such as pesticides because of its performance, less expense, high selectivity, and simplicity of operation compared to other treatment technologies. Among alternative adsorbents, biomaterials abundantly available for pesticide sorption from water resources have attracted the attention of researchers worldwide. The main objective of this review article is to (i) present studies on a wide range of raw or chemically modified biomaterials potentially effective in removing pesticides from aqueous media; (ii) indicating the effectiveness of biosorbents as green and low-cost materials for removing pesticides from wastewater; and (iii) furthermore, report the application of response surface methodology (RSM) for modeling and optimizing adsorption.

One like all? Behavioral response range of native and invasive amphipods to neonicotinoid exposure

Native and invasive species often occupy similar ecological niches and environments where they face comparable risks from chemical exposure. Sometimes, invasive species are phylogenetically related to native species, e.g. they may come from the same family and have potentially similar sensitivities to environmental stressors due to phylogenetic conservatism and ecological similarity. However, empirical studies that aim to understand the nuanced impacts of chemicals on the full range of closely related species are rare, yet they would help to comprehend patterns of current biodiversity loss and species turnover. Behavioral sublethal endpoints are of increasing ecotoxicological interest. Therefore, we investigated behavioral responses (i.e., change in movement behavior) of the four dominant amphipod species in the Rhine-Main area (central Germany) when exposed to the neonicotinoid thiacloprid. Moreover, beyond species-specific behavioral responses, ecological interactions (e.g. parasitation with Acanthocephala) play a crucial role in shaping behavior, and we have considered these infections in our analysis. Our findings revealed distinct baseline behaviors and species-specific responses to thiacloprid exposure. Notably, Gammarus fossarum exhibited biphasic behavioral changes with hyperactivity at low concentrations that decreased at higher concentrations. Whereas Gammarus pulex, Gammarus roeselii and the invasive species Dikerogammarus villosus, showed no or weaker behavioral responses. This may partly explain why G. fossarum disappears in chemically polluted regions while the other species persist there to a certain degree. But it also shows that potential pre-exposure in the habitat may influence behavioral responses of the other amphipod species, because habituation occurs, and potential hyperactivity would be harmful to individuals in the habitat. The observed responses were further influenced by acanthocephalan parasites, which altered baseline behavior in G. roeselii and enhanced the behavioral response to thiacloprid exposure. Our results underscore the intricate and diverse nature of responses among closely related amphipod species, highlighting their unique vulnerabilities in anthropogenically impacted freshwater ecosystems.