Pyrethroid-resistant Hyalella azteca with voltage-gated sodium channel mutations have been identified at multiple locations throughout California. In December 2013, H. azteca were collected from Mosher Slough in Stockton, CA, USA, a site with reported pyrethroid (primarily bifenthrin and cyfluthrin) sediment concentrations approximately twice the 10-d LC50 for laboratory-cultured H. azteca. These H. azteca were shipped to Southern Illinois University Carbondale and have been maintained in pyrethroid-free culture since collection. Even after 22 months in culture, resistant animals had approximately 53 times higher tolerance to permethrin than non-resistant laboratory-cultured H. azteca. Resistant animals held in culture also lacked the wild-type allele at the L925 locus, and had non-synonymous substitutions that resulted in either a leucine-isoleucine or leucine-valine substitution. Additionally, animals collected from the same site nearly three years later were again resistant to the pyrethroid permethrin. When resistant animals were compared to non-resistant animals, they showed lower reproductive capacity, lower upper thermal tolerance, and the data suggested greater sensitivity to, 4, 4′-dichlorodiphenyltrichloroethane (DDT), copper (II) sulfate, and sodium chloride. Further testing of the greater heat and sodium chloride sensitivity of the resistant animals showed these effects to be unrelated to clade association. Fitness costs associated with resistance to pyrethroids are well documented in pest species (including mosquitoes, peach-potato aphids, and codling moths) and we believe that H. azteca collected from Mosher Slough also have fitness costs associated with the developed resistance.

Soils and agricultural products from the Red River basin in Northern Vietnam were reported to be contaminated by agrichemicals. To assess potential exposure of local farmers and consumers to these contaminants, pesticide use and management practices of local farmers were surveyed and residue concentrations were determined for recently used as well as for banned pesticides in water, soil, vegetables, and fish samples in two communes of Northern Vietnam. DDTs, HCHs, and Drin compounds still persist at relatively high concentrations in soil and occur in vegetable and fish samples. Recently used pesticides, such as fenobucarb, trichlorfon, cyfluthrin, and cypermethrin were detected in vegetable and fish samples. Thresholds for acceptable daily intake levels (ADI) were frequently reached in the analyzed food products pointing to the fact that current pesticide management practices do not only result in a pollution of the environment but also pose threats to human health.

Constructed wetlands are a suggested best management practice to help mitigate agricultural runoff before entering receiving aquatic ecosystems. A constructed wetland system (180 m x 30 m), comprising a sediment retention basin and two treatment cells, was used to determine the fate and transport of simulated runoff containing the pyrethroid insecticides lambda-cyhalothrin and cyfluthrin, as well as suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results showed 49 and 76% of the study's measured lambda-cyhalothrin and cyfluthrin masses were associated with vegetation, respectively. Based on conservative effects concentrations for invertebrates and regression analyses of maximum observed wetland aqueous concentrations, a wetland length of 215 m x 30 m width would be required to adequately mitigate 1% pesticide runoff from a 14 ha contributing area. Results of this experiment can be used to model future design specifications for constructed wetland mitigation of pyrethroid insecticides. A wetland length of 215 m x 30 m mitigated pyrethroid runoff from a 14 ha field.

Water treatment and reuse initiatives are essential to combat declining water supplies in a changing climate, especially in arid and semi-arid regions. Pollution of water resources intensifies the search for strategies to provide water for potable and non-potable reuse that mitigates detrimental ecological and human health effects. Fipronil and synthetic pyrethroids are common urban-use insecticides that exert aquatic toxicity at trace levels and have been often found in urban surface streams. In this study, samples were collected from the 182 ha Prado Wetlands in Southern California for seven months to assess the occurrence of fipronil and its degradation products as well as pyrethroids (bifenthrin and cyfluthrin) in water, sediment, and plants in a 4.45 ha vegetated surface flow constructed wetland (CW). Concentration-based removal values and changes in mass flux were calculated to determine the efficacy of CW treatment. Observed water concentrations were further used to calculate toxic units for the invertebrates Hyalella azteca and Chironomus dilutus. Pesticide concentrations in water, sediment, and plant samples consistently decreased during passage through the CW at all time points. Removal values for fipronil desulfinyl, fipronil sulfide, fipronil, fipronil sulfone, bifenthrin, and cyfluthrin were 100%, 99.7–100%, 57.8–88.1%, 75.6–100%, 74.7–100%, and 36.6–82.2%, respectively, and there was a general net deposition of pesticides into CW compartments. Toxic unit values decreased in every instance for both aquatic invertebrates. Settling of contaminated particles, adsorption to sediment, plant uptake or adsorption, and subsequent degradation contributed to the effective removal of these urban-use insecticides, which highlights the potential of CWs for protecting urban water quality.

Risk assessments of the ecotoxicological effects insecticides impose on ectotherms have increasingly considered temperature. However, the changes toxicants induce in thermoregulatory behavioral traits may lead to a divergence of thermal selection and temperature-dependent changes of contaminant toxicity. This study demonstrated the interaction of behavioral thermoregulation and temperature-dependent toxicity of beta-cyfluthrin (BC) in the lizard Eremias argus. Based on the negative relationship between temperature and BC toxicity, seeking a warming environment was assumed to represent a self-rescue behavior (and vice versa). The results showed that BC-treated lizards (0–20 μg/g body weight (bw)) showed such self-rescue behavior, while lizards exposed to an extremely high BC dose (200 μg/g bw) sought a cooler environment. Biochemical assays showed that BC affected neurotransmitter systems, caused oxidative stress, and interfered with ion-transport in the central nervous system. Biomarkers of the cholinergic and glutamatergic system, ion-transport function, and oxidative stress were identified as potential biochemical variables related to thermoregulatory behavior. Apparently, seeking a warmer environment is a survival strategy with the aim to neutralize BC toxicity, while seeking a cooler environment aims to attenuate the harmful effects of metabolic and oxidative stress, and to decelerate internal BC diffusion. This phenomenon could be also explained by the concept of the “cooling trap”, i.e., a behavior where cooler temperatures are sought. This impairs survival after exposure to BC at it has a negative temperature coefficient, derived from a dysfunction of the central nervous system regarding thermoregulation caused by the high dosage of neurotoxicant and resulting temperature maladaptation. Implications of the interaction between thermoregulatory behavior and temperature-dependent toxicity are presented, which may aid further temperature-dependent risk assessments.

Pyrethroid pesticides occur in urban creek sediments at concentrations acutely toxic to sensitive aquatic life. To better understand the source of these residues, runoff from residential neighborhoods around Sacramento, California was monitored over the course of a year. Pyrethroids were present in every sample. Bifenthrin, found at up to 73 ng/L in the water and 1211 ng/g on suspended sediment, was the pyrethroid of greatest toxicological concern, with cypermethrin and cyfluthrin of secondary concern. The bifenthrin could have originated either from use by consumers or professional pest controllers, though the seasonal pattern of discharge from the drain was more consistent with professional use as the dominant source. Stormwater runoff was more important than dry season irrigation runoff in transporting pyrethroids to urban creeks. A single intense storm was capable of discharging as much bifenthrin to an urban creek in 3 h as that discharged over 6 months of irrigation runoff. Pyrethroid insecticides regularly detected in residential runoff at toxicologically significant concentrations.

Temporal–spatial distribution of synthetic pyrethroids (SPs) in overlying water and surface sediments and ecological risk to aquatic systems were investigated, where paired water and surface sediments were collected during dry and wet periods in Guangzhou urban waterways. Eight target SPs (i.e., tefluthrin, bifenthrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, esfenvalerate, and deltamethrin), with cypermethrin and permethrin as major components, were ubiquitously detected in both water (dissolved and particle phases, separately) and sediments. Significant increases of ΣSP (sum of eight SPs) concentrations were observed in both water and sediment from the dry period to the wet period. The spatial distribution of SPs was mostly impacted by land-use type, with the highest ΣSP concentrations in the residential areas, which indicates the massive application of pyrethroids in household mosquito control. It is demonstrated that SPs preferred to be adsorbed to the particles, and rainfall-induced runoff was suggested as an important mechanism that moved SPs to the receiving waterways. A rising trend on sediment concentrations of SPs in the Guangzhou area in the last decade implied increasing application of pyrethroid insecticides, with cypermethrin and permethrin as the dominant components, where the contamination of SPs was positively related with urbanization rate (e.g., resident population and green coverage area). A special emphasis was placed on the potential effects of both individual SPs and their mixtures in three trophic levels (i.e., algae, daphnia, and fish) using toxic units (TUs) and risk quotients (RQs) for water and sediments. In spite of no acute effects due to SPs in the sediments, the toxic units showed daphnia as the most sensitive species in water, with acute risks to daphnia exhibited in several sampling sites. The risk assessment points out that a chronic toxicity (RQ index) caused by SPs in three trophic levels (algae, daphnia, and fish) exists, especially in Daphnia magna. Graphical abstract

Feeding a growing population requires striking a balance between increasing production and decreasing environmental impacts in agricultural settings. We established 12 experimental mesocosms with silt loam atop a base of sand and examined the ability of three emergent aquatic plants common to the USA to remediate pesticides and nutrients in agricultural runoff. Mesocosms were planted in monocultures of Myriophyllum aquaticum, Polygonum amphibium, and Typha latifolia, or left unvegetated to serve as controls. All mesocosms were amended with target concentrations of 10 mg L⁻¹ (each) nitrate, ammonium, and orthophosphate; 20 μg L⁻¹ (each) of the pesticides propanil and clomazone; and 10 μg L⁻¹ of the pesticide cyfluthrin. After a 6-h-simulated agricultural runoff with amended water, mesocosms sat idle for 48 h before flushing with unamended water for another 6 h. Outflow water samples were collected and analyzed for contaminant concentrations. Most significant differences between vegetated mesocosms and controls occurred when comparing mean contaminant transfer/transformation rates post-amendment. Differences among plant species occurred regarding retention of dissolved nutrients orthophosphate, ammonium, and nitrate. Similarly, all three plant species retained more propanil than controls during post-amendment (8–48 h), but individual plant differences occurred with regard to clomazone and cyfluthrin retention. While variation in mitigation of specific dissolved components of nutrients suggests different mechanisms involved in nutrient cycling within our mesocosms, consistent overall total nutrient and pesticide reduction during the post-amendment period indicate that holding runoff in vegetated ditches may reduce transport of agricultural contaminants to downstream aquatic ecosystems.

This study was designed to assess the gradual increase in the use of insecticides on vegetables and to familiarize the consumers regarding the insecticide residues. The purpose of this research work was to highlight the detrimental effects of pyrethroids (bifenthrin, cyfluthrin, cypermethrin, deltamethrin, fenvalerate, lambda-cyhalothrin, and permethrin) compare with dietary intake assessment of eggplant and okra grown in peri-urban environment. In this manner, a total of 180 (n = 60 × 3) samples of eggplant (Solanum melongena) and okra (Abelmoschus esculentus) were procured from the peri-urban farming system of Faisalabad, Multan, and Gujranwala to assess the pyrethroid residues along with their dietary intake assessment. The procured vegetables were quantified for pyrethroid residues by using gas chromatography (GC) equipped with an electron capture detector (ECD). Outcomes of this study revealed that for okra samples, the highest residues of bifenthrin (1.25 mg kg⁻¹) were found in Gujranwala then Multan (1.5 mg kg⁻¹) and Faisalabad (1.04 mg kg⁻¹), whereas in eggplant, the highest residues were recorded for bifenthrin from Faisalabad (1.33 mg kg⁻¹) and Gujranwala (0.78 mg kg⁻¹). In Multan, the highest residues for cyfluthrin (1.18 mg kg⁻¹) were reported in eggplant. Out of all analyzed samples for pyrethroid residues, 32% samples contained detectable residues and 6% samples exceeded their maximum residual limits (MRLs) established by the European Union (EU). Dietary intake assessment (mg kg⁻¹ day⁻¹) was calculated as per their maximum permissible intake (MPI) values, i.e., bifenthrin (1.28), cyfluthrin (1.28), cypermethrin (3.20), deltamethrin (0.64), fenvalerate (1.28), lambda-cyhalothrin (0.064), and permethrin (3.20) respectively. Conclusively, residues from the Multan region were greater than those from Gujranwala and Faisalabad showing excessive application of pyrethroids. Overall results revealed that although some samples exceeded MRLs in selected areas, their safe consumption limit was found.

A multiresidue method was developed for the simultaneous determination of 31 emerging contaminants (pharmaceutical compounds, hormones, personal care products, biocides, and flame retardants) in aquatic plants. Analytes were extracted by ultrasound-assisted matrix solid-phase dispersion (UA-MSPD) and determined by gas chromatography-mass spectrometry after sylilation, The method was validated for different aquatic plants (Typha angustifolia, Arundo donax, and Lemna minor) and a semiaquatic cultivated plant (Oryza sativa) with good recoveries at concentrations of 100 and 25 ng g⁻¹ wet weight, ranging from 70 to 120 %, and low method detection limits (0.3 to 2.2 ng g⁻¹ wet weight). A significant difference of the chromatographic response was observed for some compounds in neat solvent versus matrix extracts, and therefore, quantification was carried out using matrix-matched standards in order to overcome this matrix effect. Aquatic plants taken from rivers located at three Spanish regions were analyzed, and the compounds detected were parabens, bisphenol A, benzophenone-3, cyfluthrin, and cypermethrin. The levels found ranged from 6 to 25 ng g⁻¹ wet weight except for cypermethrin that was detected at 235 ng g⁻¹ wet weight in O. sativa samples.