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Insecticides play a critical role in controlling the spread of insect-borne diseases and preserving crop health. These chemical substances are specifically formulated to kill or manage insect populations. Over the years, various types of insecticides have been developed, including organophosphates, carbamates, pyrethroids, and neonicotinoids, each with unique modes of action, physiological targets, and efficacy. Despite the advantages that insecticides offer, it is imperative to recognize the potential consequences on non-target species, the environment, and human health. It is therefore crucial to follow recommended label instructions and employ integrated pest management practices for the judicious use of insecticides. This review article provides an in-depth examination of the various types of insecticides, including their modes of action, physiological targets, environmental and human health impacts, and alternatives. The aim is to furnish a comprehensive overview of insecticides and to emphasize the significance of responsible and sustainable utilization.

Neonicotinoids are a novel class of insecticides that exhibit environmental persistence and off-target effects on both humans and ecosystems. Therefore, there is a need for sensitive and selective sensors to monitor concentrations of neonicotinoids in environmental water and soil systems. Molecularly imprinted polymer (MIP)-based sensors are an emerging technology with strong potential for reliable, sensitive, and selective detection of neonicotinoids. Moreover, MIPs are versatile and compatible with a wide range of analytical techniques, which can further enhance measurement capabilities in the development of practical and robust sensors. Despite this promise, many routes remain underexplored for neonicotinoid detection. This review reports on the current state of neonicotinoid chemical sensors and detection methods using MIPs and highlights potential applications of MIP-based approaches as cost-effective and easy-to-operate solutions for monitoring neonicotinoids. Recent sensors incorporating MIPs and electrochemical or optical techniques for neonicotinoid detection are described and compared. Approaches employing magnetic solid-phase extraction and quartz crystal microbalance are also discussed. Additionally, the influence of monomer choice for MIP synthesis, as well as the use of additives and nanomaterials for sensor construction and analyte detection, is reviewed. These methods may promote sustainability, reusability, ratiometric or simultaneous detection of neonicotinoids, and sensor portability for on-site monitoring.

Green coffee is essential in many tropical economies. Its cultivation often necessitates using pesticides that can leave behind residues harmful to human health. To ensure consumer safety, the European Community has set strict maximum residue limits (ranging from 0.01 to 1.0 mg/kg) for pesticides in green coffee sold within Europe. However, the lack of official testing methods for neonicotinoids (NEOs) is a problem, as laboratories must spend resources and time developing and validating suitable analytical methods. This study developed and validated a method for the simultaneous analysis of seven NEOs frequently used in coffee cultivation: acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid, and thiamethoxam. The proposed methodology uses Strata®-X PRO cartridges (solid-phase extraction) to remove interfering compounds present in the food matrix and high-performance liquid chromatography (HPLC), equipped with a diode array detector (DAD), to determine NEOs. The accuracy profile strategy validated the method’s suitability for the intended application. NEO recovery rates above 97%; negligible matrix effects (>93%); the linearity of the quantification method (R2 values above 0.99); relative biases and standard deviations below 5% and 6%, respectively; and an expected error rate less than 8% allowed to consider the method reliable for the intended objectives. Because of its low ecological impact and simple execution, this method can be used in routine analyses.

Neonicotinoid insecticides (neonicotinoids) are widely used in agriculture, forestry and public health in the world. Environmental exposure to neonicotinoids has been increasing due to their continuous uses. Neonicotinoids act as agonists, antagonists, or modulators of acetylcholine receptors and have adverse effects on non-target species, such as invertebrates, amphibians, reptiles, birds, microbes and mammals. Although there is concern about their adverse effects on ecosystem services and their potential effects on human health, their xenobiotic kinetics and dynamics in humans are not understood well. In this study, we determined a xenobiotic kinetic parameter, plasma protein bindings (PPBs) of 7 neonicotinoids and 18 metabolites with human plasma using a Rapid Equilibrium Dialysis (RED) device and liquid chromatography-tandem mass spectrometry (LC–MS/MS), and compared their PPBs with their physicochemical properties. 6-chloronicotinic acid (6-CNA) exhibited the highest PPB (86.4%), followed by imidacloprid-olefin (86.3%) in human plasma. Their PPBs are much higher than that of the parent compound, imidacloprid (27.5%). The PPBs of neonicotinoids and metabolites are not related to their lipophilicity determined by reversed-phase LC. The results shed light on the behavior of environmentally exposed neonicotinoids and metabolites and warrant further research on their xenobiotic kinetics and dynamics in humans.

Acetamiprid (ACE) is a kind of broad-spectrum pesticide that has potential health risk to human beings. Aptamers (Ap-DNA (1)) have a great potential as analytical tools for pesticide detection. In this work, a label-free electrochemical sensing assay for ACE determination is presented by electrochemical impedance spectroscopy (EIS). And the specific binding model between ACE and Ap-DNA (1) was further investigated for the first time. Circular dichroism (CD) spectroscopy and EIS demonstrated that the single strand AP-DNA (1) first formed a loosely secondary structure in Tris-HClO 4 (20 mM, pH = 7.4), and then transformed into a more stable hairpin-like structure when incubated in binding buffer (B-buffer). The formed stem-loop bulge provides the specific capturing sites for ACE, forming ACE/AP-DNA (1) complex, and induced the R CT (charge transfer resistance) increase between the solution-based redox probe [Fe(CN) 6 ] 3−/4− and the electrode surface. The change of Δ R CT (charge transfer resistance change, Δ R CT = R CT(after) - R CT(before) ) is positively related to the ACE level. As a result, the AP-DNA (1) biosensor showed a high sensitivity with the ACE concentration range spanning from 5 nM to 200 mM and a detection limit of 1 nM. The impedimetric AP-DNA (1) sensor also showed good selectivity to ACE over other selected pesticides and exhbited excellent performance in environmental water and orange juice samples analysis, with spiked recoveries in the range of 85.8% to 93.4% in lake water and 83.7% to 89.4% in orange juice. With good performance characteristics of practicality, sensitivity and selectivity, the AP-DNA (1) sensor holds a promising application for the on-site ACE detection.

The photodegradations of three selected neonicotinoid insecticides nitenpyram, thiacloprid, and acetamiprid were investigated in both water and soil samples under natural sunlight, UVA light, and UVB light. The results indicate that these insecticides undergo significant degradations when subjected to sunlight, whether they are in deionized (DI) water, tap water, and DI water containing 100 mg/L humic acids or in soil. The degradation half-lives of nitenpyram, thiacloprid, and acetamiprid in tap water under sunlight were found to be 3.7, 4.7, and 8.9 h, respectively, in DI water 5.4, 6.3, 9.1 h, respectively, in DI water containing 100 mg/L humic acids 3.6, 3.3, 6.5 h, respectively, and in soil 7.5, 7.9, and 15.9 h, respectively. The degradation due to hydrolysis was found insignificant as compared to photodegradation. The examination of the effects of light source revealed that the UVB in the sunlight plays a major role in the photodegradation of these three neonicotinoids, and the effects of UVA and visible light are negligible. The analysis on the degradation products indicated that the nitroguanidine group in these insecticides is unstable and prone to break up under sunlight. A total of nine degradation products were detected, of which the health effects and the fate and transport in the environment need to be further studied.

An acetamiprid-binding aptamer (ABA), gold nanoparticles (AuNPs) and upconversion nanoparticles (UCNPs) are used in a colorimetric and fluorometric method for the ultrasensitive and selective detection of the pesticide acetamiprid. The ABA is first configured into a duplex with a complementary DNA covalently attached to AuNPs. The resulting dsDNA-functionalized AuNP probe is not stable in 0.15 M NaCl solution and aggregates. This causing the color to change from red to purple. In the presence of acetamiprid, the ABA undergoes a structural switch from a DNA duplex to an aptamer-acetamiprid complex and consequently dissociates from the AuNPs. The partially unhybridized AuNPs are stable against salt-induced aggregation and show red color. The ratio of absorbances at 524 nm (red) and 650 nm (purple blue) varies with the concentration of acetamiprid in the 0.025–10 μM concentration range. The colorimetric signal can be further amplified by introducing DNA-modified carboxylated UCNPs (silica-coated NaYF 4 :Yb,Er) which display red and green fluorescence under 980 nm excitation. An inner filter effect occurs between DNA-modified UCNPs and dsDNA-modified AuNPs. The fluorometric assay is based on the measurement of the ratio of red (654 nm) and green (540 nm) fluorescence and works in the 0.025 to 1 μM acetamiprid concentration range and has a 0.36 nM detection limit (at a signal-to-noise ratio of 3). Because of the specificity of the aptamer, the assay is high selective. It was successfully used to quantify acetamiprid in contaminated real samples. Graphical abstract Schematic presentation of an upconversion fluorescent assay for acetamiprid. It involves the principle of analyte-triggered structural switch of aptamers, salt-induced AuNP aggregation, and signal amplification from UCNP.

A single-step preconcentration procedure using the in-situ formation of modified nickel–zinc-layered double hydroxides (LDHs) prior to high-performance liquid chromatography (HPLC) is investigated for the determination of neonicotinoid insecticide residues in honey samples. The LDHs could be prepared by the sequential addition of sodium hydroxide, sodium dodecyl sulfate, nickel nitrate 6-hydrate and zinc nitrate 6-hydrate, which were added to the sample solution. The co-precipitate phase and phase separation were obtained by centrifugation, and then the precipitate phase was dissolved in formic acid (concentrate) prior to HPLC analysis. Various analytical parameters affecting extraction efficiency were studied, and the characterization of the LDHs phase was performed using Fourier-transformed infrared spectroscopy and scanning electron microscopy. Under optimum conditions, the limit of detection of the studied neonicotinoids, in real samples, were 30 μg L−1, for all analytes, lower than the maximum residue limits established by the European Union (EU). The developed method provided high enrichment, by a factor of 35. The proposed method was utilized to determine the target insecticides in honey samples, and acceptable recoveries were obtained.

Anopheles darlingi is the main vector of malaria in Brazil, characterized by a high level of anthropophilia and endophagy. Imidacloprid, thiacloprid, and acetamiprid are the most widespread insecticides of the neonicotinoid group. However, they produce adverse effects on the non-target insects. Flupyradifurone has been marketed as an alternative to non-fluorinated neonicotinoids. Neonicotinoids containing trifluoroacethyl substituent reveal increased insecticidal activity due to higher hydrophobicity and metabolic stability. We synthesized novel neonicotinoid insecticides containing fluorinated acceptor groups and their interactions were estimated with the nicotinic acetylcholine receptor (nAChR) binding site by molecular docking studies, to evaluate their larvicidal activity against A. darlingi, and to assess their outdoor photodegradation behavior. New neonicotinoid analogues were prepared and characterized by NMR and mass-spectrometry. The synthesized molecules were modelled by time-dependent density functional theory and analyzed, their interaction with nAChR was investigated by molecular docking. Their insecticide activity was tested on Anopheles larvae collected in suburban area of Manaus, Brazil. Four new fluorinated neonicotinoid analogs were prepared and tested against 3rd instars larvae of A. darlingi showing high larvicidal activity. Docking studies reveal binding modes of the synthesized compounds and suggest that their insecticidal potency is governed by specific interactions with the receptor binding site and enhanced lipophilicity. 2-Chloro-5-(2-trifluoromethyl-pyrrolidin-1-ylmethyl)pyridine 5 showed fast degradation in water maintaining high larvicidal activity. All obtained substances possessed high larvicidal activity in low concentrations in 48 hours of exposure, compared to commercial flupyradifurone. Such activity is connected to a unique binding pattern of the synthesized compounds to insect's nAChR and to their enhanced bioavailability owing to introduction of fluorinated amino-moieties. Therefore, the compounds in question have a high potential for application as control agents for insects transmitting tropical diseases, and they will be less persistent in the environment.

The introduction of neonicotinoids for managing insecticide resistance in mosquitoes is of high interest as they interact with a biochemical target not previously used in public health. In this concern, Bayer developed a combination of the neonicotinoid clothianidin and the pyrethroid deltamethrin (brand name Fludora Fusion) as a new vector control tool. Although this combination proved to be efficient against pyrethroid-resistant mosquitoes, its ability to prevent the selection of pyrethroid and neonicotinoid resistance alleles was not investigated. In this context, the objective of this work was to study the dynamics and the molecular mechanisms of resistance of An. gambiae to the separated or combined components of this combination. A field-derived An. gambiae line carrying resistance alleles to multiple insecticides at low frequencies was used as a starting for 33 successive generations of controlled selection. Resistance levels to each insecticide and target site mutation frequencies were monitored throughout the selection process. Cross resistance to other public health insecticides were also investigated. RNA-seq was used to compare gene transcription variations and polymorphisms across all lines. This study confirmed the potential of this insecticide combination to impair the selection of resistance as compared to its two separated components. Deltamethrin selection led to the rapid enrichment of the kdr L1014F target-site mutation. Clothianidin selection led to the over-transcription of multiple cytochrome P450s including some showing high homology with those conferring neonicotinoid resistance in other insects. A strong selection signature associated with clothianidin selection was also observed on a P450 gene cluster previously associated with resistance. Within this cluster, the gene CYP6M1 showed the highest selection signature together with a transcription profile supporting a role in clothianidin resistance. Modelling the impact of point mutations selected by clothianidin on CYP6M1 protein structure showed that selection retained a protein variant with a modified active site potentially enhancing clothianidin metabolism. In the context of the recent deployment of neonicotinoids for mosquito control and their frequent usage in agriculture, the present study highlights the benefit of combining them with other insecticides for preventing the selection of resistance and sustaining vector control activities.