Risk Assessment Of Insecticides Research Articles

Side effects of semi-synthetic insecticide spinetoram on the whitefly parasitoid Encarsia formosa.

Insecticide risk assessment for biological control agents is essential for implementing integrated pest management (IPM) programs. Spinetoram is a naturally derived insecticide used to control a variety of agricultural sap-sucking insect pests, and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) plays a key role in the biocontrol of greenhouse whiteflies. Despite its presumed safe ecotoxicological profile, the side effects of spinetoram on E. formosa are partially unknown, especially at sublethal doses. In the laboratory, we estimated the lethal concentrations (LC) of spinetoram on E. formosa by topical exposure of pupae and 48 h residual contact exposure of emerged adults. Afterwards, we assessed the impact of spinetoram LCs on the life history traits (juvenile development, adult longevity, parasitism, adult emergence) and population growth parameter (the instantaneous rate of increase, ri) of the parasitoid. Probit analysis allowed the estimation of LC10 = 0.10 mg/L, LC50 = 0.56 mg/L, and LC90 = 3.28 mg/L. Spinetoram at LC10 had no impact on the observed parameters of E. formosa. Conversely, spinetoram at LC50 and LC90 significantly reduced adult longevity by 19.2% and 40.6%, total parasitism by 33.4% and 38.7%, and total adult emergence by 29.6% and 39.1%, respectively. Also, the ri of E. formosa was significantly affected by spinetoram LC50 and LC90 with a reduction of 8.17 and 29.83%, respectively. Our results suggested that spinetoram significantly threatens the effectiveness of E. formosa when applied at the field recommended rate. However, further validation of spinetoram under greenhouse conditions is required for a comprehensive risk assessment for E. formosa in IPM programs. © 2024 Society of Chemical Industry.

Method validation, residue behaviour and dietary risk assessment of insecticides (cyantraniliprole, acetamiprid, flubendiamide and its metabolite, des-iodo flubendiamide) in or on broccoli using LC-MS/MS.

Residue behaviour and dietary risk assessment of cyantraniliprole, flubendiamide and acetamiprid in broccoli were carried out using the QuEChERS (quick, easy, cheap, effective, rugged and safe) technique coupled with LC-MS/MS. The QuEChERS technique was validated on parameters such as linearity, accuracy, precision, robustness, matrix effects, limit of quantification (LOQ), specificity, retention time and ion ratio as per SANTE (Directorate General for Health and Food Safety) guidelines to attest to the specificity, accuracy and precision of the analytical method in estimating insecticide residues in and on broccoli heads and cropped soil. The LOQ of the method for all three insecticides was 0.01 mg/kg. The initial deposits of cyantraniliprole, flubendiamide and acetamiprid reduced to half of its concentration in 1.873-2.354, 1.975-2.484 and 1.371-1.620 days, respectively. No residues were detected in broccoli-cropped soil at harvest time (30 days after last spray). The proposed maximum residue limits (MRLs) of 1.5, 0.5-0.9 and 2.0-3mg/kg for cyantraniliprole, flubendiamide and acetamiprid were calculated using the Organisation for Economic Co-operation and Development MRL calculator. The acute and chronic dietary risk assessment of the tested insecticides identified no appreciable dietary risk to the Indian population from the consumption of broccoli heads. The findings of no dietary risk highlight the importance of informed pesticide usage in broccoli and the proposed MRL derived from this study offers crucial guidelines for the regulatory authorities, ensuring the safety of broccoli consumption.

Multiple stressor effects of insecticide exposure and increased fine sediment deposition on the gene expression profiles of two freshwater invertebrate species

BackgroundFreshwater ecosystem degradation and biodiversity decline are strongly associated with intensive agricultural practices. Simultaneously occurring agricultural stressors can interact in complex ways, preventing an accurate prediction of their combined effects on aquatic biota. Here, we address the limited mechanistic understanding of multiple stressor effects of two globally important stressors, an insecticide (chlorantraniliprole), and increased fine sediment load and assessed their impact on the transcriptomic profile of two stream macroinvertebrates: the amphipod Gammarus pulex and the caddisfly Lepidostoma basale.ResultsWe identified mainly antagonistic stressor interactions at the transcriptional level, presumably because the insecticide adsorbed to fine sediment particles. L. basale, which is phylogenetically more closely related to the insecticide’s target taxon Lepidoptera, exhibited strong transcriptional changes when the insecticide stressor was applied, whereas no clear response patterns were observed in the amphipod G. pulex. These differences in species vulnerability can presumably be attributed to molecular mechanisms determining the cellular affinity toward a stressor as well as differential exposure patterns resulting from varying ecological requirements between L. basale and G. pulex. Interestingly, the transcriptional response induced by insecticide exposure in L. basale was not associated with a disruption of the calcium homeostasis, which is the described mode of action for chlorantraniliprole. Instead, immune responses and alterations of the developmental program appear to play a more significant role.ConclusionsOur study shows how transcriptomic data can be used to identify multiple stressor effects and to explore the molecular mechanisms underlying stressor-induced physiological responses. As such, stressor effects assessed at the molecular level can inform about modes of action of chemicals and their interplay with non-chemical stressors. We demonstrated that stressor effects vary between different organismic groups and that insecticide effects are not necessarily covered by their described mode of action, which has important implications for environmental risk assessment of insecticides in non-target organisms.

Non‐neonicotinoid pesticides impact bumblebee activity and pollen provisioning

Abstract Bees are essential pollinators of crops and wild plants and their ability to forage and pollinate are key aspects of their behaviour. Bee populations are under threat, with the use of insecticides a contributing factor. Most research has focused on neonicotinoid insecticides and bee mortality, and little is known about impacts on bee foraging and delivery of pollination services. However, other insecticide classes, such as organophosphates and pyrethroids, are increasingly used globally, but little is known about how these widely used substances may impact bees, particularly non‐honeybees. We exposed bumblebee Bombus terrestris colonies to field‐relevant doses of a pyrethroid (lambda‐cyhalothrin) and an organophosphate (dimethoate) and investigated sublethal effects on behaviour at the individual and colony level, in addition to pollination service delivery under semi‐field conditions. We show, for the first time, that exposure to these chemicals impacts the activity and pollen provisioning of bumblebee Bombus terrestris audax colonies, while no short‐term effects on flower handling behaviour or pollination service delivery were detected. We found that colonies exposed to dimethoate were less active, with 67% fewer bees leaving the colony to forage than control colonies, and of those that returned, 92% fewer returned pollen provisions to the nest. Colonies exposed to lambda‐cyhalothrin did not differ in activity; however, 62% fewer of these bees returned with pollen provisions. Policy implications. These findings give important insights into how exposure to different classes of insecticides could impact bumblebee activity and their provision of pollen required for colony development. With a focus on neonicotinoids in terms of policy changes regarding insecticides and bees, we show that other insecticide classes should also be re‐examined in relation to their potential risks for pollinators. We confirm the need to improve risk assessment of insecticides to assess sublethal effects, include non‐honeybee species in risk assessment processes and also consider key behaviours such as foraging and interactions with plants.

Solitary bee behaviour and pollination service delivery is differentially impacted by neonicotinoid and pyrethroid insecticides

Solitary bees are important pollinators of crops and wild plants, and their decline poses a risk to the sustained provision of the services they provide. Although evidence suggests that exposure to insecticides can affect bees, most pesticide research and risk assessment has focussed on social bees and mortality while solitary species are understudied. The ability to forage is critical for solitary bee reproduction, also in how they deliver pollination services, and we know little about how insecticides can impact these behaviours. We exposed solitary red mason bees (Osmia bicornis) to field realistic levels of two widely used insecticides with differing modes of action (lambda-cyhalothrin (pyrethroid) and acetamiprid (neonicotinoid)), in a semi-field setting over multiple rounds of exposure. We then tested impacts on bee behaviour and pollination in apples, an important global insect-pollinated crop. Pollination by insecticide-treated bees reduced apple production by up to 86 % depending on the compound and the number of exposures, but the underlying mechanism behind this remains unclear and should be investigated further. Other measurements of pollination services including number of seeds per apple and stigma pollen deposition showed no relationship with pesticide treatment. Bee foraging behaviour was also affected by treatment where both insecticides appear to induce an excitatory effect which was constant for acetamiprid and eventually ceased for lambda-cyhalothrin after multiple exposures. This suggests that both neonicotinoid and non‑neonicotinoid insecticides can potentially affect behaviour and pollination services of solitary bees depending on how often they are exposed, which is particularly important given the changing usage patterns of these compound classes based on regulations around their use. This highlights the importance of moving insecticide risk assessment towards more field realistic scenarios and including sublethal effects on solitary and social bees, in addition to considering repeated exposures of bees to pesticides as is realistic in the field.

Response of wheat aphid to insecticides is influenced by the interaction between temperature amplitudes and insecticide characteristics.

Introduction: Climate change not only directly affects the phenotype of organisms but also indirectly impacts their physiology, for example, by altering their susceptibility to insecticides. Changed diurnal temperature fluctuations are an important aspect of climate change; ignoring the impact of these fluctuations on the biological effects of various chemical insecticides can lead to inaccurate assessments of insecticide risk under the current and future climate change scenarios. Methods: In this study, we studied effects of different temperature amplitudes (± 0, ± 6, ± 12°C) at the same mean temperature (22°C) on the life history traits of a globally distributed pest (Sitobion avenae, wheat aphid), in response to low doses of two insecticides. The first, imidacloprid shows a positive temperature coefficient; the second, beta-cypermethrin has a negative temperature coefficient. Results: Compared with the results seen with the constant temperature (22°C), a wide temperature amplitude (± 12°C) amplified the negative effects of imidacloprid on the survival, longevity, and fecundity of S. avenae, but significantly increased the early fecundity of the wheat aphid. Beta-cypermethrin positively impacted the wheat aphid at all temperature amplitudes studied. Specifically, beta-cypermethrin significantly increased the survival, longevity, and fecundity of S. avenae under medium temperature amplitude (± 6°C). There were no significant differences in the survival, longevity, and the early fecundity of S. avenae when it was treated with beta-cypermethrin at the wide temperature amplitude (± 12°C). However, the negative effect of beta-cypermethrin on the intrinsic rate of increase of S. avenae decreased gradually with the increase in temperature amplitude. Discussion: In conclusion, the response of S. avenae to positive temperature coefficient insecticides was markedly affected by temperature amplitude, while negative temperature coefficient insecticides increased the environmental adaptability of S. avenae to various temperature amplitudes. Our results highlight the importance of the integrated consideration of diurnal temperature fluctuations and different temperature coefficient insecticide interactions in climate-change-linked insecticide risk assessment; these results emphasize the need for a more fine-scale approach within the context of climate change and poison sensitivity.

Metabolomics and mass spectrometry imaging reveal the chronic toxicity of indoxacarb to adult zebrafish (Danio rerio) livers

Indoxacarb is a widely used insecticide in the prevention and control of agricultural pests, whereas its negative effects on non-target organisms remain largely unclear. Herein, we demonstrated the integrated metabolomics and mass spectrometry imaging (MSI) methods to investigate the chronic exposure toxicity of indoxacarb at environmentally relevant concentrations in adult zebrafish (Danio rerio) liver. Results showed that movement behaviors of zebrafish can be affected and catalase (CAT), glutamic oxalacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) activities were significantly increased after indoxacarb exposure for 28 days. Pathological analysis of zebrafish livers also showed that cavitation and pathological reactions occur. Metabolomics results indicated that metabolic pathways of zebrafish liver could be significantly affected by indoxacarb, such as tricarboxylic acid (TCA) cycle and various amino acid metabolisms. MSI results revealed the spatial differentiation of crucial metabolites involved in these metabolic pathways within zebrafish liver. Taken together, these integrated MSI and metabolomics results revealed that the toxicity of indoxacarb arises from metabolic pathways disturbance, which resulted in the decrease of liver detoxification ability. These findings will promote the current understanding of pesticide risks and metabolic disorders in zebrafish liver, which provide new insights into the environmental risk assessment of insecticides on aquatic organisms.

The effect of temperature on toxicokinetics and the chronic toxicity of insecticides towards Gammarus pulex

A comprehensive understanding of chemical toxicity and temperature interaction is essential to improve ecological risk assessment under climate change. However, there is only limited knowledge about the effect of temperature on the toxicity of chemicals. To fill this knowledge gap and to improve our mechanistic understanding of the influence of temperature, the current study explored toxicokinetics and the chronic toxicity effects of two insecticides, imidacloprid (IMI) and flupyradifurone (FPF), on Gammarus pulex at different temperatures (7–24 °C). In the toxicokinetics tests, organisms were exposed to IMI or FPF for 2 days and then transferred to clean water for 3 days of elimination at 7, 18, or 24 °C. In the chronic tests, organisms were exposed to the individual insecticides for 28 days at 7, 11, or 15 °C. Our research found that temperature impacted the toxicokinetics and the chronic toxicity of both IMI and FPF, while the extent of such impact differed for each insecticide. For IMI, the uptake rate and biotransformation rate increased with temperature, and mortality and food consumption inhibition was enhanced by temperature. While for FPF, the elimination rate increased with temperature at a higher rate than the increasing uptake rate, resulting in a smaller pronounced effect of temperature on mortality compared to IMI. In addition, the adverse effects of the insecticides on sublethal endpoints (food consumption and dry weight) were exacerbated by elevated temperatures. Our results highlight the importance of including temperature in the ecological risk assessment of insecticides in light of global climate change.

Determination, distribution and potential health risk assessment of insecticides and acaricides in citrus fruits of China

In this study, residues and potential health risks of 16 commonly used insecticides and acaricides in 1633 citrus samples from nine cultivars in China were systematically analyzed. A quick, easy, cheap, effective, rugged, and safe method combined with gas chromatography tandem mass spectrometry and liquid chromatography tandem mass spectrometry was applied. In total, 77.3% of the samples were with residues, of which 57.7% contained 2–12 multi-residues. Etoxazole and chlorpyrifos were the top two detected pesticides with detection frequencies of 37.1% and 31.1%, respectively. Residues of eight analytes were over their MRLs with exceeding rates of 0.1%− 2.4%. The safety of the nine cultivars ranked as lemon > pummelo > ponkan > satsuma mandarin > orange > citrus hybrids > ‘nanfengmiju’ mandarin > ‘shatangju’ mandarin > kumquat according to IqR values and related to the producing areas. Chronic dietary risks of the 16 insecticides and acaricides were negligible low for Chinese consumers. However, %ARfD of triazophos in most citrus cultivars for all population and of bifenthrin in ‘nanfengmiju’ mandarin for children were beyond the acceptable levels, which indicated potential acute health risks. Application of triazophos, bifenthrin, profenofos and etoxazole in citrus should be controlled.

Limited Scope Risk Assessment for Nontarget Ground-Dwelling Arthropods From Systemic Insecticide Applications to Young Pines.

The Nantucket pine tip moth (NPTM) [Rhyacionia frustrana (Comstock)], a native regeneration pest on young loblolly pines (Pinus taeda L.), negatively impacts pine growth. An emerging management approach is to apply systemic insecticides to seedlings to reduce NPTM damage. These systemic insecticide applications generally occur once, perhaps twice, during the first few years of loblolly pine growth. However, these applications could lead to unintended environmental consequences to nontarget organisms. The purpose of this study was to assess potential nontarget effects from four systemic insecticide applications by assessing ground-dwelling arthropod trap catch, with a focus on collembolan trap catch and genera richness. Loblolly seedlings (24 seedlings per plot) at three sites in southeast Georgia were treated with either chlorantraniliprole, dinotefuran, fipronil, or imidacloprid or left untreated as a control. Arthropods were collected with pitfall traps that were deployed for 5 d in July, August, and September 2019, 7-9 mo after treatment. Ground-dwelling arthropod trap catch, arthropod order trap catch, collembolan trap catch, and collembolan genera richness did not vary among insecticide treatments and the untreated control in this mid-term insecticide risk assessment. While no significant effects of insecticide treatment were observed, ground-dwelling arthropod trap catch, collembolan trap catch, and collembolan genera richness differed among collection times. This study was the first of its kind in a young pine stand setting and is an important first step to understanding risk in these settings. Information on nontarget risks of management practices informs growers of the level of environmental risk associated with systemic insecticides.

Short-term lab assessments and microcolonies are insufficient for the risk assessment of insecticides for bees

Risk assessment studies addressing effects of agrochemicals on bumblebees frequently use microcolonies. These are queenless colonies consisting of workers only in which typically one worker will lay unfertilized male-destined eggs. In the first tier of risk assessment for bees, short-term laboratory experiments (e.g. microcolonies) are used, the results of which will determine whether higher tier (semi-)field experiments are needed. To evaluate the suitability of microcolonies for risk assessment, a direct comparison between different assessment methods for the neonicotinoid pesticides acetamiprid and thiacloprid was made: microcolonies and queenright colonies under short-term laboratory conditions, queenright colonies under long-term laboratory conditions, and queenright colonies under field conditions. Here, we demonstrate that results from microcolonies contradict results from queenright colonies. While thiacloprid negatively impacted gyne production in queenright colonies, it had a positive effect on microcolony size. By contrast, thiacloprid had no significant effect on fitness parameters of queenright colonies under short-term laboratory conditions when mostly workers are produced. These results thus highlight both the need for long term assessments, allowing evaluation of gyne production, and the risk of reaching erroneous conclusions when using microcolonies. The negative effect of thiacloprid on colony fitness was confirmed under field conditions, where thiacloprid affected the production of reproductives, colony weight gain, worker weight, and foraging behaviour. For acetamiprid, a negative trend on colony fitness could only be shown in a field setup. Therefore, field-realistic setups, which allow colonies to forage freely, are most appropriate to assess sublethal effects of pesticides affecting behaviour and learning.

Single and combined effects of insecticides on multi-level biomarkers in the non-target amphipod Gammarus fossarum exposed to environmentally realistic levels

Aquatic media are ultimate recipients of various contaminants including pesticides pervasively applied in agrosystems. Characterizing the ecotoxicity of pesticides and their mixtures to aquatic wildlife at field-realistic levels is thus crucial for environmental risk assessment. This study aims at assessing the effects of two current-use insecticides, imidacloprid and chlorpyrifos, on Gammarus fossarum using multi-level biomarkers. In microcosms, gammarids were exposed for 72 h to insecticides tested individually or in mixture at 0.01, 0.1 and 1 μg/L of each chemical. Multi-metric responses were assessed at the individual level (behavioural traits: locomotion, respiration and amplexus formation) and the cellular level (enzymes involved in growth, moulting, digestion and cell stress). The results showed insecticide-elicited behavioural and biochemical responses from the lowest concentration of 0.01 μg/L. Overall, single exposures stimulated behavioural traits and inhibited enzymatic activities, highlighting subtle impacts at different organizational levels but these were not dose related. For binary mixtures, antagonistic effects (i.e. less-than-additive) on biomarkers were mainly observed when compared with single exposures. Multi-variable analyses indicated the complementarity of behavioural and biochemical biomarkers in identifying sublethal biological alterations and dose-dependent multiple action sites of insecticides. Besides, the mortality observed only for the mixture at 1 μg/L demonstrated a high lethal potential of insecticides in a simple binary combination. To conclude, this study demonstrates disturbances in individual performances and cellular impairments occurring at environmentally realistic exposure levels in a non-target wild species. Since the sublethal effects, such as those identified with this multi-biomarker approach, could lead to long-term alterations in population dynamics of agricultural areas, they constitute promising early endpoints for risk assessment of insecticides.

Selectivity of novel and traditional insecticides used for management of whiteflies on the parasitoid Encarsia formosa.

Encarsia formosa Gahan is the most important parasitoid exploited for the control of whitefly pests of vegetable crops. However, the non-target effects of recently developed insecticides for controlling whiteflies toward this biocontrol agent is little documented. Here we evaluated the susceptibility of E. formosa adults and juveniles to eight commonly used insecticides against whiteflies. Residual toxicity tests on glass showed that E. formosa adults were susceptible (over 98% mortality after 6h treated) to field concentrations of the tested neonicotinoids (imidacloprid, acetamiprid, nitenpyram and thiamethoxam), abamectin, cyantraniliprole, and sulfoxaflor at their field concentrations. Pyriproxyfen was harmless to both adult and pupae of E. formosa. A risk quotient analysis showed that toxicity of pyriproxyfen to E. formosa adults was the lowest, followed by acetamiprid and cyantraniliprole. In the leaf residues test, mortality of E. formosa adults under all insecticides decreased when the residue age increased. Interestingly, E. formosa experiencing contact with the residues of most insecticides, except pyriproxyfen and abamectin, parasitized significantly more hosts 5-days after treatment, suggesting a hormetic effect on parasitism. The risk assessment of insecticides indicated that pyriproxyfen and cyantraniliprole were the least toxic to E. formosa. Our results suggest that the inclusion of the insecticides in sustainable integrated pest management programs of whiteflies should be carefully evaluated on a case-by-case basis. © 2019 Society of Chemical Industry.

Acute effect of low-dose thiacloprid exposure synergised by tebuconazole in a parasitoid wasp.

Agricultural practices often involve tank-mixing and co-application of insecticides with fungicides to control crop pests. However, natural methods relying on biological control agents such as hymenopteran parasitoids have been shown to be highly effective in suppressing crop pest populations. The current body of insecticide risk assessment data accounting for fungicide co-application is very small, the present study being the first to examine this in a parasitoid wasp. Through low-dose exposure to dry residues of the neonicotinoid insecticide thiacloprid, we examined its mortal and knockdown effect on Aphelinus abdominalis when co-applied with increasing doses of the fungicide tebuconazole. Both of these acute effects of thiacloprid were synergised (toxicity increased to a greater-than-additive effect) by tebuconazole, resulting in significant mortality from low-dose co-applications of tebuconazole, and significant knockdown even without co-applied tebuconazole, the effect increasing as tebuconazole concentration increased. We show the highly toxic effect that a low dose of thiacloprid imposes on A. abdominalis populations, and a synergistic toxicity when co-applied with low doses of tebuconazole. Our work suggests a need for updating pesticide risk assessment methods, accounting for pesticide mixtures, in order to make these risk assessments more field relevant.

Detection of oxidative stress and DNA damage in freshwater snail Lymnea leuteola exposed to profenofos

Extensive production and use of organophosphate pesticide in agriculture, has risen concerned about its ecotoxicity and risk assessment of insecticides, which are more important. Therefore, the present investigation was aimed to study the induction of oxidative stress and DNA damage by organophosphate insecticide profenofos (PFF) in freshwater snail Lymnea luteola (L. luteola). The median lethal value (96 h LC50) of PFF was estimated as 1.26 mg/L for L. luteola in a semi-static system and on the basis of LC50 value three concentrations viz., 0.126 (1/10 of LC50, Sublethal I), 0.63 (1/2 of LC50, Sublethal II) and 0.84 mg/L (2/3 of LC50, Sublethal III) were determined. Snails were exposed to above-mentioned concentrations of PFF along with solvent control (acetone) and negative control for 96 h. The haemolymph was collected at 24 and 96 h of after treatment. In heamolymph of PFF exposed snail, lipid peroxide, glutathione reduced glutathione S transferase and superoxide dismutase activities at the tested concentrations significantly differ from those in the control. The genotoxicity induced in hemocytes of treated snails was measured by alkaline single cell gel electrophoresis assay. The data of this experiment demonstrated significantly enhancement of oxidative stress and DNA damage in the treated snails as compared to controls. Also, we observed statistically significant correlations of ROS with DNA damage (% tail DNA) (R2 = 0.9708) for 24 h and DNA damage (R2 = 0.9665) for 96 h. Results of the current experiment can be useful in risk evaluation of PFF among aquatic organisms. The study confirmed the use of comet assay for in vivo laboratory experiments using freshwater snail for selecting the toxic potential of industrial chemicals and environmental contaminants.

An exposure-based, ecology-driven framework for selection of indicator species for insecticide risk assessment

In the current “tiered” paradigm for evaluating risks of insecticidal products, one of the first decisions that must be made is the selection of indicator species to be used in toxicity assays. However, as yet, no formal system has been developed to determine whether proposed indicator species are relevant to the ecology of the crop system where the product will be released. Here, we propose a protocol that provides information on the ecology and trophic linkages of organisms within agro-ecosystems, and demonstrate its implementation within maize agro-ecosystems, which have been a major focus of recent insecticidal developments. We use molecular gut-content assays and network analysis to identify species that are likely to be exposed to plant-incorporated products, and that likely have important functional roles in interaction webs in the maize ecosystem. The vast majority of arthropod abundance was found in the soil (97% of specimens per m2 were found in the soil column). Only nine of the 382 morphotaxa met all three of the ecological criteria (high abundance, corn consumption, degree of connectedness within the network) for inclusion as indicator species, only one of which, Orius insidiosus (Say) (Hemiptera: Anthocoridae), has routinely been considered in risk assessment. Ecological data collected in studies such as this one can be used to ensure that insecticide risk assessments are ecologically relevant. We advocate the use of large-scale field bio-inventories, combined with molecular gut-content assays and ecological network analysis as regular components of the preparation and design phases of all future risk-assessment programs.

Sublethal effects of four synthetic insecticides on the generalist predator Cyrtorhinus lividipennis

Cyrtorhinus lividipennis Reuter, an important predator of rice planthopper and leafhoppers, plays a significant role in the integrated pest management (IPM) of rice pest. However, chemical control remains a major strategy against rice pests. Insecticide risk assessment should include sublethal effects on non-target organisms before being included in IPM schemes. We examined the sublethal effects of four insecticides, triazophos, deltamethrin, chlorantraniliprole, and pymetrozine on C. lividipennis. The results demonstrated that sublethal concentrations of deltamethrin (LC20 and LC10) disrupted the orientation behavior of C. lividipennis, but sublethal concentrations of triazophos (LC20 and LC10), chlorantraniliprole, and pymetrozine (the recommended field rate and half field rate) had no impact on the behavioral response of surviving predators. The mean consumption of C. lividipennis treated with sublethal concentrations of triazophos decreased approximately 18–35 % compared to that of untreated ones. Sublethal concentrations of deltamethrin also reduced the mean consumption of C. lividipennis, but sublethal concentrations of chlorantraniliprole and pymetrozine exhibited no influence on the predatory capability of the predator. Significant reductions in pepsin activity were observed in triazophos and deltamethrin treatments but not in chlorantraniliprole and pymetrozine treatments. Our results indicated that triazophos and deltamethrin exerted sublethal effects, such as disturbed foraging ability, reduced predatory capacity, and decreased pepsin activity on C. lividipennis, and chlorantraniliprole and pymetrozine were regarded as safer to this predator.

Does insecticide drift adversely affect grasshoppers (Orthoptera: Saltatoria) in field margins? A case study combining laboratory acute toxicity testing with field monitoring data

The current terrestrial risk assessment of insecticides regarding nontarget arthropods considers exclusively beneficial organisms, whereas herbivorous insects, such as grasshoppers, are ignored. However, grasshoppers living in field margins or meadows adjacent to crops may potentially be exposed to insecticides due to contact with or ingestion of contaminated food. Therefore, the present study assessed effects of five active ingredients of insecticides (dimethoate, pirimicarb, imidacloprid, lambda-cyhalothrin, and deltamethrin) on the survival of Chorthippus sp. grasshopper nymphs by considering two routes of exposure (contact and oral). The experiments were accompanied by monitoring field margins that neighbored cereals, vineyards, and orchards. Grasslands were used as reference sites. The laboratory toxicity tests revealed a sensitivity of grasshoppers with regard to the insecticides tested in the present study similar to that of the standard test species used in arthropod risk assessments. In the field monitoring program, increasing grasshopper densities were detected with increasing field margin width next to cereals and vineyards, but densities remained low over the whole range of field margins from 0.5 to 20 m next to orchards. Grasshopper densities equivalent to those of grassland sites were only observed in field margins exceeding 9 m in width, except for field margins next to orchards. These results may indicate that current insecticide risk assessments are insufficiently protective for grasshoppers in field margins.

Erratum to: A two-dimensional probabilistic acute human-health risk assessment of insecticide exposure after adult mosquito management

Ultra-low-volume (ULV) aerosol applications of insecticides are used to manage high densities of adult mosquitoes. We used two-dimensional probabilistic risk assessment methodologies to evaluate three pyrethroid insecticides (phenothrin, resmethrin, and permethrin), pyrethrins, and two organophosphate insecticides (malathion and naled), applied by truck-mounted ULV sprayer. Piperonyl butoxide, a synergist commonly used in pyrethroid and pyrethrins formulations, was also assessed. The objective of our study was to evaluate probabilistically if a deterministic human-health risk assessment of mosquito insecticides was sufficiently conservative to protect human-health. Toddlers and infants were the highest risk groups while adult males were the lowest risk group assessed in this study. Total acute exposure ranged from 0.00003 to 0.0003 mg/kg day−1 for the chemicals and subgroups assessed examining inhalation, dermal, oral, and hand-to-mouth exposure. We used the risk quotient (RQ) method for our risk assessment, which is calculated by dividing the total potential exposure for each subgroup and chemical by its ingestion toxic endpoint value (RfD). Mean RQs ranged from 0.000004 to 0.034 for all subgroups and chemicals, with none exceeding the RQ level of concern. Naled had the highest RQs of any chemical assessed while PBO had the lowest. Sensitivity analysis demonstrated that the exposure from inhalation and deposition contributed the largest variance to the model output. Results support the findings of previous studies that the risks from adult mosquito management are most likely negligible, and that the human-health deterministic risk assessment is most likely sufficiently conservative.

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Most insecticides are nerve poisons. Organochlorines and pyrethroids affect the nerve membranes and induce electrophysiological effects; organophosphates and carbamates inhibit acetylcholinesterases; nicotine, nereistoxins and chlornicotinyl insecticides affect acetylcholine receptors; avermectins affect GABA receptors; and attractants, repellents, antifeedants and pheromones affect sensory organs. Toxins of Bacillus thuringiensis affect the insect mid gut; organofluorids and arsenates affect energy production; rotenone, dinitrophenols and HCN inhibit respiratory mechanisms; and benzoylphenylureas, buprofezin and JH mimics affect insect growth. These classifications are based on the target and primary action of the compounds. A mode of action study should include definitive information of the sequential processes that lead to death of the animal. These are highly complicated processes and effects of the primary, secondary, tertiary, etc. actions on the intact animal should be considered. Few entomologists studied insect toxicology before the 2nd World War. Successful progress in insect toxicology has been stimulated by the development of insect physiology, insect biochemistry, radio tracer techniques, chromatography, electrophysiology, etc. along with the collaborated development of new synthetic insecticides. Risk assessment of insecticides has been performed not only by evaluation of acute toxicity but also chronic toxicity, carcinogenecity, mutagenecity and propagation by Good Laboratory Practices, environmental assessment, etc. Safeties of insecticides were assured by insecticide registration laws. However, the risk assessment of insecticides seems to be unsatisfactory from the view point of endocrine disruption. Mode of action of endocrine disruption compounds is so complicated that experiments on the mode of action of these compounds must cover many related organs and physiological actions through successive generations. As we cite in this review, a report was withdrawn or others have objections. These show how difficult to draw conclusions on endocrine disruption of compounds. Regarding risk assessment of insecticides, we must carefully discuss data in a realistic and science-based manner.