Insecticide Mixtures Research Articles

Associations between Neonicotinoid, Pyrethroid, and Organophosphate Insecticide Metabolites and Neurobehavioral Performance in Ecuadorian Adolescents.

Organophosphate and pyrethroid insecticides can affect children's neurodevelopment and increase inflammation. Limited evidence exists among adolescents and on whether inflammation may mediate pesticide-neurobehavior associations. We examined the associations between insecticide metabolite concentrations and neurobehavior among adolescents in Ecuadorian agricultural communities. We included 520 participants aged 11-17 years. We measured urinary insecticide metabolites (mass spectrometry) and neurobehavior (NEPSY-II). Associations were adjusted for socio-demographic and anthropometric characteristics. The associations of insecticide mixtures with neurobehavior were evaluated using PLS regression, and mediation by inflammatory biomarkers (TNF-α, IL-6, CRP, SAA, sICAM-1, sVCAM-1 and sCD-14) was conducted. Among organophosphates, para-nitrophenol (PNP) and 3,5,6-Trichloro-2-pyridinol (TCPy) were inversely associated with Social Perception (score difference per 50% increase [β 50% ] = -0.26 [95%CI: - 1.07, -0.20] and -0.10 [-0.22, 0.01], respectively). PNP and TCPy also had significant inverse associations with Attention/Inhibitory Control at concentrations >60 th percentile (β 50% = -0.26 [95%CI: -0.51, -0.01] and β 50% = -0.22 [95%CI: -0.43, -0.00], respectively). The pyrethroid, 3-phenoxybenzoic acid (3-PBA), was inversely associated with Language (β 50% = -0.13 [95%CI: -0.19, -0.01]) and had a negative quadratic association with Attention/Inhibitory Control. The neonicotinoid 5-Hydroxy imidacloprid (OHIM) was positively associated with Memory/Learning (β 50% = 0.20 [95%CI: 0.04, 0.37]). Mixtures of all insecticides were significantly negatively related to all domains, except for Memory/Learning, which was positively associated. No mediation by inflammatory markers on these associations was observed. Concurrent organophosphate, pyrethroid, and the mixtures of all metabolites were associated with lower performance in all domains except for Memory/Learning. Neonicotinoids were positively associated with Memory/Learning and Social Perception scores.

Toxicity of pesticide cocktails in amphibian larvae: understanding the impact of agricultural activity on aquatic ecosystems in the Salado River basin, Argentina

Aquatic communities are increasingly exposed to complex mixtures of contaminants, mainly pesticides due to the impact of agricultural activity. The aim of this study was to evaluate the toxicity of an eight-pesticide cocktail on larvae of the South American common toad, Rinella arenarum. The cocktail represents a realistic mixture of insecticides (cypermethrin, chlorpyrifos and lambda-cyhalothrin), herbicides (glyphosate, glufosinate ammonium, prometryn and metolachlor), and a fungicide (pyraclostrobin) previously found in aquatic organisms (Prochilodus lineatus) from the Salado River Basin, an area with strong agricultural pressure. Computational simulations through the Density Functional Tight-Binding method indicated a strong spontaneous trend toward the formation of the cocktail, suggesting that it may act as a novel xenobiotic entity in the environment. The cocktail effects were evaluated in early-developing and premetamorphic larvae, at feasible concentrations found in real scenarios. The mixture led to high mortality and teratogenicity in early-developing larvae. Premetamorphic larvae showed endocrine disruption, oxidative stress, and impairments in detoxification and hepatic functioning. Neurotoxicity, genotoxicity, cardiotoxicity and high mortality under stress conditions were also observed in exposed larvae. This novel evaluation highlights the ecotoxicological risk for aquatic organisms exposed to complex mixtures and underscores the need to consider cocktail effects in studies regarding ecosystems health.

Effects of the insecticide acetamiprid and the fungicide azoxystrobin on locomotion activity and mushroom bodies of solitary bee Centris analis

Pesticide use is a major factor contributing to the global decline in bee populations. Sublethal effects, such as behavior alterations, are neglected in pesticide regulation for pollinators. However, these effects can bring important information to understanding the impacts of pesticides on bees' daily activities. In this study, we aimed to investigate the effects of the insecticide acetamiprid (7 ng/μL) and the fungicide azoxystrobin (10 ng/μL) on the behavior of the Neotropical solitary bee Centris analis. Female and male bees were exposed to these chemicals continuously for 48 h, followed by an additional 48 h without contaminated food, totaling 96 h of observation. We used five experimental groups: control, solvent control, insecticide, fungicide, and pesticide mixture (insecticide + fungicide). Behavioral alterations based on locomotion and light response were assessed by video tracking at 48 (end of pesticide exposure) and 96 h (end of bioassay). In addition, after recording bees at 96 h, the individuals were anesthetized for brain collection and histological evaluation of mushroom bodies to evaluate if pesticides can damage their neurons and impair the cognitive processes and responses of bees to sensory stimuli. Bees exposed to acetamiprid and pesticide mixture showed lethargic movements and impaired locomotion at 48 h. Notably, these behavioral effects were no longer evident after the bees consumed uncontaminated food for an additional 48 h, totaling 96 h from the start of pesticide exposure. Only fungicide exposure did not result in any behavioral or brain histological changes. Therefore, our study showed that acetamiprid at an estimated residual concentration, despite being classified as having low toxicity for bees, can cause significant initial locomotion disruption in solitary bees. These findings highlight the importance of considering sublethal effects in environmental risk assessment.

The interplay between temperature and an insecticide mixture modulates the stimulatory response of sublethally exposed Myzus persicae.

Temperature can interact with chemical pesticides and modulate their toxicity. Sublethal exposure to pesticides is known to trigger hormetic responses in pests. However, the simultaneous effects of temperature and sublethal exposure to single or mixture-based insecticides on the insects' stimulatory responses are not frequently considered in toxicological studies. Here we investigated the combined effects of temperature on the lethal and sublethal responses of the green peach aphid Myzus persicae after exposure to commercial formulations of a neonicotinoid (thiamethoxam) and a pyrethroid (lambda-cyhalothrin) and their mixture. Firstly, the concentration-response curves of the insecticides were determined under four temperatures (15 °C, 20 °C, 25 °C, and 28 °C) by the leaf dipping method. Subsequently, the sublethal concentrations C0, CL1, CL5, CL10, CL15, CL20, and CL30 were selected to assess sublethal effects on aphids' longevity and reproduction under the same temperatures. The results showed that the mixture of thiamethoxam + lambda-cyhalothrin caused greater toxicity to aphids compared to the formulations with each active ingredient alone and that the toxicity was higher at elevated temperatures. Furthermore, the exposure to low concentrations of the mixture (thiamethoxam + lambda-cyhalothrin) and the separated insecticides induced stimulatory responses in the longevity and fecundity of exposed aphid females, but the occurrence of such hormetic responses depended on the insecticide type, its sublethal concentration, and the temperature as well as their interactions.

Field-evolved resistance to nitenpyram is associated with fitness costs in whitefly.

Elucidating fitness cost associated with field-evolved insect resistance to insecticide is of particular importance to current sustainable pest control. The global pest whitefly Bemisia tabaci has developed resistance to many members of neonicotinoids, but little is known about whitefly resistance to neonicotinoid nitenpyram and its associated fitness cost. Using insecticide bioassay and life-table approach, this study aims to investigate nitenpyram resistance status in field-collected whitefly populations, and to explore whether such resistance is accompanied by a fitness cost. The bioassay results revealed that 14 of 29 whitefly populations displayed moderate to extremely high resistance to nitenpyram, demonstrating a widespread field-evolved resistance to nitenpyram. This field-evolved resistance in the whitefly has increased gradually over the past 3 years from 2021 to 2023. Further life-table study showed that two resistant whitefly populations exhibited longer developmental time, shorter lifespans of adult, and lower fecundity compared with the most susceptible population. The relative fitness cost of the two resistant populations was calculated as 0.69 and 0.56 by using net productive rate R0, which suggests that nitenpyram resistance comes with fitness cost in the whitefly, especially on reproduction. Overall, these results represent field-evolved high resistance to nitenpyram in the whitefly. The existing fitness costs associated with nitenpyram resistance are helpful to propose a suitable strategy for sustainable control of whiteflies by rotation or mixture of insecticide with different modes of action. © 2024 Society of Chemical Industry.

Theory versus practice: are insecticide mixtures in Arizona cotton used for resistance management?

Resistance management in pesticide use is critical, yet grower practices, especially pesticide mixing motivations, diverge from theoretical frameworks. This study analyzes 30 years of Arizona cotton growers' practices and pest manager insights to understand mixing trends. Growers predominantly mix pesticides for spectrum or efficacy, not resistance management. This highlights a gap between theory and practice, emphasizing the complexity of real-world dynamics. A shift over time towards selective insecticides and integrated pest management (IPM), supported by extension education, has reduced reliance on broad-spectrum insecticides and increased opportunities to conserve the natural enemies of key pests. This reduced the frequency of insecticide use, a mutual goal of both IPM and resistance management. The availability and adoption of selective products with diverse modes of action, along with the resulting increases in biological control and refuges, likely has delayed or prevented resistances without emphasis on using mixtures specifically for resistance management. In a disrupted system exclusively dependent on broad-spectrum insecticides (1991-1995), 75% ± 5% of cotton area was sprayed with mixtures of these materials. With the availability of selective insecticides, few broad-spectrum products are used today and mixtures of insecticides are sprayed on only 36% ± 3% of the cotton area (2015-2020). Although mixing has theoretical relevance, it is diminishing in stable systems with diverse modes of action and adherence to moderation principles. Arizona cotton guidance prioritizes multi-crop refuges over mixtures for resistance management. Integrated research and education, targeting professional pest managers, are pivotal in advancing resistance management without mixtures specifically designed to prevent or mitigate resistance. © 2024 Society of Chemical Industry.

Pesticide Translocation Using Nonpressurized and Pressurized Endotherapeutic Treatments in Coconut Palms

Coconut cultivation faces serious challenges caused by pests and diseases, whose targets are often not reached by conventional application methods such as spraying and soil application. New control strategies, such as vegetative endotherapy, have emerged, but knowledge gaps persist regarding many aspects, especially in pesticide translocation within palm trees, which is crucial for an efficient practical field application. This study investigated the translocation of a mixture of commercial insecticides and fungicides—difenoconazole, imidacloprid, thiabendazole, cyproconazole, thiamethoxam, spirodiclofen, and carbosulfan—applied via pressurized and nonpressurized endotherapeutic methods to coconut stems. This assessment aimed to quantify the concentrations of pesticide translocation through the stem, from the application site to the plant canopy. Due to the difficulty of applying the solution to the instrument used for pressurized endotherapy, the solution had to be diluted and used at a lower volume. In experimental field conditions, stem samples were assessed at 50 and 100 cm above the application point following endotherapy treatments conducted over a period ranging from 2 to 45 days. The analyses were performed using LC-MS/MS. In the pressurized method, the highest concentrations were observed for difenoconazole (1684 µg kg−1), imidacloprid (1278 µg kg−1), and thiabendazole (781 µg kg−1). Conversely, in the nonpressurized method, the highest concentrations were recorded for imidacloprid (5803 µg kg−1), followed by difenoconazole (3660 µg kg−1) and thiabendazole (2598 µg kg−1). To address the issue with formulation conditions in the pressurized method and to allow a comparison between the two application methods, we simulated extrapolated results for comparison with the nonpressurized method. This evaluation aimed to evaluate both methods under similar formulation conditions (volume and concentration). The results predicted that if the solution had not been diluted, the pressurized method would present the best translocations, mainly near the plant canopy, except for carbofuran. All pesticides were translocated independently of their physical–chemical properties or formulation. No pesticide residues were detected in the coconut water and pulp up to 120 days after the endotherapy application.

Transgenerational effect of a tea saponin–matrine mixture promotes fecundity and alters associated bacteria in the fall armyworm Spodoptera frugiperda

The fall armyworm Spodoptera frugiperda is a one of the most invasive and damaging pests that causes serious economic losses in several crops. Botanical insecticides such as tea saponin and matrine, as environmentally acceptable biopesticides, are widely used for controlling pests. Insecticide stress affects both individuals and the associated bacteria in insects. However, it remains unclear that if sublethal effects and bacteria are the drivers for the adaptive mechanisms of insecticides in fall armyworm. We examined the effectiveness of a 10:1 v/v mixture of biological insecticides against the fall armyworm and the impacts of several biological parameters and demographic variables of the armyworm targeting two generations at primary exposure. Moreover, the influence of the insecticide mixture on the associated bacteria of the fall armyworm was assessed via 16 S rRNA sequencing. The results showed that the mixture was highly toxic to fall armyworms, and the fecundity of the initially exposed generation (F0) significantly decreased; however, there was no significant effect on longevity. The larval duration, the total pre-reproductive period, longevity, fecundity, and mean generation time of the fall armyworm in the F1 significantly increased; yet the intrinsic and finite rates of the increase and the net reproductive rate remained fairly constant. Additionally, the population of associated bacteria was affected in both generations, with an increase in the microbial diversity within the fall armyworm compared to that of the F0 generation. Also, an increase in abundance of several genera of bacteria, including Acinetobacter, Serratia, Enterococcus, and Pseudomonas, was noted following treatment with the insecticide mixture. These results broaden our understanding of the impact of sublethal insecticide concentrations on the fall armyworm and its associated bacterial community.

Behavioral responses and life history traits of Taiwanese and Indonesian populations of Aedes aegypti surviving deltamethrin–clothianidin treatment

BackgroundIndoor residual spraying (IRS) capitalizes on the natural behavior of mosquitoes because Aedes aegypti commonly seeks indoor resting sites after a blood meal. This behavior allows mosquitoes to be exposed to insecticide-treated surfaces and subsequently killed. Combinations of deltamethrin and clothianidin with different modes of action have shown promise in IRS, effectively targeting both susceptible and pyrethroid-resistant malaria vectors. However, the effects of this approach on Aedes mosquitoes remain unclear. The present study tested the effects of deltamethrin–clothianidin mixture treatment on behavioral responses and life history traits of Taiwanese and Indonesian populations of Ae. aegypti.MethodsWe adopted an excito-repellent approach to explore the behavioral responses of pyrethroid-resistant Ae. aegypti populations from Indonesia and Taiwan to a deltamethrin–clothianidin mixture used in contact irritancy and non-contact repellency treatments. We further evaluated the life history traits of surviving mosquitoes (i.e., delayed mortality after 7-day post-treatment, longevity, fecundity, and egg hatching) and investigated the potential transgenerational hormetic effects of insecticide exposure (i.e., development rate and survival of immatures and adult mosquitos).ResultsAll tested field populations of Ae. aegypti displayed strong contact irritancy responses; the percentage of escape upon insecticide exposure ranged from 38.8% to 84.7%. However, repellent effects were limited, with the escape percentage ranging from 4.3% to 48.9%. We did not observe immediate knockdown or mortality after 24 h, and less than 15% of the mosquitoes exhibited delayed mortality after a 7-day exposure period. However, the carryover effects of insecticide exposure on the survival of immature mosquitoes resulted in approximately 25% higher immature mortality than that in the control. By contrast, we further documented stimulated survivor reproduction and accelerated transgenerational immature development resulting from the sublethal effects of the insecticide mixture. In particular, the number of eggs laid by treated (both treatments) female mosquitoes increased by at least 60% compared with that of eggs laid by control female mosquitoes.ConclusionsIRS with deltamethrin–clothianidin effectively deters Aedes mosquitoes from entering residential areas and thereby reduces mosquito bites. However, the application rate (deltamethrin: 25 mg/m2; clothianidin: 200 mg/m2) may be insufficient to effectively kill Aedes mosquitoes. Insecticide response appears to vary across mosquito species; their behavioral and physiological responses to sublethal doses have crucial implications for mosquito control programs.Graphical

Insecticide mixtures-uses, benefits and considerations.

Insecticides remain an important tool for the control of many insect pests. There has long been an interest in insecticide mixtures (in-can and tank-mix) as a means to provide the needed efficacy and/or spectrum to control many insect public health, crop pests or crop pest complexes. This aspect has become more important since insecticides developed in the last 30 years tend to be narrower in spectrum with many primarily focused on either sap-feeding or chewing insect pests. Insecticide mixtures are also seen as an important approach to insect resistance management (IRM) with certain requirements for optimal implementation. Additionally, insecticide mixtures can also address certain agronomic, commercial and intellectual property needs and opportunities. This perspective will review some of the drivers and considerations for insecticide mixtures and their potential uses. © 2024 Society of Chemical Industry.

Managing of Spring Barley Fungal Spot Blotch Disease Under the Basic, Intensive and High Intensive Cultivation Technologies in Moscow

Spring barley (Hordeum vulgare L.), is one of the fourth largest grain in the world but insects, weeds and diseases agents lead to crop losses and declination of incomes. Fungal diseases cause serious losses in spring barley prompting the need to find an effective strategy of control. In the quest to find a suitable strategy, application of three treatments, high intensive, intensive and basic. In 2020, varieties (factor A) of spring barley were grown: Elf, Yaromir and Vladimir, which were placed in experimental variants that differed in the level of application of mineral fertilizers and plant protection products-basic, intensive and high-intensity technologies (factor B). We studied seeding rates - 4, 5 and 6 million germinating grains per hectare. The technology used modern drugs from Keminova), involving the application of fungicides and fertilizer compounds were evaluated for the control of fore critical fungal disease such as Spot blotch (Bipolaris sorokiniana) disease spring barley varieties Elf, Yaromir and Vladimir. The outcome of the experiment shows that the basic technology treatment with fertilizers and mixture of herbicide, insecticide and fungicides compounds were the most effective strategy in controlling the fungal Spot blotch disease, weeds, insects and increasing the yields of three varieties Elf, Yaromir and Vladimir, which was used only in autumn spring defense is forecast. The yield in the intensive treatments was close in value, respectively, 10.47 T/ha, 10.27 T/ha and 9.15 T/ha which is higher by 27%, 21% and 33 % compared to basic treatments. The outcome was reflected in the segments of the grain yield, with the end goal that the weight and mass of 1000 part were improved in three therapies contrasted with fundamental since the high escalated application was more compelling in such manner. The 3 treatments such as, high intensive, intensive and basic technologies (factor B) on three spring barley varieties (Factor-A), to control fungal disease in three replicated factorial in randomized complete block design (RCBD) containing net plot size i.e. 2 m × 5 m (10 m2). The experiments were fulfillment during the 2020 years and impact of the 3 diverse mixed protection basic, intensive and high intensive technologies were tried.

Compatibility of Metarhizium sp. (M201-NL strain) in Insecticide and Herbicide Mixtures

Field application of Metarhizium to control Oryctes rhinoceros in oil palm plantations may be overlapped with pesticides (insecticide and herbicide) spray. These chemicals may harm the fungus leading to poor virulence. This paper, however, shows that Metarhizium sp. M201-NL strain may react differently against some pesticides tested using poisoning media method. In the first experiment, the growth of mycelium of the Metarhizium sp. was observed in plated media mixed with insecticide. The highest mycelium radial growth was Fipronil 0.15 % (51.9 mm) which was not significantly different compared to the control, without insecticide (52.2 mm). However, suppression of growth of mycelium was observed in other insecticides. The radial growth of mycelium was significantly lower compared to the control if either Ethiprol, Lambdha cyhalothrin or Acephate was applied at 14 DAI. The second separate experiment involved herbicides. It was found that some herbicides did not inhibit the radial growth of mycelium. These include Metsulfuron-methyl 0.098 % (84.0 mm), Metsulfuron-methyl 0.19 % (82.75 mm), Glyphosate 19.6 % (82.5 mm), Glyphosate 9.8 % (81.6 mm) and Metsulfuron-methyl 0.39 % (80.37 mm) which were not significantly different compared to control, without herbicide (86.12 mm) at 21 DAI. In contrast, the growth of mycelium was significantly retarded when Paraquat, Triclopyr, Glyphosate, and 2.4-D was applied separately. Further study was undertaken to observe sporulation and virulence (bioassay) of the treated mycelium. The sporulations of mycelium treated with Fipronil 0.15 % or Metsulfuron-methyl of different concentrations were not statistically different to control. Similar results were also shown from bioassay. The infection rates of O. rhinoceros larva treated with mixtures of Metarhizium sp. spores with either Fipronil or Metsulfuron-methyl were insignificantly different compared to the control.

What is the value of rotations to insecticide resistance management?

Rotations have been the cornerstone of insecticide resistance management for many decades. In recent years, there has been a resurgence of interest in the use of insecticide mixtures, particularly based on new theoretical models. Here, we present a perspective on the value of rotations to insecticide resistance management, focusing on the interpretation of influential theoretical models. The principles of resistance management have previously been reduced to moderation, saturation and multiple attack. Alongside mixtures and mosaics, rotations have been presented as a strategy of multiple attack in using more than one insecticide. Three explanations have been offered for how rotations delay resistance evolution: counterselection from resistance cost, the relaxation of selection and intergenerational redundant kill. We show that all three explanations can make sense of the comparison of rotations with another resistance-management strategy but have failed to elucidate the principle at work. Overall, we argue that rotations work by moderation, delaying resistance to insecticides through the use of each insecticide less over time. We suggest that the principles of resistance management are recast as moderation, saturation and redundancy. When rotations and mixtures are not conceptualised as competing methods of multiple attack, these strategies can more obviously work together through the complementary principles of moderation and redundancy. Whether solo products or a mixture of products are used, rotations are an effective method of risk management, preserving the arsenal of all effective insecticides for longer. A successful resistance-management plan should make appropriate use of all the principles of resistance management. © 2024 Society of Chemical Industry.

Piperonylbutoxide and the Necessity of Toxicological Assessment of Insecticide Mixtures; a Letter to Editor.

Piperonylbutoxide and the Necessity of Toxicological Assessment of Insecticide Mixtures; a Letter to Editor.

Binary mixtures of imidacloprid and thiamethoxam do not appear to cause additive toxicity in fathead minnow larvae (Pimephales promelas).

Introduction: Considerable use of neonicotinoid insecticides has resulted in their detection in surface waters globally, with imidacloprid (IM) and thiamethoxam (TM) frequently found together. Neonicotinoids are selective agonists for invertebrate nicotinic acetylcholine receptors (nAChR) leading to paralysis and death. While not overtly toxic to vertebrates, growing evidence suggests that chronic exposure to individual neonicotinoids can cause adverse health effects in fish. This work examined whether chronic exposure to binary mixtures of imidacloprid (IM) and thiamethoxam (TM) would be more toxic to fathead minnow (Pimephales promelas) larvae than either insecticide alone. Materials and Methods: Embryos were exposed to a 1:1 mixture of IM and TM (0.2, 2, 20, 200 or 2,000μg/L of each pesticide) or a 1:5, 1:10, or 1:20 mixture of IM and TM (0.02μg/L of IM with 0.1, 0.2, or 0.4μg/L of TM) for a total of 8days. Survival, developmental toxicity, embryonic motor activity, and startle escape responses were quantified. Results: Survival and growth were reduced, and hatching induced by exposure to a 1:1 mixture containing > 2μg/L of each insecticide, but not following exposure to mixtures containing environmentally-relevant concentrations. Acute exposure to a 1:1 mixture did not alter embryonic motor activity; however, chronic exposure to these mixtures resulted in a slight but significant decrease in embryonic movements. Only 1:1 mixtures of high concentrations of IM and TM altered the startle escape response by increasing latency of response; however, a significant proportion of fish exposed to 1:1 mixtures had altered latency and burst speed. Taken together, these behavioral indicators of nAChR activation suggest that in mixtures, neonicotinoids could interfere with nAChR signaling despite their low affinity for the nAChR. Conclusion: Our findings suggest that toxicity of binary mixtures of IM and TM is primarily driven by IM, and that mixtures of IM with TM do not appear to cause significant additive toxicity when compared with our previous studies evaluating each neonicotinoid alone. Given the limited toxicological data available for mixtures of neonicotinoid insecticides in fish, further study is required to better understand the ecological risks these insecticides may pose to aquatic ecosystems.

Association of Prenatal Exposure to Organophosphate, Pyrethroid, and Neonicotinoid Insecticides with Child Neurodevelopment at 2 Years of Age: A Prospective Cohort Study.

Widespread insecticide exposure might be a risk factor for neurodevelopment of our children, but few studies examined the mixture effect of maternal coexposure to organophosphate insecticides (OPPs), pyrethroids (PYRs), and neonicotinoid insecticides (NNIs) during pregnancy on child neurodevelopment, and critical windows of exposure are unknown. We aimed to evaluate the association of prenatal exposure to multiple insecticides with children's neurodevelopment and to identify critical windows of the exposure. Pregnant women were recruited into a prospective birth cohort study in Wuhan, China, from 2014-2017. Eight metabolites of OPPs (mOPPs), three metabolites of PYRs (mPYRs), and nine metabolites of NNIs (mNNIs) were measured in 3,123 urine samples collected at their first, second, and third trimesters. Children's neurodevelopment [mental development index (MDI) and psychomotor development index (PDI)] was assessed using the Bayley Scales of Infant Development at 2 years of age (). Multivariate linear regression models, generalized estimating equation models, and weighted quantile sum (WQS) regression were used to estimate the association between the insecticide metabolites and Bayley scores. Potential sex-specific associations were also examined. Single chemical analysis suggested higher urinary concentrations of some insecticide metabolites at the first trimester were significantly associated with lower MDI and PDI scores, and the associations were more prominent among boys. Each 1-unit increase in ln-transformed urinary concentrations of two mOPPs, 3,5,6-trichloro-2-pyridinol and 4-nitrophenol, was associated with a decrease of 3.16 points [95% confidence interval (CI): , ] and 3.06 points (95% CI: , ) respectively in boys' MDI scores. Each 1-unit increase in that of trans-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (trans-DCCA; an mPYR) was significantly associated with a decrease of 2.24 points (95% CI: , ) in boys' MDI scores and 1.90 points (95% CI: , ) in boys' PDI scores, respectively. Significantly positive associations of maternal urinary biomarker concentrations [e.g., dimethyl phosphate (a nonspecific mOPP) and desmethyl-clothianidin (a relatively specific mNNI)] with child neurodevelopment were also observed. Using repeated holdout validation, a 1-quartile increase in the WQS index of the insecticide mixture (in the negative direction) at the first trimester was significantly associated with a decrease of 3.02 points (95% CI: , ) in MDI scores among the boys, and trans-DCCA contributed the most to the association (18%). Prenatal exposure to higher levels of certain insecticides and their mixture were associated with lower Bayley scores in children, particularly in boys. Early pregnancy may be a sensitive window for such an effect. Future studies are needed to confirm our findings. https://doi.org/10.1289/EHP12097.

Effectiveness and durability of insecticide mixtures for pyrethroid resistance in sub-Saharan Africa

Effectiveness and durability of insecticide mixtures for pyrethroid resistance in sub-Saharan Africa

Toxicity of Calophyllum soulattri, Piper aduncum, Sesamum indicum and their potential mixture for control Spodoptera frugiperda

Abstract Spodoptera frugiperda caused severe damage to the maize plant. Botanical insecticides are a choice to control this pest. This study aims to determine the ethanol extract of Calophyllum soulattri stem bark, methanol extract of Piper aduncum fruit, and Sesamum indicum oil, and their potential mixture for controlling S. frugiperda. The bioassays were carried out in laboratory conditions using second instar S. frugiperda larvae from mass rearing in the laboratory. A toxicity test was performed using the leaf-residual feeding method. The result showed that the mortality of S. frugiperda for C. soulattri is LC50 = 0.349% and LC95 = 3.256% and that for P. aduncum is LC50 = 0.530% and LC95 = 4.666%. S. indicum oil (at 10% concentration) only caused the mortality of S. frugiperda by 27.5%. Insecticide mixture can increase the toxicity of the insecticide. The observation mortality of S. frugiperda for C. soulattri and P. aduncum (1:2) extracts mixture were LC50 = 0.233% and LC95 = 0.808%. At the same time, C. soulattri extract dan S. indicum oil mixture (4:1) were LC50 = 0.268% and LC95 = 0.931%. The treatments with a single insecticide and their mixtures affected the biological activity of S. frugiperda by reducing the area of feed consumption, and the longer the larval development time, the lower the pupal weight of S. frugiperda. Our findings indicated that a mixture of C. soulattri and P. aduncum extract, then C. soulattri extract, and S. indicum oil could potentially develop as effective insecticide for controlling S. frugiperda.

Insecticides for corn leafhopper management versus entomopathogenic fungal isolates: In vitro compatibility, physical-chemical interactions, and on-farm assessments

This study is the first investigation of the biological compatibility of isolates IBCB 66 and Simbi BB15 of Beauveria bassiana and Esalq-1296 of Cordyceps fumosorosea, registered in Brazil for the management of corn leafhopper Dalbulus maidis, with synthetic insecticides used in the management of sucking insects in the initial growth stage of maize crops. The biological index was used to identify the most compatible synthetic insecticides with each fungal isolate tested and isolate IBCB 66 of B. bassiana was the most sensitive. In addition, most mixtures of synthetic insecticides with mycoinsecticides were physically compatible, except for the mixture of mycoinsecticide based on isolate Simbi BB15 of B. bassiana (OD formulation) with insecticides based on acephate, profenophos + cypermethrin, and dinotefuran + lambda-cyhalothrin, which showed absence of homogeneity. Field trials (on-farm assessments) of two-crop seasons indicate that compatibility of insecticides with mycoinsecticides is a key factor for the effectiveness of mixtures in D. maidis population suppression, reduction of incidence and severity of corn stunt complex (CSC), and yield of corn crops. The mixtures of imidacloprid + beta-cyfluthrin and imidacloprid + bifenthrin with mycoinsecticides based on B. bassiana (isolate Simbi BB15) and C. fumosorosea (isolate Esalq-1296) showed the best results in all parameters assessed. Thus, the association of mycoinsecticides with synthetic insecticides is a promising alternative for the management of the corn leafhopper and CSC pathosystem. However, the compatibility of synthetic insecticides is crucial for the success of the associated use of chemical and fungal agents.

Effect of Pesticides and a Long-Life Inoculant on Nodulation Process and Soybean Seed Quality during Storage

Inoculants containing strains of bacteria that fix atmospheric N that are tolerant or resistant to chemical products commonly used in seed treatment are classified as long-life inoculants, which contribute to improving the efficiency of nodulating bacteria in soybean crops. The objective of this work was to evaluate the effects of applying commonly used pesticides in seed treatment and a long-life inoculant, alone or in combination, on the nodulation process and seed quality of soybeans during storage. The first experiment was carried out in a greenhouse using a completely randomized design, in an 8 × 2 factorial arrangement, with three replications. The treatments consisted of applications of industrial seed treatments: control, MaximAdvanced, Fortenza, long-life inoculant, MaximAdvanced + Fortenza, MaximAdvanced + long-life inoculant, Fortenza + long-life inoculant, and MaximAdvanced + Fortenza + long-life inoculant. The seeds were sown in pots containing soils from two crop areas. The second experiment was carried out in a laboratory, using a completely randomized design in an 8 × 7 factorial arrangement, with four replications. The treatments consisted of the same eight treatments used in the greenhouse experiment, which were applied before packaging and storing the seeds for two months. The industrial seed treatment with the mixture of fungicide, insecticide, and inoculants improved the soybean photosynthesis and nodulation processes, regardless of the history of the area. Soybean seeds can be stored for commercial purposes for up to 40 days, regardless of the seed treatment with fungicide, insecticide, and long-life inoculant applied alone or in combination.