Abamectin Concentrations Research Articles

Abamectin at environmentally relevant concentrations impairs bone development in zebrafish larvae

Abamectin (ABM) is a widely used pesticide in agriculture and veterinary medicine, which primarily acts by disrupting the neurological physiology of pests, leading to their paralysis and death. Its extensive application has resulted in contamination of many natural water bodies. While the adverse effects of ABM on the growth and development of non-target organisms are well documented, its impact on bone development remains inadequately studied. The present study aimed to investigate the effects of environmentally relevant concentrations of ABM (1, 5, 25 μg/L) on early bone development in zebrafish. Our results indicated that ABM significantly affected both cartilage and bone development of zebrafish larvae, accompanied by dose-dependent increase in deformity and mortality rates, as well as exacerbated apoptosis. ABM exposure led to deformities in the ceratobranchial (cb) and hyosymplectic (hs), accompanied by significant increases in the length of the palatoquadrate (pq). Furthermore, significant decreases in the CH-CH angle, Meckel's-Meckel's angle, and Meckel's-PQ angle were noted. Even at the safe concentration of 5 μg/L (1/10 of the 96 h LC50), ABM delayed the process of bone mineralization in zebrafish larvae. Real-time fluorescent quantitative PCR results demonstrated that ABM induced differential gene expression associated with cartilage and bone development in zebrafish. Thus, this study provides preliminary insights into the effects and molecular mechanisms underlying ABM's impact on the bone development of zebrafish larvae and offers new evidence for a better understanding of its toxicity.

Abamectin-induced behavioral alterations link to energy metabolism disorder and ferroptosis via oxidative stress in Chinese mitten crab, Eriocheir sinensis

The increasing application of abamectin (ABM) in agriculture has raised concerns regarding its environmental safety and potential adverse effects on aquatic environment safety. In the present study, the toxic effects of ABM exposure on the adult Chinese mitten crab, Eriocheir sinensis were investigated, with a focus on locomotion impairment, behavioral changes, oxidative stress, energy metabolism disruption, and ferroptosis. Crabs were exposed to sublethal concentrations of ABM at 2, 20 and 200 μg/L. After 21 d chronic exposure to 200 μg/L, residual ABM in hepatopancreas and muscles were detected as 12.24 ± 6.67 and 8.75 ± 5.42 μg/Kg, respectively. By using acute exposure experiments (96 h), we observed significant locomotion and behavioral alterations, alongside biochemical evidences of oxidative stress and energy metabolism impairment. The presence of ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, was notably identified in the hepatopancreas. Functional tests with N-acetylcysteine (NAC) supplementation showed restored behavioral responses and decrease of ferroptosis levels. It suggests that mitigating oxidative stress could counteract ABM-induced toxicity. Our findings highlight the critical roles of oxidative stress and ferroptosis in mediating the toxic effects of ABM on E. sinensis, underscoring the need for strategies to mitigate environmental exposure to pesticides.

Effect of abamectin on osmoregulation in red swamp crayfish (Procambarus clarkii).

As a widely used pesticide, abamectin could be a threat to nontarget organisms. In this study, the toxic mechanism of abamectin on osmoregulation in Procambarus clarkii was explored for the first time. The results of this study showed that with increasing abamectin concentration, the membrane structures of gill filaments were damaged, with changes in ATPase activities, transporter contents, biogenic amine contents, and gene expression levels. The results of this study indicated that at 0.2mg/L abamectin, ion diffusion could maintain osmoregulation. At 0.4mg/L abamectin, passive transport was inhibited due to damage to the membrane structures of gill filaments, and active transport needed to be enhanced for osmoregulation. At 0.6mg/L abamectin, the membrane structures of gill filaments were seriously damaged, and the expression level of osmoregulation-related genes decreased, but the organisms were still mobilizing various transporters, ATPases, and biogenic amines to address abamectin stress. This study provided a theoretical basis for further study of the effects of contaminations in aquatic environment on the health of crustaceans.

Combined effects of polyethylene terephthalate and abamectin on enzymatic activity and histopathology response in juvenile zebrafish (Danio rerio).

One of the most pressing global environmental issues is the widespread abundance and distribution of microplastics (MPs). MPs can act as vectors for other contaminants in the environment making these small plastic particles hazardous for ecosystems. The presence of MPs in aquatic environments may pose threats to aquatic organisms that ingest them. This study examined effects of abamectin (ABM) and polyethylene terephthalate (PET) MP fragments on histopathological and enzymatic biomarkers in zebrafish (Danio rerio). Zebrafish were exposed for 96 h to pristine PET-MPs at concentrations of 5 mg/L and 10 mg/L, ABM alone at 0.006 mg/L, and the same concentration of ABM in the presence of PET-MPs in aquaria. Histopathological analysis revealed tissue content changes in liver and kidney in the presence of ABM individually and in combination with MPs. Results of enzymatic analysis showed that MPs increased the bioavailability and toxicity of pesticides due to inhibition of catalase (CAT) and acid phosphatase (ACP) enzymes. However, MPs did not affect the toxicity of ABM for glutathione s-transferase (GST) enzyme. Despite the inhibition of acetylcholinesterase (AChE) in MPs or ABM treatments, and some neurotoxicity, no change in activity of this enzyme and neurotoxicity was observed in the combined MPs and ABM treatments, although toxicity effects of MPs and ABM on zebrafish require more detailed studies.

Functional Analysis of Insecticide Inhibition and Metabolism of Six Glutathione S-Transferases in the Rice Stem Borer, Chilo suppressalis.

The glutathione S-transferases (GSTs) are important detoxifying enzymes in insects. Our previous studies found that the susceptibility of Chilo suppressalis to abamectin was significantly increased when the CsGST activity was inhibited by glutathione (GSH) depletory. In this study, the potential detoxification mechanisms of CsGSTs to abamectin were explored. Six CsGSTs of C. suppressalis were expressed in vitro. Enzymatic kinetic parameters including Km and Vmax of recombinant CsGSTs were determined, and results showed that all of the six CsGSTs were catalytically active and displaying glutathione transferase activity. Insecticide inhibitions revealed that a low concentration of abamectin could effectively inhibit the activities of CsGSTs including CsGSTd1, CsGSTe4, CsGSTo2, CsGSTs3, and CsGSTu1. However, the in vitro metabolism assay found that the six CsGSTs could not metabolize abamectin directly. Additionally, the glutathione transferase activity of CsGSTs in C. suppressalis was significantly increased post-treatment with abamectin. Comprehensive analysis of the results in present and our previous studies demonstrated that CsGSTs play an important role in detoxification of abamectin by catalyzing the conjugation of GSH to abamectin in C. suppressalis, and the high binding affinities of CsGSTd1, CsGSTe4, CsGSTo2, CsGSTs3, and CsGSTu1 with abamectin might also suggest the involvement of CsGSTs in detoxification of abamectin via the noncatalytic passive binding and sequestration instead of direct metabolism. These studies are helpful to better understand the detoxification mechanisms of GSTs in insects.

Uncovering hidden dangers: The combined toxicity of abamectin and lambda-cyhalothrin on honey bees

Studying the toxic effects of pesticides on bees has consistently been a prominent area of interest for researchers. Nonetheless, existing research has predominantly concentrated on individual toxicity assessments, leaving a gap in our understanding of mixed toxicity. This study delves into the individual and combined toxic effects of abamectin (ABA) and lambda-cyhalothrin (LCY) on honey bees (Apis mellifera) in laboratory settings. We discovered that ABA (96 h-LC50 value of 0.079 mg/L) exhibited greater acute toxicity to honey bees compared to LCY (96 h-LC50 value of 9.177 mg/L). Moreover, the mixture of ABA and LCY presented an acute antagonistic effect on honey bees. Additionally, our results indicated that exposure to LCY, at medium concentration, led to a reduction in the abundance of gut core bacterium Snodgrassella. However, an increase in the abundance of Bifidobacterium was noted when exposed to a medium concentration of LCY and its mixture with ABA. Transcriptomic analysis revealed significant regulation of certain genes in the medium concentration of all three treatments compared to the control group, primarily enriching in metabolism and immune-related pathways. Following chronic exposure to field-relevant concentrations of ABA, LCY, and their mixture, there were significant alterations in the activities of immunity-related enzyme polyphenol oxidase (PPO) and detoxification enzymes glutathione S-transferase (GST) and carboxylesterase (CarE). Additionally, the expression of four genes (abaecin, cyp9e2, cyp302a1, and GstD1) associated with immune and detoxification metabolism was significantly altered. These findings suggest a potential health risk posed by the insecticides ABA and LCY to honey bees. Despite exhibiting acute antagonistic effect, mixed exposure still induced damage to bees at all levels. This study advances our knowledge of the potential adverse effects of individual or combined exposure to these two pesticides on non-target pollinators and offers crucial guidance for the use of insecticides in agricultural production.

Effect of abamectin and profenofos insecticide on stingless bee, Tetragonula laeviceps Smith (Hymenoptera: Apidae: Meliponini)

Pollinators such as the bee Tetragonula laeviceps Smith are essential components of ecosystems that provide services to plants. However, the massive use of pesticides in crops can affect the existence of pollinating bees and even cause a decrease in bee populations in the field. This study aimed to determine the effect of abamectin and profenofos insecticides on T. laeviceps. The methods used in the test were bee attractiveness bioassay, toxicity test of dermal application (topical and residual), and oral application with the abamectin and profenofos. The results of the bioassay showed that bees were more attracted to the aroma of the insecticide abamectin 180 ppm than profenofos 1500 ppm. The recommended concentrations of abamectin and profenofos in the field were 180 and 1500 ppm, respectively, so this topical and oral application showed a high level of danger to bees because it can kill >80% of bees. The LD50 values of the insecticides abamectin (0.0064 ppm) and profenofos (0.0345 ppm) were classified as highly toxic based on EPA classification. Therefore, insecticides with active ingredients, particularly abamectin and profenofos, are harmful to T. laeviceps.

Route of exposure to veterinary products in bees: Unraveling pasture's impact on avermectin exposure and tolerance in stingless bees.

Deforestation rapidly increases in tropical regions, primarily driven by converting natural habitats into pastures for extensive cattle ranching. This landscape transformation, coupled with pesticide use, are key drivers of bee population decline. Here, we investigate the impact of pasture-dominated landscapes on colony performance, pesticide exposure, and insecticide sensitivity of the stingless bee Tetragonisca angustula. We monitored 16 colonies located in landscapes with varying proportions of pasture. We collected bee bread for pesticide and palynological analysis. We found a positive correlation between pollen diversity and colony growth, with no effect of the proportion of pasture in the landscape. In contrast, we detected prevalent and hazardous concentrations of the insecticide abamectin (9.6-1,856 µg/kg) in bee bread, which significantly increased with a higher proportion of pasture. Despite the abamectin exposure, the bee colonies displayed no adverse effects on their growth, indicating a potential tolerance response. Further investigations revealed that bees from sites with higher proportions of pasture showed significantly reduced mortality when exposed to a lethal concentration of abamectin (0.021 µg/µL) after 48 h. Since abamectin is scarcely used in the study area, we designed an experiment to track ivermectin, a closely related antiparasitic drug used in cattle. Our findings uncovered a new exposure route of bees to pesticides, wherein ivermectin excreted by cattle is absorbed and biotransformed into abamectin within flowering plants in the pastures. These results highlight that unexplained exposure routes of bees to pesticides remain to be described while also revealing that bees adapt to changing landscapes.

Estimation insecticidal action of Abamectin and Neem oil against Tuta absoluta insect (Lepidoptera : Gelechiidae)

Abstract
 Tuta absoluta insect is one of the pests that has spread recently as a major pest for many species of the nightshade family especially the tomato crop, as it was recorded as an imported pest in Iraq in 2009. The harmful role of this insect is the larvae, as the larvae work mines as a result of their feeding on the mesophyll layer in the crop leaves, which affects the process of photosynthesis, in addition to the holes they make in the stems and fruits, which quickly become infected with mold as a result of the action of pathogens . Based on the above, this experiment was conducted to demonstrate the effectiveness of some biological control elements in management the tomato leaf miner T. absoluta, which may have an important role in reducing its spread. Laboratory biocontrol tests indicated that significant difference among the treatments compared to control for all used pesticides concentrations and all time durations also biocide abamectin was superior to the botaincal insecticide neem oil in mortality rates. Results showed that the relative effectiveness of pesticides increased with the increase in the concentration used for all pesticides, the highest mortality rates were at high concentrations of both pesticides used in the experiment also increased with increasing time period, larvae mortality at a concentration of 10% for neem oil was 68.55, and the larvae mortality at 0.50 concentration of abamectin was 67.50 after 24 hours of treatment, and this percentage began to increase until it reached (90% and 94.50%) for ( neem oil and abamectin) respectively after 72 hours of treatment.

Effects of abamectin on nonspecific immunity, antioxidation, and apoptosis in red swamp crayfish (Procambarus clarkii)

Abamectin, a pesticide of 16-member macrocyclic lactones, is widely applied in agriculture. As an important environmental factor, pesticides pose a great threat to defense system in aquatic animals. Procambarus clarkii is one of the most important economic aquatic animals in China. It is necessary to explore the defense mechanism of P. clarkii to abamectin. In this study, P. clarkii were exposed to 0, 0.2, 0.4, 0.6 mg/L abamectin, immune- and antioxidant-related enzymes activities, genes expression levels, and histological observations were used to analyze the defense capacity of P. clarkii to abamectin. With increasing abamectin concentration, reactive oxygen species (ROS) level and malondiadehyde (MDA) content increased significantly. Meanwhiile, acid phosphate (ACP), alkaline phosphatase (AKP) activities, total haemocyte counts (THC), and Crustin expression level decreased significantly, superoxide dismutase (SOD), catalase (CAT) activities, total antioxidant capacity (T-AOC), and GPX expression level also decreased significantly. Hematoxylin & eosin (H&E) observation showed that with increasing abamectin concentration, hepatopancreas were damaged, especially membrane structure. Through TUNEL observation and apoptosis-related genes (PcCTSL, Bcl-2, Bax, BI-1, PcCytc, caspase-3) expression levels, with increasing abamectin concentration, apoptosis rate increased significantly. Results of this study indicated that abamectin caused oxidative damage to P. clarkii, resulting in damage to defense system, suppression of nonspecific immunity and antioxidation, and promotion of apoptosis. It provided theoretical basis for healthy P. clarkii culture, and for further study on defense mechanism of aquatic animals to pesticides.

The toxic effects of some acaricides on the tomato russet mite and its predator Amblyseius swirskii Athias-Henriot, 1962 (Acari: Phytoseiidae)

The tomato russet mite, Aculops lycopersici (Massee, 1937) (Acari: Eriophyidae) is a common pest of tomatoes. The predatory mite, Amblyseius swirskii Athias-Henriot, 1962 (Acari: Phytoseiidae), can control A. lycopersici populations. To integrate biological and chemical control of A. lycopersici, side effects of the lethal concentrations of acaricides, as a predator, on A. swirskii should be considered. The lethal concentrations of 14 acaricides for A. lycopersici were determined under laboratory conditions at Bursa Uludağ University during 2017-2018. To understand the toxic impacts of the acaricides on juveniles and females of A. swirskii, the LC99 values for A. lycopersici of each acaricide were applied to A. swirskii. The reproduction reduction effects of the LC99 values were also assessed. Quite low concentrations of abamectin, milbemectin, pyridaben, azadirachtin and sulphur were found to be toxic for A. lycopersici. Based on the side effect scale, the LC99 values of abamectin, acequinocyl, bifenazate, fenproximate, fenbutatin oxide, hexythiazox, milbemectin and sulphur that killed A. lycopersici were found to be slightly toxic to both females and juveniles of A. swirskii. The results of this comparative toxicological study have showed that more field studies should be conducted to evaluate the effectiveness of using low concentrations of acaricides with A. swirskii in combination for controlling A. lycopersici.

Studying the Efficiency of Essential Oil Blends with the Pesticide Abamectin against Adult and Larvae of Trogoderma granarium (Everts)

Al Mansoori, D.H.H., F.S. Al Bayati and S.M. Jawad. 2023. Studying the Efficiency of Essential Oil Blends with the Pesticide Abamectin against Adult and Larvae of Trogoderma granarium (Everts). Arab Journal of Plant Protection, 41(1): 18-27. https://doi.org/10.22268/AJPP-41.1.018027 Using chemical pesticides has several adverse effects on the environment and human health. Therefore, natural plant extract products may provide an alternative to chemical pesticides for the control of stored pests and reduce the impact caused by chemical pesticides. The use of aromatic essential oils in the management of insect pests has recently gained popularity due to their chemical composition and the presence of many important compounds for controlling harmful insects, such as stored grain pests. A series of laboratory studies were conducted to determine the lowest dosage of the insecticide Abamectin combined as (1:1) with Eucalyptus oil against the insect's adult, third, and fifth stage larvae khapra. In addition, the repellency or attraction of Eucalyptus oil has been examined. The findings indicated that various concentrations of Abamectin were used against the khapra beetle; the death rates of the concentrations (0.6 and 0.15 ml/L) were 91.67 and 78.33% compared to the control. The concentration 0.3 and 0.15 mg/L when mixed with Eucalyptus oil (1:1) gave 98.33 and 86.67% mortality, respectively, compared to the control, which was 0.00%. The result also indicated that mortality rates were highest by the concentration of 0.6 ml/L with a death rate of 85.55 and 80.00% of the third and fifth instar larvae, while the concentration of 0.15 ml/L gave death rates of 74.44 and 67.77%, respectively. the addition of Eucalyptus oil at a ratio of 1:1 to the insecticide concentrations 0.3 ml/L led to an increase in the mortality rates of the third and fifth instar larvae that reached 88.89 and 85.55%, respectively. Likewise, the death rates of using the insecticide concentration of 0.15 ml/L were 81.11 and 82.22%, respectively. The study also indicated the effect of Eucalyptus oil alone on the percentage of death of adults, the third and fifth instars of the Khapra beetle were 83.33, 48.61 and 65.55%, respectively, whereas the death rate for the control treatment was 1.67%. The study also confirmed that Eucalyptus oil had an 83.00% repellant effect on adults, whereas it had an 84.50% attraction effect on fifth-stage larvae. The study suggests using these essential oils as a potential safe alternative to insecticides. Keywords: Khapra Beetle, Eucalyptus oil, pesticides, Essential oils

Single and mixed exposure to distinct groups of pesticides suggests endocrine disrupting properties of imidacloprid in zebrafish embryos

Due to their selective toxicity to insects, nicotinoid compounds have been widely used to control pests in crops and livestock around the world. However, despite the advantages presented, much has been discussed about their harmful effects on exposed organisms, either directly or indirectly, with regards to endocrine disruption. This study aimed to evaluate the lethal and sublethal effects of imidacloprid (IMD) and abamectin (ABA) formulations, separately and combined, on zebrafish (Danio rerio) embryos at different developmental stages. For this, Fish Embryo Toxicity (FET) tests were carried out, exposing two hours post-fertilization (hpf) zebrafish to 96 hours of treatments with five different concentrations of abamectin (0.5–11.7 mg L−1), imidacloprid (0.0001–1.0 mg L−1), and imidacloprid/abamectin mixtures (LC50/2 − LC50/1000). The results showed that IMD and ABA caused toxic effects in zebrafish embryos. Significant effects were observed regarding egg coagulation, pericardial edema, and lack of larvae hatching. However, unlike ABA, the IMD dose-response curve for mortality had a bell curve display, where medium doses caused more mortality than higher and lower doses. These data demonstrate the toxic influence of sublethal IMD and ABA concentrations on zebrafish, suggesting that these compounds should be listed for river and reservoir water-quality monitoring.

Control effects and sublethal effects of four pesticides on Atheloca bondari (Lepidoptera: Pyralidae) caterpillars

• The concentration of abamectin used to control A. guerreronis caused 100% mortality of A. bondari caterpillars; • The residues of abamectin, azadirachtin, and fenpyroximate affected the behaviour of A. bondari caterpillars; • Acaricide residues did not interfere with infestation of coconut fruits by A. bondari caterpillars. Atheloca bondari Heinrich is an opportunistic lepidopteran that uses necrosis caused by the mite Aceria guerreronis Keifer, the most important pest of the coconut palm, to access the meristematic region of coconuts. Because of this moth-mite positive association, pesticides used to control A. guerreronis (abamectin, azadirachtin, fenpyroximate, and pyridaben) may impact A. bondari caterpillar behavior and/or survival. Thus, we used three methodologies (toothpick, triangle, and mesocarp fragment) to evaluate mortality caused by abamectin, the most commonly used pesticide to control A. guerreronis . The toothpick method proved to be suitable for toxicity tests of A. bondari caterpillars. Subsequently, the mortality caused by these four pesticides was evaluated, and abamectin caused 100% mortality in A. bondari caterpillars. Abamectin showed higher toxicity than the other pesticides to A. bondari caterpillars, with LC 50 and LC 95 values of 1.35 and 3.64 mg/L, respectively. The preference test showed that A. bondari caterpillars infested pesticide-treated fruits in the same proportion as untreated fruits. In the behavioral test, A. bondari caterpillars showed lower locomotor speed when exposed to surfaces with abamectin, azadirachtin, and fenpyroximate residues. Our study presented that pesticides used to control A. guerreronis affect the behavior and survival of A. bondari caterpillars. We discuss how spraying these pesticides can indirectly control the population of A. bondari , reducing the impact of this moth on coconut production, and modifying the importance of this species as a pest of coconut palm.

Toxicity and Enzymatic Activity of Reduced Doses of Insecticides in Chrysoperla carnea 1 and Bactericera cockerelli 2

The objective of this research was to compare the toxicity of reduced doses and enzymatic activity associated with insecticide tolerance to abamectin and profenofos on Chrysoperla carnea Stephens and its prey Bactericera cockerelli Sulc. Residual toxicity was measured at 0.1, 0.5, and 1.0% of the recommended dose of abamectin and profenofos for controlling B. cockerelli. Measured were α-esterases, β-esterases, glutathione S-transferases (GSTs), and oxidase content of larvae and nymphs of C. carnea and B. cockerelli exposed to the insecticides. The three abamectin concentrations killed more nymphs of the pest than did larvae of green lacewing. Profenofos at 1.0% concentration was very toxic to the pest and its predator. At concentrations of 0.5 and 1.0, fewer died and was similar for both species. Abamectin killed fewer C. carnea than did profenofos at the three doses. Enzymatic activity of α and β-esterase was greater for C. carnea compared with B. cockerelli exposed to abamectin and profenofos. Activity of the enzyme glutathione S-transferases (GSTs) and oxidase content where greater for B. cockerelli than C. carnea. The study demonstrated that abamectin was less toxic to C. carnea and more to B. cockerelli, suggesting the insecticide was very selective, which could be related to greater esterase enzymatic activity.

Synergism of macrocyclic lactones against Haemonchus contortus.

A possible synergistic effect of macrocyclic lactones' (MLs) combination has been previously described against resistant gastrointestinal nematodes of cattle. In addition to synergism, drug-drug interactions between MLs can also result in additive or antagonistic effect, considering the different MLs pharmacokinetics, pharmacodynamics, and interactions with molecular mechanisms of resistance. Therefore, the aim of the current work was evaluated the effect of different MLs combinations against Haemonchus contortus. Infecting larvae of two isolates (one susceptible and one resistant to ivermectin) were used in the larval migration inhibition test. After estimating the half maximal effective concentration of abamectin (ABA), eprinomectin, (EPR), ivermectin (IVM), and moxidectin (MOX) for both isolates, combinations were delineated by a simplex-centroid mixture experiment, and the mixture regression analysis was applied to the special cubic model. A synergistic effect was found for the EPR + MOX against the susceptible isolate as well as the EPR + MOX, IVM + MOX, and ABA + EPR + IVM against the resistant isolate. An antagonistic effect of ABA + IVM + MOX was found against the susceptible isolate. For the susceptible isolate, a higher inhibition was found with greater proportions of EPR and lower proportions of the other drugs compared to the reference mixture. For the resistant isolate, inhibition greater than that of the reference mixture was found with higher proportions of IVM as well as lower proportions of the other drugs. The synergistic and antagonistic effects were dependent on the following: (a) parasite drug resistance profile, (b) the composition of the combination, and (c) the proportions used, with EPR and IVM exerting a greater impact on these effects.

Exposure to lambda-cyhalothrin and abamectin drives sublethal and transgenerational effects on the development and reproduction of Cydia pomonella

The codling moth Cydia pomonella (Lepidoptera: Tortricidae) is a major invasive pest of pome fruits and walnuts worldwide. Lambda-cyhalothrin (LCT) and abamectin (AM) have been frequently used in C. pomonella control, but control of this pest is very difficult because shortly after hatching, larvae of this insect bore tunnels and hide inside host plant fruit. In this study, a simulated field spray bioassay method was developed against neonate larvae of C. pomonella and concentration-response bioassays were conducted to evaluate the susceptibility of the neonate larvae to LCT and AM. Exposure of neonate larvae to sublethal concentration (LC30) of LCT or AM significantly reduced the survival rate of larvae (4th and 5th instars), lowered the mean weight of larvae and pupae, and decreased the daily maximal number of eggs laid and the total number of eggs laid (fecundity) per female. The sublethal effects, including reduced body mass, mean fecundity and net reproductive rate, extended mean generation time, and shortened oviposition period, were also found in transgenerational offspring. Furthermore, the transgenerational maternal effects were more obvious for AM than LCT, in comparison to the control. Additionally, the estimated population size was decreased by exposure to LC30 of LCT and AM, and the observed reduction of fecundity and population size within and across generations was likely the result of the downregulation of the reproduction-related vitellogenin gene (CpVg) after exposure to LC30 of LCT and AM. These results provide a better understanding of the overall effects of LCT and AM on C. pomonella and the transgenerational effects which should be taken into consideration when using insecticides in order to control C. pomonella.

Abamectin causes cardiac dysfunction in carp via inhibiting redox equilibrium and resulting in immune inflammatory response and programmed cell death.

This study aims to investigate the effects of environmentally relevant concentrations of abamectin on the cardiac function of carp and the potential mechanisms. Here, male carp were exposed to abamectin, and cardiac function-related enzymatic markers were examined. Cardiac histopathology, redox equilibrium, inflammation, and cell death were evaluated. Abamectin exposure caused cardiac dysfunction by upregulating lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatine kinase (CK), creatine Kinase MB isoenzyme (CK-MB) and white blood cells (WBCs), and decreasing red blood cells (RBCs) and hemoglobin (Hb). DHE staining and biochemical assays revealed that abamectin caused ROS release and oxidative stress by inhibiting Nrf2-ARE pathway. Histopathological and real-time fluorescence quantitative PCR (RT-qPCR) assays revealed that abamectin caused myocardial fiber swelling and inflammatory cell infiltration, enhanced pro-inflammatory cytokines tumor necrosis factor-α (Tnf-α), interleukin-1 beta (Il-1β), and Il-6 levels and attenuated anti-inflammatory cytokines Il-10 and transforming growth factor beta 1 (Tgf-β1) through activating NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome and nuclear factor kappa-B (NF-κB) pathway. Tunel staining showed that abamectin triggered cardiac apoptosis via activating p53-mediated mitochondrial apoptosis with elevated bcl2-associated X (Bax), reduced B-cell lymphoma-2 (Bcl-2), and activated Caspase-9 and Caspase-3. Immunoblot analysis revealed that abamectin activated autophagic flow by inhibiting mammalian target of rapamycin (mTOR), resulting in the conversion of LC3B from LC3-I to LC3-II, elevation of autophagy protein 5 (Atg5), and reduction of p62. Overall, abamectin caused cardiac dysfunction in carp via inhibiting redox equilibrium and resulting in immune inflammatory response and programmed cell death.

Abamectin promotes behavior changes and liver injury in zebrafish.

The indiscriminate use of pesticides is a worldwide concern due to the environment contamination since it can cause deleterious effects to non-target organisms including the fishes. The effects of abamectin, a pesticide from the avermectin family, were evaluated in adult zebrafish (Danio rerio) after exposure to a commercial formula commonly used in Brazil. The animals were submitted to acute (96 h) and to a short-term chronic exposure (15 days) of distinct concentrations of abamectin. LC50 was determined and a histological study followed by an immunohistochemistry analysis for P-gp and HSP70 identification were performed on livers of the animals submitted to the acute and chronic treatment, respectively. Moreover, behavior patterns were observed daily in both trials. A LC50 value of 105.68 μg/L was determined. The histological analysis revealed a morphological alteration of the hepatocytes, glycogen accumulation, degeneration, and disorganization of the cytoplasm, and a pyknotic, irregular, and laterally located nuclei. The immunohistochemistry for HSP70 and P-gp showed strong staining in the hepatocytes of the control groups and progressive decrease as the concentration of abamectin increased. Changes were observed in body posture, movement around the aquarium, opercular activity, body color and search for food in the groups treated with abamectin. The results presented suggest that abamectin can affect the behavioral pattern of the animals, promote morphological changes, and decrease the expression of HSP70 and P-gp in zebrafish liver.

EFFECT OF NANO-ABAMECTIN IN COMBATING THE TWO-SPOTTED SPIDER MITE TETRANYCHUS URTICAE KOCH (ACARI: TETRANYCHIDAE) UNDER LABORATORY CONDITIONS

The lethal dose for 50% of the mite community was for abamectin and nanoparticles 100 and 24.5 respectively. As for the concentrations of abamectin used, it was from 20 to 1000 mg/liter, and the death rate was from 11 to 85%. While the concentrations used for nanoparticles was from 10 to 250 mg/L, and the mortality from 13 to 96%. Toxicity index value of nano-abamectin was 25 times compared to the traditional abamectin pesticide. The lethal dose for 50% of the mite community was for abamectin and nanoparticles 812.8 and 228.6 mg/L, respectively. The concentrations of abamectin used was from 40 to 1000 mg/liter, and the death rate from 00.63 to 46.63 %. While the used concentrations for nanoparticles was from 10 to 250 mg/L, and the mortality from 5.00 to 67.7 %. Depending on the toxicity index of the pesticide, the nano-abamectin solution was the most toxic to the egg stage of the mite, where the toxicity index value of nano-abamectin particles was 28 times compared to the traditional abamectin pesticide used