Different Concentrations Of Imidacloprid Research Articles

Comparing the effects of three neonicotinoids on embryogenesis of the South African clawed frog Xenopus laevis

Neonicotinoids (NEOs) are widely used insecticides that are ubiquitous in agricultural use. Since NEOs are found in natural waters as well as in tap water and human urine in regions where NEOs are widely used, NEOs pose a potential hazard to non-target organisms such as animals and humans. Some of the commonly detected NEOs are imidacloprid (IMD), thiamethoxam (TMX), and its metabolite clothianidin (CLO). Although previously published scientific information, including an assessment of the environmental risks, particularly for bees, had resulted in a ban on the outdoor use of these three NEOs in the EU – their use is now only permitted in closed greenhouses – these NEOs continue to be used in agriculture in many other parts of the world. Therefore, a detailed study and comparison of the effects of NEOs on the embryonic development of non-target organisms is needed to further define the risk profiles.Embryos of the South African clawed frog Xenopus laevis, a well-established aquatic model, were exposed to different concentrations of IMD, TMX, or CLO (0.1–100 mg/L) to study and compare the possible effects of a single contaminant in natural water bodies on early embryogenesis. The results included a reduced body length, a smaller orbital space, impaired cranial cartilage and nerves, and an altered heart structure and function. At the molecular level, NEO exposure partially resulted in an altered expression of tissue-specific factors, which are involved in eye, cranial placode, and heart development.Our results suggest that the NEOs studied negatively affect the embryonic development of the non-target organism X. laevis. Since pesticides, especially NEOs, pollute the environment worldwide, it is suggested that they are strictly controlled and monitored in the areas where they are used. In addition, the question arises as to whether pesticide metabolites also pose a risk to the environment and need to be investigated further so that they can be taken into account when registering ingredients.

Determination of biochemical and histopathological changes on testicular and epididymis tissues induced by exposure to insecticide Imidacloprid during postnatal development in rats

BackgroundImidacloprid is a neonicotinoid insecticide belonging to the chloronicotinyl nitroguanidine chemical family. Toxicity of IMD for mammals in scientific studies has shown high mutagenic, immunotoxic, teratogenic and neurotoxic effects. The present study was designed to assess the toxic effects of imidacloprid (IMD) on the testicular and epididymis tissues as well as testosterone levels of neonatal male rats.MethodsNeonatal male rats from postnatal day (PND) 1 to PND 26 were consecutively administered with different concentrations of IMD (1, 5 and 10 mg/kg) subcutaneously. The effect of IMD on body and organ weight, lipid profile, histopathological alterations, oxidative stress and altered testosterone levels were assessed in the testis and plasma.ResultsThe results of body weight gain showed a significant difference in group 4 (10 mg/kg) animals as compared to the control. A significant increase in total cholesterol and triglycerides, while a decrease in high-density lipoprotein concentrations was evident. Similarly, a significant decrease in concentrations of antioxidant enzymes (CAT and SOD) among all the IMD-treated groups was evident, when compared to the control. Increased production of ROS was also noticed in the highest-dose treatment group. Further, we observed that IMD-treated rats indicated histopathological changes in the testis and epididymis along with a significant decrease in the plasma testosterone concentrations among IMI-treated groups in contrast to the control. Histological examination of the testis of IMD-treated neonatal male rats also showed decreased spermatogenesis in the treated groups when compared to the control. Furthermore, an increase in lumen diameter and a decrease in epithelial height of seminiferous tubules were also observed in IMD-treated rats in comparison with the control.ConclusionIt is concluded that sub-chronic exposure to IMD in neonatal male rats may induce histopathological changes in reproductive tissues and damage normal testicular functions via inducing oxidative stress, decrease in body weight, disturbing normal blood lipid profile and testosterone concentration. IMD exposure can induce pathophysiological effects calls for further evaluation of this widely used insecticide.

Self-healing demonstration in imidacloprid toxicity with multibiomarkers and biologic pathways

Imidacloprid (IMI) pesticide has significant environmental and ecotoxicological pollution effects. Also, its high potential to enter the aquatic environment reveals the importance of early evaluation of the toxic effects of this compound. This study aimed to evaluate organ responses that can be associated with outcomes at higher levels of biological organization in fish. In this respect, the toxicity mechanism and recovery response process of IMI in rainbow trout (Oncorhyncus mykiss)’ s different tissues (blood, brain, gill and liver) were analyzed with important biomarkers [(hematological indices (RBC, WBC, Hg, Hct, MCV, MCH, MCHC), antioxidant enzyme activities (SOD, CAT, GPx, GSH), MDA, DNA damage (8-OHdG), apoptosis (caspase 3), AChE, TNF α, interleukin 6, Nrf-2, NF-kB activities, histopathological and immunofluorescence analyses (NeuN, BDNF, JNK and Nop10]. Exposure to different concentrations of IMI caused a decrease in RBC, WBC, Hg and Hct levels in O. mykiss. The effect of the same application on brain, gill and liver tissues was determined as inhibitions in antioxidant enzyme activities (SOD, CAT and GPx) and GSH level, inductions on MDA level, DNA damage, caspase-3, TNF α, IL- 6, Nrf-2 and NF-kB activities. As a result of three tissues’ histopathological examination; the degeneration, necrosis and hyperemia in the brain and liver, adhesion, desquamation and inflammation in the lamellar epitheliums has been determined in company with stress-induced responses inducing DNA damage. In the reflection of this situation on histomap results, increases were recorded in BDNF and NeuN levels. In the recovery response, tissue damage profile and detoxification process were differentiated according to dose and marker, and it manifested itself with moderate and mild symptoms. These findings revealed that IMI-mediated oxidative stress was effective in the Nrf-2/GSH/NF-kB pathways, showing strong hemato/hepato, and neurotoxic effects. It has become clear that the severity of the effects caused by IMI exposure is felt more in the brain and liver tissues, and that such contaminants should be taken into account in the risk assessment. During the post-exposure recovery period (after 15 days), AChE activity increased by 21% at high-dose administration. The recovery period was effective in regulating the oxidant/antioxidant balance of the organism by exhibiting serious induction/inhibition in each tissue and biomarker performance.

Assessment of Larval Health and Metamorphosis of the Giant Freshwater Prawn Macrobrachium rosenbergii Larvae during Acute Exposure to Imidacloprid

An acute toxicity study of imidacloprid on the larval health and metamorphosis of the giant freshwater prawn Macrobrachium rosenbergii larvae were carried out during the months of January–August 2021 at the aquatic animal raring and experimenting facility in the Cochin University of Science and Technology, Kerala, India. Imidacloprid is a broad-spectrum neonicotinoid insecticide used against sucking pests infecting agricultural crops as both contact poison and stomach poison. The present study investigated the adverse effects of imidacloprid on the survival rate, feeding behaviour, larval quality and incidence of metamorphosis in Macrobrachium rosenbergii larvae. The 48 h median lethal concentrations (LC50 values) and safe concentration of imidacloprid determined for different larval stages (Zoea I–XI) of M. rosenbergii ranged between 0.000635–0.001388 mg l-1 and 0.000055–0.000191 mg l-1, respectively. Larvae exposed to imidacloprid for 48 h showed decrease in survival rate with increase in concentration of imidacloprid. The results of larval condition index (LCI) that indicates the larval quality showed that imidacloprid reduced the larval health significantly (p<0.05) at high concentrations and is potent to delay the incidence of metamorphosis. The feeding rate of larvae exposed to different concentrations of imidacloprid were found to be significantly (p<0.05) reduced due to paralytic effect of imidacloprid. The present work provides relevant data beneficial for the risk assessment of imidacloprid in M. rosenbergii.

Concentration Dependent Feeding on Imidacloprid by Behaviorally Resistant House Flies, Musca domestica L. (Diptera: Muscidae).

The house fly (Musca domestica L.) is a cosmopolitan and synanthropic pest fly commonly associated with confined animal facilities, known to mechanically vector numerous disease-causing pathogens. Control of adult house flies often relies on insecticides formulated into insecticidal baits, though many baits have failed due to insecticide resistance. House fly resistance to imidacloprid, the most widely used neonicotinoid insecticide available for fly control, has evolved through physiological and behavioral mechanisms in field populations. Behavioral resistance to imidacloprid was documented in field populations of flies from southern California dairies. Lab colonies of these flies were established and behavioral resistance to imidacloprid was selected over several generations. The current study examined the ability of these lab-selected flies to feed on varying concentrations of imidacloprid formulated in sucrose, and if these flies would demonstrate a feeding preference for different concentrations of imidacloprid when exposed in bioassays. Behaviorally resistant flies preferred to feed on untreated sucrose as opposed to treated sucrose at concentrations greater than 25 µg/g imidacloprid when provided sucrose treated with and without imidacloprid. When provisioned with only sucrose treated with a low and high imidacloprid concentration, flies fed on the low concentrations (≤100 µg/g) imidacloprid but reduced feeding on either treatment when concentrations were >100 µg/g imidacloprid. The current study extends the body of knowledge on house fly behavioral resistance to imidacloprid, which could provide insights into future failures of granular fly baits.

Toxicity and genotoxicity of imidacloprid in the tadpoles of Leptodactylus luctator and Physalaemus cuvieri (Anura: Leptodactylidae)

Imidacloprid is a neonicotinoid insecticide used to control agricultural pests around the world. This pesticide can have adverse effects on non-target organisms, especially in aquatic environments. The present study evaluated the toxicity of an imidacloprid-based insecticide in amphibians, using Leptodactylus luctator and Physalaemus cuvieri tadpoles as study models. Spawning of both species were collected within less than 24 h of oviposition from a non-agricultural land at Erechim, Rio Grande do Sul state, Brazil. Survival, swimming activity, body size, morphological malformations, and genotoxic parameters were analyzed at laboratory conditions. A short-term assay was conducted over 168 h (7 days) with five different concentrations of imidacloprid (3–300 µg L−1) being tested. The insecticide did not affect survival, although the tadpoles of both species presented reduced body size, malformed oral and intestine structures, and micronuclei and other erythrocyte nuclear abnormalities following exposure to this imidacloprid-based compound. Exposure also affected swimming activity in L. luctator, which reflected the greater sensitivity of L. luctator to imidacloprid in comparison with P. cuvieri. The swimming activity, body size, and malformations observed in L. luctator and the morphological malformations found in P. cuvieri indicated that even the lowest tested concentration of the insecticide were harmful to amphibians. At concentrations of over 3 μg L−1, P. cuvieri presents a smaller body size, and both species are affected by genotoxic cell damage. This demonstrates that imidacloprid is potentially toxic for the two study species at environmentally relevant concentrations.

Combined Effects of Potassium Perchlorate and a Neonicotinoid on Zebrafish Larvae (Danio rerio).

Imidacloprid (IMI) is part of the neonicotinoids family, insecticides widely used by humans and also found in wastewater. This class of compounds, if present in the environment, can cause toxicity to different species such as bees and gammarids, although little is known about vertebrates such as fish. In addition, several substances have been reported in the environment that can cause damage to aquatic species, such as potassium perchlorate (KClO4), if exposed to high concentrations or for long periods. Often, the co-presence of different contaminants can cause a synergistic action in terms of toxicity to fish. In the present study, we first analyzed different concentrations of IMI (75, 100 and 150 mg/L) and KClO4 (1, 1.5 and 5 mM) to highlight the morphological effects at 96 hpf and, subsequently, chose two nontoxic concentrations to evaluate their co-exposure and the pathway involved in their co-toxicity. Morphological alteration, mucus production, messenger RNA (mRNA) expression related to intestinal function and oxidative stress were measured. These results suggest that co-exposure to IMI and KClO4 could affect zebrafish embryo development by increasing gut toxicity and the alteration of antioxidative defense mechanisms.

Effects of the Neonicotinoid Imidacloprid on the Feeding Behavior of Melipona quadrifasciata anthidioides Lep.

Even though meliponines are among the greatest pollinating agents in Neotropical ecosystems, the populations of these bees are in decline due to anthropic actions, such as the indiscriminate use of pesticides. Neonicotinoids, such as Imidacloprid, are used in many crops and have been shown to be one of the pesticides groups with the most damaging effects on the health of bee colonies. The goals of this work were (1) to evaluate the ability of Melipona quadrifasciata, a native Brazilian stingless bee species, to detect the presence of Imidacloprid in artificial diets, and (2) to evaluate how this insecticide may affect their behavior. For this purpose, behavioral experiments were carried out in observation arenas where artificial flowers containing different concentrations of Imidacloprid (0%, 1%, 5%, 10%, and 20%) were made available to forager bees and their choice and behavior were registered. Our results showed that bee choices were not affected by the different concentrations of Imidacloprid, even at extremely high doses in the flowers (20%). It was also found that the presence of this insecticide interfered with the communication between individuals as a result of reduced antennation events. Both findings, the apparent inability of bees to detect the presence of the insecticide and the change in behavior caused by the exposition to the volatilized product, may rapidly lead to colony losses in nature.

In vitro effects of imidacloprid on honey bee sperm: evaluation using computer-aided sperm analysis (CASA)

Pesticides are considered as the most important factors of pollinators’ decline. Imidacloprid (IMD), belonging to Neonicotinoids class, is widely used as a powerful insecticide but generating important negative effects on honey bees. The current study investigated the direct effect of IMD on bee spermatozoa. The experimental design consisted of in vitro co-incubation of bee gametes with three different concentrations of IMD 1, 10, and 25 μM for 15 min. Conventional microscopic and Computer-aided sperm analyses (CASA) were concomitantly used with a dual goal: to evaluate objectively the effects of IMD on sperm parameters on the one hand and to report computer kinematic parameters in the control group, without IMD treatment, on the other hand. The results revealed apparent negative effects in a dose-dependent manner with motility collapsing completely at 25 μM of IMD. The current results highlighted the direct impact of IMD on bee spermatozoa and revealing the potential subsequent effects on bee reproduction. This study reported also drone computer sperm parameters that could serve as a reference in the studied region. Bee sperm velocities showed the lowest values ever reported in the different animal species. The CASA system appeared as objective and a sensitive method to detect subtle toxic effects on bee sperm, and this opens real perspectives particularly in studying existing correlations between CASA parameters and fertility outputs of different environmentally toxic molecules.

Determination of imidacloprid in beehive samples by UHPLC-MS/MS

Imidacloprid is a systemic insecticide belonging to the neonicotinoid family. It was the first neonicotinoid introduced in the mid-1990s, and since then, its use has grown rapidly to control pests in a variety of agricultural crops. Several studies have shown that neonicotinoids translocate to the nectar and pollen of treated plants, which represents a potential risk to pollinators. Therefore, an open-field feeding study was carried out. For this purpose, 30 beehives of Apis mellifera L. were installed in the same apiary. All colonies were in similar health and population conditions when assays were started. For seven weeks, colonies were fed with sucrose syrup with different concentrations of imidacloprid: 15, 30, 120 and 240 μg kg−1. Thus, the assays were divided into four treatments and a witness (Control) with no added imidacloprid. To check the hives' exposure to imidacloprid and evaluate its distribution, sampling of adult worker bees and larvae was performed before, during and after the whole feeding period (7 weeks). Furthermore, in the 15th week, honey and beeswax (honeycomb) samples were collected from the brood chamber and honey super of all hives. Analytical methodologies for sample preparation based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) procedure were optimized and validated. After soaking the bees and honey samples and the extraction using acetonitrile with MgSO4 and NaCl salts, a dispersive solid-phase extraction (d-SPE) step with MgSO4, PSA and C18 was applied. Melted beeswax was subjected to an acetonitrile extraction, followed by freeze-out and d-SPE with PSA and C18. Extracts were evaluated in a UHPLC-MS/MS system. LOQ (μg kg−1) values were 0.25, 0.50 and 1 for honey, bees and beeswax, respectively. Satisfactory recovery performance was achieved with relative standard deviation ≤20%. Residue concentrations of imidacloprid in samples showed correlation with the doses supplied, indicating exposure of the beehives to the insecticide. Honey stored approximately 60% of the loaded imidacloprid through syrup feeding.

Stress indicator gene expression profiles, colony dynamics and tissue development of honey bees exposed to sub-lethal doses of imidacloprid in laboratory and field experiments.

In this study, different context-dependent effects of imidacloprid exposure on the honey bee response were studied. Honey bees were exposed to different concentrations of imidacloprid during a time period of 40 days. Next to these variables, a laboratory-field comparison was conducted. The influence of the chronic exposure on gene expression levels was determined using an in-house developed microarray targeting different immunity-related and detoxification genes to determine stress-related gene expression changes. Increased levels of the detoxification genes encoding, CYP9Q3 and CYT P450, were detected in imidacloprid-exposed honey bees. The different context-dependent effects of imidacloprid exposure on honey bees were confirmed physiologically by decreased hypopharyngeal gland sizes. Honey bees exposed to imidacloprid in laboratory cages showed a general immunosuppression and no detoxification mechanisms were triggered significantly, while honey bees in-field showed a resilient response with an immune stimulation at later time points. However, the treated colonies had a brood and population decline tendency after the first brood cycle in the field. In conclusion, this study highlighted the different context-dependent effects of imidacloprid exposure on the honey bee response. These findings warn for possible pitfalls concerning the generalization of results based on specific experiments with short exposure times. The increased levels of CYT P450 and CYP9Q3 combined with an immune response reaction can be used as markers for bees which are exposed to pesticides in the field.

Effects of imidacloprid on detoxifying enzyme glutathione S-transferase on Folsomia candida (Collembola).

Chemical analyses of the environment can document contamination by various xenobiotics, but it is also important to understand the effect of pollutants on living organisms. Thus, in the present work, we investigated the effect of the pesticide imidacloprid on the detoxifying enzyme glutathione S-transferase (GST) from Folsomia candida (Collembola), a standard test organism for estimating the effects of pesticides and environmental pollutants on non-target soil arthropods. Test animals were treated with different concentrations of imidacloprid for 48h. Changes in steady-state levels of GST messenger RNA (mRNA) and GST enzyme activity were investigated. Extracted proteins were separated according to their sizes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the resolved protein bands were detected by silver staining. The size of the glutathione (GSH) pool in Collembola was also determined. A predicted protein sequence of putative GSTs was identified with animals from control group. A 3-fold up-regulation of GST steady-state mRNA levels was detected in the samples treated with 5.0mgL-1 imidacloprid compared to the control, while a 2.5- and 2.0- fold up-regulation was found in organisms treated with 2.5 and 7.5mgL-1 imidacloprid, respectively. GST activity increased with increasing imidacloprid amounts from an initial activity of 0.11μmolmin-1mg-1 protein in the control group up to 0.25μmolmin-1mg-1 protein in the sample treated with the 5.0mgL-1 of pesticide. By contrast, the total amount of GSH decreased with increasing imidacloprid concentration. The results suggest that the alteration of GST activity, steady-state level of GST mRNA, and GSH level may be involved in the response of F. candida to the exposure of imidacloprid and can be used as biomarkers to monitor the toxic effects of imidacloprid and other environmental pollutants on Collembola.

Imidacloprid impairs the post-embryonic development of the midgut in the yellow fever mosquito Stegomyia aegypti (=Aedes aegypti).

The mosquito Stegomyia aegypti (=Aedes aegypti) (Diptera: Culicidae) is a vector for the dengue and yellow fever viruses. As blood digestion occurs in the midgut, this organ constitutes the route of entry of many pathogens. The effects of the insecticide imidacloprid on the survival of St. aegypti were investigated and the sub-lethal effects of the insecticide on midgut development were determined. Third instar larvae were exposed to different concentrations of imidacloprid (0.15, 1.5, 3.0, 6.0 and 15.0 p.p.m.) and survival was monitored every 24 h for 10 days. Midguts from imidacloprid-treated insects at different stages of development were dissected and processed for analyses by transmission electron microscopy, immunofluorescence microscopy and terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) assays. Imidacloprid concentrations of 3.0 and 15.0 p.p.m. were found to affect midgut development similarly. Digestive cells of the fourth instar larvae (L4) midgut exposed to imidacloprid had more multilamellar bodies, abundantly found in the cell apex, and more electron-lucent vacuoles in the basal region compared with those from untreated insects. Moreover, imidacloprid interfered with the differentiation of regenerative cells, dramatically reducing the number of digestive and endocrine cells and leading to malformation of the midgut epithelium in adults. The data demonstrate that imidacloprid can reduce the survival of mosquitoes and thus indicate its potentially high efficacy in the control of St. aegypti populations.

Synergism of Entomopathogenic Nematode and Imidacloprid: A Curative Tool to Coconut white Grub,Leucopholis coniophora(Coloeptera: Melolonthinae)

Insecticide imidacloprid and entomopathogenic nematode (EPN), Heterorhabditis indica alone and in combinations of imidacloprid and EPN were evaluated against early and late 3rd instars of coconut white grub, Leucopholis 3rd coniophora. Field collected instars white grubs were placed in pots with sweet potato treated with imidacloprid, the EPN, or both. In all nematode-imidacloprid combinations, both early and late 3rd instars grub mortality was significantly higher than in the H. indica alone and imidacloprid alone treatments. Combinations of imidacloprid and nematodes had a strong synergistic effect on mortality at different concentrations of imidacloprid. Nematodes were admixed with various concentrations of imidacloprid ranging from 0.04 to 1.25% could not significantly affect the survival of infective juveniles resulting in only a negligible mortality (3.5%). Results revealed that different imidacloprid concentrations, exposure time and interaction between imidacloprid and exposure time not affected nematodes mortality in bioassay. Combinations of imidacloprid and entomopathogenic nematodes may provide a powerful and economically feasible curative control in white grub management in coconut.

Synergistic effect of imidacloprid combined with synergistic agents (Beichuang, Jiexiaoli) on Myzus persicae (Hemiptera: Aphididae)

Myzus persicae is a well known aphid pest, which can transport plant viruses to plants of the nightshade/potato family, namely the Solanaceae, and other food crops. Our aim was to explore the effects of imidacloprid combined with synergistic agents (Beichuang and Jiexiaoli) on Myzus persicae. Different concentrations of imidacloprid combined with synergistic agents were used to treat M. persicae. Biological activity of M. persicae was analyzed under indoor conditions, and the control efficiency of the admixture was determined through field experiments. The penetration rate of the admixture on tobacco leaf and M. persicae was analyzed, and the liquid surface tension and contact angle was measured. Imidacloprid combined with Beichuang and Jiexiaoli showed significant synergistic effects with high control efficacy. Beichuang and Jiexiaoli significantly improved the penetration of imidacloprid into the cuticle of tobacco leaves and the insect body wall. The surface tension and contact angles were abated by synergists. The combination of imidacloprid with Beichuang and Jiexiaoli showed a significant synergistic effect, which can be used for decreasing the dosage of imidacloprid and improving its long-term control efficacy.

低剂量杀虫剂对星豹蛛捕食效应的影响及其机理初探

PDF HTML阅读 XML下载 导出引用 引用提醒 低剂量杀虫剂对星豹蛛捕食效应的影响及其机理 DOI: 10.5846/stxb201307241940 作者: 作者单位: 山西农业大学农学院,山西农业大学研究生学院,山西农业大学农学院,山西农业大学资源环境学院,山西农业大学农学院 作者简介: 通讯作者: 中图分类号: X503.1 基金项目: 中国博士后基金（112125）；山西省科技攻关项目（20130311011-5，20120311013-4）；山西省留学基金项目（2013-重点6） The effect of low-dose of pesticide on predation of spider and its preliminary mechanisms Author: Affiliation: College of Agronomy,Shanxi Agricultural University,,College of Agronomy,Shanxi Agricultural University,College of Resources and Environment,Shanxi Agricultural University,College of Agronomy,Shanxi Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:探讨低剂量杀虫剂对蜘蛛捕食效应的影响及其生化机理。采用药膜法，测定了低剂量吡虫啉作用下，星豹蛛和甘蓝蚜敏感性、捕食效应以及成蛛体内乙酰胆碱酯酶（AChE）、谷胱甘肽S-转移酶（GSTs）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和中肠蛋白消化酶的活力变化。低剂量农药作用下，星豹蛛对甘蓝蚜的功能反应类型为HollingⅡ型，与对照组相比，随着猎物密度的增大星豹蛛的捕食量增加，寻找效应降低，对猎物的处理时间Th缩短，从而增强了对猎物的捕食作用；低剂量农药处理后，星豹蛛体内AChE和GSTs活性均显著低于对照组（P < 0.05），说明酶活性受到抑制，且抑制作用随吡虫啉浓度的增大而加强，随作用时间的延长而减弱；SOD，CAT和中肠蛋白消化酶活性显著增强，与对照组相比存在显著或极显著差异（P < 0.05），且随吡虫啉浓度增大和作用时间的延长而逐渐降低，最后接近对照组。低剂量杀虫剂作用下，蜘蛛体内AChE活性受到抑制，AChE敏感性降低，对神经递质乙酰胆碱的分解作用下降，使蜘蛛的兴奋性增加；GSTs、SOD、CAT等代谢酶活性发生变化，使蜘蛛的新陈代谢加速，从而刺激捕食；中肠蛋白消化酶的活性增强，提高了对猎物的消化吸收功能。总之，在低剂量杀虫剂作用下，星豹蛛通过外在的捕食行为和体内一系列酶系生理生化反应的综合作用促进蜘蛛对害虫的控制作用。 Abstract:Spiders are among the most abundant predators of insects and other invertebrates in agro- and forest ecosystems, playing an important ecological role by regulating invertebrate populations. Biological control using spiders may represent a sustainable method of controlling agricultural pest species and reducing the amount of pest damage on crops. However, pesticide application on agricultural crops may directly or indirectly impact spider foraging in the crop. In particular, pesticides may have mutagenic effects on spiders, negatively affecting the spider population abundance and transferring these effects to the next generation. Recent studies have reported that low-dose pesticides kill pests, but promote the predation of natural enemies. Therefore, revealing the mechanism behind low-dose pesticides on natural enemies is critical to improving predator ability, exploring the potential control of insect predators and coordinating bio- and chemical control.Our aim was to investigate the effect of low-dose pesticides on spider predation behavior and reveal the underlying mechanisms. Pardosa astrigera was treated with a low-dose of imidacloprid using the drug-film method. We determined the sensitivity of P. astrigera, the predation effect of P. astrigera on B. brassicae and the activity of acetylcholinesterase (AChE), glutathione S-transferase (GSTs), superoxide dismutase (SOD), catalase (CAT) and midgut proteinase. The results showed that under different concentrations of imidacloprid, the predacious functional response of spiders on aphids belonged to the Holling type. Compared with the control, the theoretical maximal consumption increased, searching efficiency decreased and the prey handling time declined with increasing aphid density. Therefore, low-dose pesticide levels resulted in enhanced predation by spiders. When P. astrigera was treated with a low-dose of pesticide, this species showed a reduction in AChE and GSTs activity compared with the control (P < 0.05), suggesting spider activity was inhibited. The inhibition was enhanced with increasing pesticide concentration and weakened with prolonged treatment. SOD, CAT and midgut proteinase activity were induced significantly at the low-dose of 1, 3 and 5mg/L(P < 0.050, but decreased gradually with increased concentration and extended treatment, with activity close to the control. After low-dose pesticide treatment, P. astrigera showed inhibited AChE activity, leading to reduced AChE sensitivity, less decomposition of AChE in nerve transfer and increased spider activity. Increased GSTs, SOD and CAT activity induced by low-dose pesticide, accelerated the spiders' metabolism, stimulating predatory behavior. Enhanced midgut proteinase activity may benefit food digestion and nutrient absorption. The low-dose pesticide regime may enhance the predatory behavior of P. Astrigera via three main pathways. First, it enhances the instant attack rate, shortens prey handling time and increases the amount of prey per day. Second, it affects physiological enzyme activity, inhibits to a degree the metabolic detoxification enzyme subject of: low doses of imidacloprid causing a reduction in AChE sensitivity of the neurotransmitter acetylcholine decomposition, resulting in higher spider excitability; increased protection enzyme, such as GSTs, SOD, CAT, function oxidases (MFOs) and esterase, resulting in the acceleration of spider metabolism, stimulating predator behavior. Third, on the physiological activity of digestive enzymes, low doses of pesticides activate protein midgut digestive enzymes, improving the digestion and absorption function of prey. In summary, certain concentrations of pesticide promote the predation function of P. astrigera against prey, changing spider behavior through a series of physiological and biochemical reactions. 参考文献 相似文献 引证文献

Imidacloprid Affects Pardosa Pseudoannulata Adults and Their Unexposed Offspring

Imidacloprid is a nicotine-based, systemic, widely used insecticide. In order to investigate the effects of imidacloprid on the spider Pardosa pseudoannulata (Araneae: Lycosidae), specimens were exposed to different concentrations of imidacloprid (12.5, 25, 50, 100, 200 mg/L) by the dipping method. Surviving spiders were used to determine the fecundity, development time of unexposed offspring, predation, and the activities of detoxification enzymes. Significant reductions were observed in survival rate and fecundity of spiders exposed to imidacloprid. The development times of unexposed offspring (F(1)) were prolonged significantly with increased concentrations of imidacloprid. Spiders exposed to concentrations of imidacloprid above 25 mg/L showed significantly weaker predation on Drosophila melanogaster than the control group, but a low dose of imidacloprid (12.5 mg/L) increased predation ability. The activities of carboxyl esterase, acetyl cholinesterase, and the mixed-function oxidase were significantly inhibited by imidacloprid. With increasing concentrations of imidacloprid, the activities of all three kinds of enzymes were decreased significantly. These results suggest that imidacloprid can stimulate the performance of spiders (in low concentration) and has chronic toxicity to the spiders.

Insecticide-Induced Changes in Protein, RNA, and DNA Contents in Ovary and Fat Body of Female &lt;I&gt;Nilaparvata lugens&lt;/I&gt; (Hemiptera: Delphacidae)

The widespread use of insecticides is known to cause resurgence in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) populations, a serious insect pest of rice, Orzya sativa L., crops in Asia. The current study investigated insecticide-induced changes in protein, RNA, and DNA levels in the ovary and fat body of adult female N. lugens. Potted rice plants were sprayed with different concentrations of imidacloprid, triazophos, and detamethrin. The results showed that all three insecticides caused a significant increase in protein and RNA contents in the ovary and fat body of adult females developed from nymphs fed on treated plants compared with those from on untreated plants, although there was no significant effect on DNA content. In general, protein and RNA contents in both ovary and fat body increased linearly with insecticide concentrations or days after emergence (DAEs) when they were applied. There was a significant correlation between protein content and RNA content in both ovary and fat body. In addition, the relationship between ratios of RNA to protein in ovary and fat body of adult female N. lugens and insecticide concentrations showed a significant positive correlation for most DAEs of imidacloprid and several DAEs of triazophos and deltamethrin treatments. These findings suggest that RNA in both ovary and fat body was more sensitive to insecticides and that the insecticide-induced changes in RNA content in turn influence protein synthesis in ovary and fat body. Consistently, RNA-to-protein ratios in ovary and fat body were approximately 0.42 in all treatments and controls.

Toxicity of Four Systemic Neonicotinoids to Adults of &lt;I&gt;Anoplophora glabripennis&lt;/I&gt; (Coleoptera: Cerambycidae)

As part of the ongoing evaluation of different systemic insecticides for prophylactic treatment of trees, responses of the beetle Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) to different doses of four systemic neonicotinyl insecticides were studied. Adult beetles were provided with twigs or leaves of trees treated with different concentrations of imidacloprid to evaluate the toxicity of the insecticide through ingestion or contact or through both. Adult beetles also were provided with twigs of host plant treated with clothianidin, dinotefuran, and thiamethoxam to establish dose response of the beetle to these insecticides. Levels of individual insecticides in twigs and leaves were determined by using the "parent" method with high-performance liquid chromatography, and these levels were compared with the applied concentrations to determine their relationship. The LC50 values for detected level of each insecticide in twigs was 5.1 ppm at 24 h, 2.9 at 48 h, and 1.9 ppm at 72 h for imidacloprid; 1.1 ppm at 72 h for clothianidin; 2.2 ppm at 72 h for dinotefuran; and 1.0 ppm at 72 h for thiamethoxam. Our results indicate that mortality of adult beetles resulted not only from the ingestion and contact toxicity but also possibly from the antifeedant effect of imidacloprid.

Toxicity of Four Systemic Neonicotinoids to Adults of Anoplophora glabripennis (Coleoptera: Cerambycidae)

As part of the ongoing evaluation of different systemic insecticides for prophylactic treatment of trees, responses of the beetle Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) to different doses of four systemic neonicotinyl insecticides were studied. Adult beetles were provided with twigs or leaves of trees treated with different concentrations of imidacloprid to evaluate the toxicity of the insecticide through ingestion or contact or through both. Adult beetles also were provided with twigs of host plant treated with clothianidin, dinotefuran, and thiamethoxam to establish dose response of the beetle to these insecticides. Levels of individual insecticides in twigs and leaves were determined by using the “parent” method with high-performance liquid chromatography, and these levels were compared with the applied concentrations to determine their relationship. The LC50 values for detected level of each insecticide in twigs was 5.1 ppm at 24 h, 2.9 at 48 h, and 1.9 ppm at 72 h for imidacloprid; 1.1 ppm at 72 h for clothianidin; 2.2 ppm at 72 h for dinotefuran; and 1.0 ppm at 72 h for thiamethoxam. Our results indicate that mortality of adult beetles resulted not only from the ingestion and contact toxicity but also possibly from the antifeedant effect of imidacloprid.