Lack of fitness cost and inheritance of resistance to abamectin based on the establishment of a near-isogenic strain of Tetranychus urticae

Many populations of the two-spotted spider mite, Tetranychus urticae Koch, have developed high levels of resistance to the pesticide abamectin in China and other countries. This study developed a near-isogenic line to understand better the inheritance, cross-resistance, and fitness costs associated with abamectin resistance in the field population of T. urticae in China. We introduced the trait that confers extremely high abamectin resistance in a field-collected population of T. urticae into a susceptible laboratory strain(IPP-SS) to generate an abamectin-resistant near-isogenic line(NIL-Aba).This process was carried out through multiple backcrossing to IPP-SS and via parthenogenesis and abamectin screening. Compared with IPP-SS, the NIL-Aba strain had a 25 147-fold resistance to abamectin and a high level of cross-resistance to bifenthrin(288.17-fold), an intermediate level to emamectin benzoate(42.57-fold), and low levels to bifenazate, chlorfenapyr, cyflumetofen, cyenopyrafen, and cyetpyrafen with resistance ranging from 3.18-to 9.31-fold.But it had no cross-resistance to profenofos. The resistance to abamectin in NIL-Aba was autosomal, incompletely dominant, and polygenic. Based on two sex life table parameters, no fitness cost was found in NIL-Aba. Establishing the NIL-Aba strain provides a reliable basis for an in-depth study of abamectin resistance in T. urticae. New information on toxicological characteristics and fitness cost should facilitate the management of abamectin resistance in field populations of T. urticae.

Study on the Toxicity Effect of Abamectin and Chlorpyrifos on Grass Carp(Ctenopharyngodon idllus)

[ Objective] The study aimed to discuss the toxicity effect of abamectin and ehlorpyrifos on grass carp （ Ctenopharyngdon idllus ） and their interrela- tions. [ Method] Taking healthy and active grass carp as the object, the acute toxicity test of single pesticide and the combined toxicity test of two pesticides on grass carp were carried out. [ Result] The LC50 of abamectin and chlorpyrifes and the mixture of two pesticides against grass carp at 24, 48, 72 and 96 h were as follows： abamectin： 0.54, 0.49, 0. 17 and 0.10 rag/L; chlorpyrifes ： 0.29, 0.21, 0.12 and 0.05 rag/L; the mixture of two pesticides ： 1.22, 1.08, 0.99 and 0. 86 mg/L. The safe concentration （SC） of ahamectin, chlorpyrifos and the mixture of two pesticides were 0.010, 0.005 and 0.086 rag/L, respectively. The tox- icity of the pesticides in sequence was ablorpyrifos 〉 ahamectin 〉 the mixture of two pesticides. [ Conclusion ] Different concentrations of abamectin, chlorpyrifos and the mixture of two pesticides had remarkable effect on the growth of grass carp, the higher the concentration was, the greater the toxicity effect was. Ahamectin at low toxicity intensity had certain relief function on the toxicity of ehlorpyrifos.

Aba mectin与几种杀虫杀螨剂及其混剂对棉叶螨的室内毒力测定

采用FAO( 1 980 )推荐的浸玻片法 ,室内对Abamectin、三氯杀螨醇、氧化乐果、水胺硫磷及Abamectin与三种杀虫杀螨剂分别按 1∶5 0、1∶1 0 0、1∶2 0 0的比例制成的混剂对抗性棉叶螨(抗久效磷品系 ,抗性系数为 1 3.1 6)进行毒力测定。结果表明 ,Abamectin、三氯杀螨醇、氧化乐果、水胺硫磷的LC50 值分别为 3.392 0× 1 0 - 2 μg/ml、2 .31 75 μg/ml、1 38.83μg/ml和 2 0 395 μg/ml;Abamectin与三氯杀螨醇 1∶5 0 ,1∶1 0 0均表现出拮抗作用 ,CTC值分别为 65 .1 0和72 .2 7,Abamectin与氧化乐果和水胺硫磷的三个不同配比均表现不同程度的增效作用 ,1∶2 0 0的比例CTC值分别为 445 .96和 376.88。

ABAMECTIN与Bt制剂复配的杀虫增效作用

以菜青虫为试虫测定abamectin与Bt8010复配的毒力。结果表明abamectin—Bt8010的5种不同配比均有不同程度的增效作用,其中以5000IUBt8010+0.1％abamectin的增效作用最为显著,其共毒系数为289.4.室内药效测定结果,用该配比制成的可湿性粉剂对花椰菜、白菜、番茄、豌豆、蚕豆、茶树、柑桔、马尾松8种植物上分属鳞翅目、同翅目、鞘翅目、双翅目和蜱螨目的23种害虫有较好的杀灭效果。混配制剂对鳞翅目幼虫仅能提高用药24h后的杀灭率,并不能提高24h内的杀灭速度。

Genotoxicity of Three Avermectins on Polypedates megacephalus Tadpoles Using the Comet Assay

Avermectins are a new class of macrocyclic lactones derived from mycelia of the soil actinomycete, and are used as effective agricultural pesticides and antiparasitic agents. However, run-off from crops treated with avermectins may contaminate various bodies of water, and accumulated to certain concentrations to impact the development of aquatic animals. Here, we tested the genotoxicity of three avermectins （abamectin, ABM; ivermectin, IVM; and emamectin benzoate, EMB） on Polypedates megacephalus tadpoles by the alkaline single-cell gel electrophoresis assay. Tadpoles were treated for 48 h in the laboratory with different concentrations of these three agents, 0.006, 0.012, 0.018, 0.024, 0.030 mg/L for ABM, 0.003, 0.006, 0.009, 0.012, 0.015 mg/L for IVM and 0.04, 0.06, 0.08, 0.10, 0.12 mg/L for EMB, and then measured their DNA damage by the Comet assay tail factor %. The concentrations of resulted in highly significant increases in DNA damage of the tadpoles were found above the concentration threshold of 0.012 mg/ L ABM, 0.003 mg/L IVM and 0.06 mg/L EMB and linear correlations between the intensity of DNA damage and the concentrations of these three avermectins. Our results showed clearly that avermectins caused dose dependent DNA damage on amphibian tadpoles, and there might be a control on the misuse of avermectins.

家蝇对Abamectin的抗性

<正> Abamectin是一组具有强大杀螨、杀虫、杀线虫活性的十六员大环内酯,是一种土壤放线菌Strepto-mycesavermitilis的天然发酵产物,即四种极相似的同系物:AbamectinA1,A2,B1和B2。其中Abamect-inB1（Abamectin,MK-936）是从液体发酵产物中分离

In vitro Acute Cytotoxicity of Abamectin to the Gill Cell Line of Flounder Paralichthy olivaceus

The cytotoxicity of abamectin to the Gill Cell Line of Flounder （FG cell line） was examined in this study. It was found that the exposure of FG cells to abamectin caused the decreases of both cell growth rate and antioxidant enzyme activities, and the increase of intracellular 02 content. It was proposed that the reduction of antioxidant enzyme activities in FG cells caused the accumulation of 02 content in FG cells, leading to the change of cell morphology and even the death of cells. The results showed that FG cell line is suitable for the evaluation of the acute toxicity of abamectin.

Efficacy Evaluation of 25% Abamectin·Etoxazole SC against Red Spider (Tetranychus cinnbarinus ) in Ornamental Rose

[Objective]The paper was to understand the control effect and the optimum dosage of 25% abamectin·etoxazole SC for controlling red spider in ornamental rose. [Method] Using stem-leaf spraying method,the control effect of 25% abamectin·etoxazole SC against red spider was determined. Significance of difference was examined by Duncan's new multiple range test( DMRT). [Result] The control effect of 25% abamectin · etoxazole SC sprayed at the dose of25-31. 25 mg a. i./kg on red spider was over 82. 0% at 21 d post spraying,higher than that of 110 g/L etoxazole SC sprayed at the dose of 27. 5 mg a. i./kg and1. 8% abamectin EC sprayed at the dose of 9 mg a. i./kg. [Conclusion]25% Abamectin·etoxazole SC sprayed at the doses of 25-31. 25 mg a. i./kg could effectively control the damage of red spider in ornamental rose,and can be widely used in production.

Integrated Control of Tetranychus cinnabarinus by Five Kinds of Pesticides Combined with Neoseiulus cucumeris

To find the method for the integrated control of Tetranychus cinnabarinus （carmine spider mite） and delay its resistance to pesticides, the joint actions of each of five commonly pesticides （abamectin, azadirachtin, matrine, pyrethrins and imidacloprid）, and Neoseiulus cucumeris （Oudemans）, the natural enemy of cotton red spider mite, were studied. N. cucumeris was released after application of pesticides for seven days （for 0,3% azadirachtin EC） or six days （for other pesticides）. The results showed that the combined action of 1.8% abamectin EW （1：8 000） and N. cucumeris had the best control efficacy of 96.63% at 20 days after N. cucumeris releasing. The control efficacies of N. cucumeds and 0.3% azadirachtin EC （1：250） were 59.7% and 90.1% after one day and 20 days, respectively, after N. cucumeris releasing. The control efficacy of N. cucumeris and 0.5% matrine AS （1：2 000） was 82.65% at 20 days after N. cucumeris releasing. The results provide options for sustainable control of T. cinnabarinus and for the delay of pesticides resistance.

Comparative Toxicity of Selected Insecticides to Phytoplasma Transmitted Leafhopper Cicadulina bipunctata （Melichar）

Leafhopper Cicadulina bipunctata is represented the main insect as a pathogen for phytoplasma disease occurring by insect-transmitted plant viruses in date palm orchards. Therefore, it is important to investigate the potential effect of some insecticides against such insect. The adults of leafhopper C. bipunctata were collected from date palm orchards in Alhasa, Eastern province, Saudi Arabia. Three insecticides from different classes--beta-cyfluthrin （pyrethroids）, imidacloprid （neonicotinoids） and abamectin （natural compounds）--have been evaluated in vivo against adults C. bipunctata. This stage was exposed to residual film of various concentrations of each insecticide on transparent plastic cups using a Potter precision laboratory spray tower. Bioassay test showed that both beta-cyfluthrin and imidacloprid caused 100% mortality by 500 ppm at 24 h after treatment, whereas abamectin gave the same mortality by 50 ppm at the same time. Toxicity values revealed that abameetin was the most potent insecticide compared with beta-cyfluthrin and imidacloprid, where the lethal concentrations LC50 and LC95 were 24.58 ppm and 116.73 ppm at 3 h after treatment, respectively. Therefore, abamectin can be a possible candidate to be applied on date palm or ground grass by the Ministry of Agriculture after successful field experiments.

Effect Trials on Abamectin + Chlorpyrifos 8% GR for Controlling Turf Grubs

To screen high-efficiency, low-toxicity, and safe pesticides for controlling soil pests, experimental investigations of Abamectin ＋ Chlorpyrifos 8 % GR for controlling tuff grubs were implemented according to Field Pharrnacodynamic Test Standards of the Ministry of Agricuhure. The results showed that as the active in- gredient of Abamectin ＋ Chlorpyrifos 8% GR is 1 625 - 1 950 g/hm2, the control efficiency of tuff grubs is 81.43% -90.46% 3 - 10 days after pesticide applica- tion, the readily availability and persistent effect achieve the ideal level, and it is safe for turf.

The Role of Ethanolic Extracts of Leaves and Roots of <i>Lantana camara</i>(L.) in the Management of Pests of Okra <i>Abelmoschus esculentus</i>(L.) Moench

The cultivation of many crops in Africa is negatively affected by a number of constraints, the most important of which is the incidence of pests and diseases. In many areas of the world, the most preferred option in the management of pests is the application of synthetic chemical pesticides. Due to the negative effects of pesticides on humans and the environment as a whole, efforts are being made to find alternatives for pest management. Ethanolic extracts of the leaves and roots of Lantana camara were tested against the major pests of okra, Abelmoschus esculentus. The plant extracts were compared with a standard chemical insecticide, Mektin (a.i 18 g/L abamectin) in a randomly complete block design with four treatments and three replications. Parameters studied included the major pests of the plant and the damage caused, leaf area, plant height as well as yield of okra. Cotton aphids, Aphis gossypii, the tobacco whitefly Bemisia tabaci and the cotton flea beetle, Podagrica puncticollis were the major pests encountered on okra plants. Aphis gossypii and B. tabaci populations were significantly lower on the L. camara-sprayed plots compared with the control plots. Similarly, P. puncticollis numbers were significantly smaller on the L. camara-sprayed plots than the control plots. There were no significant differences between the treatments and the control for plant height, leaf area and yield. The significant reduction in pests numbers on the L. camara-sprayed plots indicates its potential as an alternative to chemical insecticides, thereby reducing the reliance on chemical insecticides in the management of insect pests.

Short-Time Derivatization Method for Analysis of Abamectin in Water Using High-Performance Liquid Chromatography Coupled to Fluorescence Detector

A method using a short-time derivatization step for the assessment of abamectin in water is presented. Abamectin derivative stable up to 7 days was obtained. Some regions where orange crops are present have received abamectin doses, aiming to increase the productivity and to combat pests and weeds, even when its residues reach the aquatic environment and interfere on water quality. Water samples from Jacaré-Pepira River (Brotas City, Brazil) nearby orange crops around urban zone, were evaluated for the presence of abamectin. The analytical method was validated resulting recovery around 108%, precision of 12%, accuracy of 104%, correlation coefficient of 0.9945, and detection and quantification limits of 0.1 μg·L﹣1 and 0.2 μg·L﹣1, respectively. Stable abamectin derivative was reached after 60 min of derivatization at room temperature (25&deg;C). No abamectin residues were found into samples.

Increased expression of CSP and CYP genes in adult silkworm females exposed to avermectins

We analyzed 20 chemosensory protein （CSP） genes of the silkworm Bombyx mori. We found a high number of retrotransposons inserted in introns. We then analyzed expression of the 20 BrnorCSP genes across tissues using quantitative real-time polymerase chain reaction （PCR）. Relatively low expression levels of BmorCSPs were found in the gut and fat body tissues. We thus tested the effects of endectocyte insecticide abamectin （B 1 a and Blb avermectins） on BmorCSP gene expression. Quantitative real-time PCR experi- ments showed that a single brief exposure to insecticide abamectin increased dramatically CSP expression not only in the antennae but in most tissues, including gut and fat body. Furthermore, our study showed coordinate expression of CSPs and metabolic cytochrome P450 enzymes in a tissue-dependent manner in response to the insecticide. The function of CSPs remains unknown. Based on our results, we suggest a role in detecting xenobiotics that are then detoxified by cytochrome P450 anti-xenobiotic enzymes.

The expression of Spodoptera exigua P450 and UGT genes: tissue specificity and response to insecticides

Cytochrome P450 and UDP-glucosyltransferase (UGT) as phase I and phase II metabolism enzymes, respectively, play vital roles in the breakdown of endobiotics and xenobiotics. Insects can in crease the expression of detoxificatio n enzymes to cope with the stress from xenobiotics including insecticides. However, the molecular mechanisms for insecticide detoxification in Spodoptera exigua remain elusive, and the genes conferring insecticide metabolisms in this species are less well reported. In this study, 68 P450 and 32 UGT genes were identified. Phylogenetic analysis showed gene expansions in CYP3 and CYP4 clans of P450 genes and UGT33 family of this pest. P450 and UGT genes exhibited specific tissue expression patterns. Insecticide treatments in fat body cells of S. exigua revealed that the expression levels of P450 and UGT genes were significantly influenced by challenges of abamectin, lambda-cyhalothrin, chlorantraniliprole, metaflumizone and indoxacarb. Multiple genes for detoxification were affected in expression levels after insecticide exposures. The results demonstrated that lambda-cyhalothrin, chlorantraniliprole, metaflumizone and indoxacarb induced similar responses in the expression of P450 and UGT genes in fat body cells;eight P450 genes and four UGT genes were co-up-regulated significantly, and no or only a few CYP/UGT genes were down-regulated significantly by these four insecticides. However, abamectin triggered a distinct response for P450 and UGT gene expression;more P450 and UGT genes were down-regulated by abamectin than by the other four compounds. In con elusion, P450 and UGT genes from S. exigua were identified, and different responses to abamectin suggest a different mechanism for insecticide detoxification.

Functional analysis of UG7207D3 associated with abamectin resistance in Tetranychus cinnabarinus(Boisduval)

Uridine diphosphate(UDP)-glycosyltransferases(UGTS)are widely distributed within living organisms and share roles in biotransformation of various lipophilic endo-and xenobiotics with activated UDP sugars.In this study,it was found that the activity of UGTs in abamectin-resistant(AbR)strain was significantly higher(2.3-fod)than that in susceptible strain(SS)of Tetramychus cinnabarinus.Further analysis showed that 5-nitrouracil,the inhibitor ofUGTs,could enhance the lethal effect of abamectin on mites.From the previous microarray results,we found an UGT gene(UGT201D3)overexpressed in AbR strain.Quantitative PCR analysis showed that UGT20ID3 was highly expressed and more inducible with abamectin exposure in the AbR strain.After silencing the tran-scription of UGT201D3,the activity of UGTs was decreased and the susceptibility to abamectin was increased in AbR strain whereas it was not in sS.Furthermore,UGT201D3 gene was then succefully expressed in Escherichia coli.The recombinant UGT20ID3 exhibited a-naphthol activity(2.810.43 nmol mg protein/min),and the enzyme activity could be inhibited by abamectin(inhibitory concentration at 50%:57.50±3.54 μmol/L).High-performance liquid chromatography analysis demonstrated that the recombinant UGT201D3 could efctively deplete abamectin(15.77%±3.72%)incubating with 150 ug protein for 6 h.These results provided direct evidence that UGT201D3 was involved in abamectin resistance in T cinnabarinus.

Low temperature purification method for the determination of abamectin and ivermectin in edible oils by liquid chromatographytandem mass spectrometry

In this study, a method based on low temperature purification （LTP） coupled with liquid chromatography-tandem mass spectrometry （LC-MS/MS） was developed for the determination of abamectin （ABA） and ivermectin （IVR） in edible oils. ABA and IVR were extracted using conventional liquid-liquid extraction followed by purification via precipitation of interfering fatty components at low temperature without an additional cleanup step. LTP is simple, easy to use, labour-saving and cost effective, and requires reduced amounts of organic solvent. The linear ranges of ABA and IVR were 5- 1000 t^g/L using matrix-matched standards. Limits of detection （LOD） and limits of quantification （LOQ） were in the range of 0.1-0.4 i^g/kg and 0.3-1.3 p^g/kg, respectively. The LOQs were below the strictest maximum residue limits established by Codex Alimentarius Commission. Recoveries at three spiked levels of 10, 20 and 100 i^g/kg in peanut oil, corn oil, olive oil, soybean oil and lard ranged from 71.1% to 119.3% with relative standard deviations of 3.2%-10.3%, which were in agreement with those obtained by the solid phase extraction method. The proposed method was utilized in the analysis of 10 edible oil samples from local market and neither ABA nor IVR was detected. As far as we know, this is the first time that LTP is applied to the determination of avermectins in edible oils.

Acute toxicity test of pesticide abamectin on common carp(Cyprinus carpio)

Objective:To determine acute toxicity of abamectin(abamectin used for agricultural fields and also is a common acaridae used in farms)to common carp(Cyprinus carpio).Methods:In this research,common carps were exposed to abamectin for 96 h.LC_(50) values of 24 h,48 h,72 h and 96 h were attained by probit analysis software SPSS Version 16.Fish were exposed to different concentrations(1,2,3,6,12 and 15 mg/L)of abamectin for 96 h and physicochemical properties of water used for these experiments were stable and every mortality was recorded daily.Results:The 96 h LC_(50)of abamectin for Cyprinus carpio was 1.243 mg/L.Conclusions:Eventually toxicity values indicated that abamectin has same toxicity in studied other specie and we can state lower value of LC_(50)for studied specie in compare with most species.

Abamectin resistance in strains of vegetable leafminer, Liriomyza sativae （Diptera： Agromyzidae） is linked to elevated glutathione S-transferase activity

Abamectin resistance was selected in the vegetable leafminer, Liriomyza sativae （Blanchard） （Diptera： Agromyzidae） under laboratory conditions, and cross- resistance patterns and possible resistance mechanisms in the abamectin-resistant strains （AL-R, AF-R） were investigated. Compared with the susceptible strain （SS）, strain AL-R displayed 39-fold resistance to abamectin after 20 selection cycles during 25 generations, and strain AF-R exhibited 59-fold resistance to abamectin after 16 selection cycles during 22 generations. No cross-resistance to cyromazine was found in both abamectin-resistant strains. However, we failed to select for cyromazine resistance in L. sativae under laboratory conditions by conducting 17 selection cycles during 22 generations. However, moderate levels of cross-resistance to abamectin （6-9 fold） were observed in strains which received cyromazine treatments. Biochemical analysis showed that glutathione S-transferase （GST） activity in both abamectin-resistant strains （AL-R, AF-R） was significantly higher than in the susceptible strain （SS）, suggesting metabolically driven resistance to abamectinin L. sativae. Recommendations of mixtures or rotation of cyromazine and abamectin should be considered carefully, as consecutive cyromazine treatments may select for low-level cross-resistance to abamectin.

Influences of insecticides on toxicity and cuticular penetration of abamectin in Helicoverpa armigera

Synergistic actions for mixtures of abamectin with other insecticides in some insect pests were evaluated, and the possible synergistic mechanism was studied by the comparison in toxicity and cuticular penetration of abamectin between with and without other insecticides or synergists in Helicoverpa armigera larvae. The results of bioassay showed that horticultural mineral oil (HMO), hexaflumuron, chlorpyrifos, and some other insecticides were synergistic to abamectin with 152.0-420.0 of co-toxicity coefficient(CTC) in some agricultural insect pests. In topical application tests, HMO or piperonyl butoxide (PBO) increased the toxicity of abamectin in larvae of H. armigera, but the mortality was not affected by s,s,s-tributylphorotrithioate (DEF) and triphenylphosphate (TPP). The synergistic action of HMO was obviously higher than PBO, and when treated simultaneously with abamectin, HMO gave a more significant synergism than if treated 2 hours ahead. The highest synergistic effect (SE) was found in the mixture of ‘abamectin+HMO (1:206)'. The mortality did not increase or the toxicity drop, when a synergist or HMO was added into the mixture of ‘abamectin+HMO' or ‘abamectin+synergist', respectively. Results from the isotope tracing experiments showed that HMO significantly enhanced the penetration of ^3H-abamectin through the cuticle of H.armigera larvae, which resulted in the synergism of the mixture. The cuticular penetration of ^3H-abamectin was not accumulatively affected by chlorpyrifos, nor by hexaflumuron,though there was an inhibition within 30 seconds or 1 hour after treated by these two chemicals respectively. Results suggested that the synergism of abamectin mixed with hexaflumuron or chlorpyrifos might be related to inhibition of metabolic enzymes or target sites in the larvae.