Abamectin Research Articles

Evaluation of abamectin induced hepatotoxicity in Oreochromis mossambicus

Abamectin (ABM) is a naturally fermented product of Streptomyces avermitilis. It is used to control pests in livestock and agriculture. In the present study, it has been hypothesized that intoxication of ABM to Oreochromis mossambicus impairs the function of the hepatocyte. Fishes were exposed to ABM with 40, 45, and 55 ppb for 48 h. Test animals were observed at regular intervals of time and sacrificed at the end of the regimen. Liver function tests, oxidative stress parameter, and histopathological alterations were taken into account to analyze hepatotoxicity induced by the test compound. Plasma transaminase activities were increased significantly in all the treated groups. The activity of lipid peroxidation was measured higher due to ABM intoxication, whereas catalase activity was depleted. The marked focal necrotic alteration was examined in liver tissue. The low-dose group showed a less adverse effect on liver, whereas the medium and high dose induced moderate-to-severe hepatotoxicity. Data from this study demonstrate that ABM exposure generates reactive oxygen species (ROS) and alter liver function of fishes, which may lead to liver necrosis. The authors’ emphasis on the regulatory use of ABM to protect fish health against ABM-induced toxicological effects.

Removal of abamectin and conventional pollutants in vertical flow constructed wetlands with Fe-modified biochar.

To improve the ability of constructed wetlands to remove abamectin (ABM) and nutrients, the influence of four different substrates on constructed wetlands was studied. Four vertical up-flow constructed wetlands (UVCWs) were established to treat simulated agricultural wastewater: CW1 (quartz sand + pebbles), CW2 (pebbles + coke), CW3 (Fe-modified biochar + pebbles + coke), and CW4 (unmodified biochar + pebbles + coke). Under different combinations of hydraulic loading and organic loading, CW3 was extremely effective at removing nitrogen compared with CW1, CW2 and CW4. We found that CW3 was the most effective at treating ABM and conventional pollutants. The highest efficiency of removal of abamectin (99%), COD (98%), NH4+–N (65%), and TP (80%) was obtained in CW3. These results were directly verified by microbiological tests and microbial community analysis. The microbial diversity of CW3 and CW4 was significantly higher than those of CW1 and CW2. Fe-modified biochar provides a feasible and effective amendment for constructed wetlands to improve the nitrogen removal for C/N (2.5 : 1–5 : 1) wastewater by the ability of microbes to remove nitrogen. Fe-modified bamboo charcoal can be used in engineering as a new type of green environmental protection constructed wetland filler in the future.

Interaction patterns and combined toxic effects of acetamiprid in combination with seven pesticides on honey bee (Apis mellifera L.)

The neonicotinoid insecticide acetamiprid (ACT) and seven pesticides [abamectin (ABA), emamectin benzoate (EMB), dicrotophos (DIC), bifenthrin (BIF), cypermethrin (CYP), lambda-cyhalothrin (LCY) and tetraconazole (TET)] are widely applied agrochemicals worldwide. Since most previous studies on these pesticides are performed merely based on toxicity tests with individual active ingredients, only finite knowledge is available on the mixture toxicities of these formulated compounds to crop pollinators. In this study, we examined their toxicities of binary, ternary, quaternary, quinquenary, senary, septenary and octonary mixtures to honey bee (Apis mellifera L.) with feeding toxicity test. Results showed that EMB and ABA had the highest toxicities to A. mellifera with LC50 values of 0.033 (0.028-0.038) and 0.047 (0.039-0.056) μg a. i. mL-1 after exposure for 7 days, respectively, followed by DIC with an LC50 value of 1.22 (1.01-1.41) μg a. i. mL-1. In contrast, relatively low toxicities were found from pyrethroid insecticides, ACT, and TET with their LC50 values ranged from 44.76 (38.75-50.89) to 251.7 (198.4-297.3) μg a. i. mL-1. Most of pesticide mixtures containing ACT and TET elicited synergistic interactions to honey bees. Besides, four pesticide mixtures of ACT+BIF, ACT+BIF+CYP, ACT+BIF+LCY and ACT+CYP+DIC+EMB also displayed synergistic effects. Among 98 tested binary to octonary mixtures of ACT in combination with seven pesticides, 44.90% of combinations exhibited synergistic effects on honey bees. Considering ACT was permitted to use on flowering crops, more attention should be paid to its application in the fields due to the synergistic effects of ACT in combination with other pesticides on A. mellifera under laboratory conditions.

Pharmacokinetic-pharmacodynamic assessment of the ivermectin and abamectin nematodicidal interaction in cattle

In a context of nematodicidal resistance, anthelmintic combinations have emerged as a reliable pharmacological strategy to control gastrointestinal nematodes in grazing systems of livestock production. The current work evaluated the potential drug-drug interactions following the coadministration of two macrocyclic lactones (ML) ivermectin (IVM) and abamectin (ABM) to parasitized cattle using a pharmacokinetic/pharmacodynamic (PK/PD) approach. The kinetic behavior of both compounds administered either separately or coadministered was assessed and the therapeutic response of the combination was evaluated under different resistance scenarios. In the pharmacological trial, calves received a single subcutaneous (s.c.) injection of IVM (100 μg/Kg); a single s.c. injection of ABM (100 μg/Kg) or IVM + ABM (50 μg/Kg each) administered in different injection sites to reach a final ML dose of 100 μg/Kg (Farm 1). Plasma samples were taken from those animals up to 20 days post-treatment. IVM and ABM plasma concentrations were quantified by HPLC. A parasitological trial was carried out in three farms with different status of nematodes resistance to IVM. Experimental animals received IVM (200 μg/Kg), ABM (200 μg/Kg) or IVM + ABM (100 μg/Kg each) in Farm 2, and IVM + ABM (200 μg/Kg each) in Farms 3 and 4. The anthelmintic efficacy was determined by fecal egg count reduction test (FECRT). PK analysis showed similar trends for IVM kinetic behavior after coadministration with ABM. Conversely, the ABM elimination half-life was prolonged and the systemic exposure during the elimination phase was increased in the presence of IVM. Although IVM alone failed to control Cooperia spp., the combination IVM + ABM was the only treatment that achieved an efficacy higher than 95% against resistant Cooperia spp. in all farms. In fact, when Cooperia spp. was the main genus within the nematode population and Haemonchus spp. was susceptible or slightly resistant to ML (Farms 2 and 4), the total FECR for the combination IVM + ABM was higher than 90%. Instead, when the predominant nematode genus was a highly resistant Haemonchus spp. (Farm 3), the total FECR after the combined treatment was as low as the single treatments. Therefore, the rational use of these pharmacological tools should be mainly based on the knowledge of the epidemiology and the nematode susceptibility status in each cattle farm.

Pesticide application has little influence on coding and non-coding gene expressions in rice

BackgroundAgricultural insects are one of the major threats to crop yield. It is a known fact that pesticide application is an extensive approach to eliminate insect pests, and has severe adverse effects on environment and ecosystem; however, there is lack of knowledge whether it could influence the physiology and metabolic processes in plants.ResultsHere, we systemically analyzed the transcriptomic changes in rice after a spray of two commercial pesticides, Abamectin (ABM) and Thiamethoxam (TXM). We found only a limited number of genes (0.91%) and (1.24%) were altered by ABM and TXM respectively, indicating that these pesticides cannot dramatically affect the performance of rice. Nevertheless, we characterized 1140 Differentially Expressed Genes (DEGs) interacting with 105 long non-coding RNAs (lncRNAs) that can be impacted by the two pesticides, suggesting their certain involvement in response to farm chemicals. Moreover, we detected 274 alternative splicing (AS) alterations accompanied by host genes expressions, elucidating a potential role of AS in control of gene transcription during insecticide spraying. Finally, we identified 488 transposons that were significantly changed with pesticides treatment, leading to a variation in adjacent coding or non-coding transcripts.ConclusionAltogether, our results provide valuable insights into pest management through appropriate timing and balanced mixture, these pesticides have no harmful effects on crop physiology over sustainable application of field drugs.

Immune response to abamectin-induced oxidative stress in Chinese mitten crab, Eriocheir sinensis

It is known that abamectin (ABM) inflicts oxidative damage on aquatic animals; however, knowledge about the immune response under pesticide-induced oxidative stress is incomplete. In the present study, several cellular and humoral immune parameters, including total haemocyte counts (THC), lysosomal membrane stability (LMS), activities of acid phosphatase (ACP), alkaline phosphatase (AKP) and lysozyme (LZM) were investigated to reveal the effects of ABM exposure on the immune defence mechanisms of the important freshwater crab, Erocheir sinensis. According to the results, a significant increase of THC was found in low concentration groups (0.03 and 0.06 mg/L), while dramatic decreases occurred in high concentration groups (0.12 and 0.24 mg/L) after 96 h of exposure. We also detected significant increases of reactive oxygen species (ROS) in haemocytes at 0.12 and 0.24 mg/L, and there was a dose- and time-dependent decrease of lysosomal membrane stability. These results suggest that the excessive generation of ROS induced by ABM may be leading the massive collapse of lysosomal membrane, which in turn may be causing the sharp drop of haemocyte counts in E. sinensis. The increase of hydrolytic enzymes ACP and AKP at low concentrations and the decrease at high concentrations also indicate an immune response associated with haemocytes status under stress. However, activities of LZM decreased significantly. After injection of Aeromonas hydrophil, mortalities increased under exposure to ABM and were positively related to ABM concentration. These results confirm that ABM exposure has the ability to impair immune defence and result in the host's susceptibility to pathogens.

The effects of abamectin on oxidative stress and gene expression in rat liver and brain tissues: Modulation by sesame oil and ascorbic acid

The present work was designed to assess the modulatory effects of sesame oil (SO) and ascorbic acid (AA) on abamectin (ABM)-induced oxidative stress and altered gene expression of hepatic cytochrome P450 2E1 (CYP-2E1), p38 MAPK, and caspase-3 and cerebral P-glycoprotein (Abcb1a receptor). Male rats were distributed into five groups (6 rats/group), receiving distilled water, ABM 2 mg/kg bwt 1/5 LD50 orally for 5 days, ABM + AA 100 mg/kg bwt orally, ABM + SO 5 ml/kg bwt orally, or ABM + SO + AA at the aforementioned doses. Nineteen compounds were identified in the SO sample by GC–MS analysis, including tetradecane,2,6,10-trimethyl, octadecane, 1-hexadecanol,2-methyl, and octadecane,6-methyl. Abamectin significantly upregulated the hepatic CYP-2E1 expression with excess generation of oxidative radicals, as evident by the significant depletion of reduced glutathione and elevation of malondialdehyde concentration (p ≤ 0.05) in rat liver and brain tissues. Further, ABM significantly increased TNF-α concentration, the expression of caspase-3 and p38 MAPK in the liver, as well as p-glycoprotein and GABA-A receptor in the brain. These results were in line with the observed histopathological changes. Sesame oil and/or AA supplementation alleviated ABM-induced cell damage by modulating all tested parameters. In conclusion, ABM induces oxidative stress and increases the expression of CYP-2E1, caspase-3, and p38 MAPK in the liver, as well as P-gp and GABA-A receptor in the brain. These effects could be ameliorated by SO and AA, alone and in combination, probably due to their anti-oxidant, anti-apoptotic, and gene-regulating activities.

The residue levels of spinosad and abamectin in eggs and tissues of laying hens following spray application

ABSTRACTSpinosad (SPN) and abamectin (ABM) are used in poultry premises to control external parasites including red mites (Dermanyssus gallinae). This study aimed to determine levels of SPN (spinosyn A + spinosyn D) and ABM residues in egg and edible tissues of laying hens following spray application. A total of 36 laying hens were divided into four groups of nine birds each, and they were kept in individual cages. Two different concentrations of SPN (2 and 4 g/l) and ABM (0.025 and 0.033 g/l) were applied in stocked and empty cages, respectively. Eggs were collected individually for 30 days. All hens were sacrificed at day 30 post–treatment, and tissue samples (liver, breast muscle, fat and skin) were collected. The residue levels in eggs and tissues were determined by high pressure liquid chromatography. ABM residues were not detectable in egg samples. SPN residues in eggs and residues of both ABM and SPN in liver, muscle and fat were under the maximum residue limits (MRLs) following low and high concentration applications. However, although the MRLs have not been established for SPN and ABM in skin tissue of chicken, residues in the skin detected at the low and high concentrations were greater than the MRLs for other edible tissues (except fat tissue) indicating that a withdrawal period would be necessary for the skin tissue after ABM and SPN use in laying hens.

Scientific support for preparing an EU position in the 51st Session of the Codex Committee on Pesticide Residues (CCPR).

In accordance with Article 43 of Regulation (EC) 396/2005, EFSA received a request from the European Commission to provide support for the preparation of the EU position for 51st session of the Codex Committee on Pesticide Residues (CCPR). In 2018, JMPR evaluated 15 active substances regarding the setting of toxicological reference values to be used in consumer risk assessment (chlorfenapyr, ethiprole, fenpicoxamid, fluazinam, fluxapyroxad, imazalil, kresoxim‐methyl, lambda‐cyhalothrin, mandestrobin, mandipropamid, norflurazon, pydiflumetofen, pyraclostrobin, pyriofenone, tioxazafen) and 27 active substances regarding the setting of maximum residue limits (MRLs) (abamectin, bentazone, chlorfenapyr, cyantraniliprole, cyazofamid, diquat, ethiprole, fenpicoxamid, fenpyroximate, fluazinam, fludioxonil, fluxapyroxad, imazalil, isofetamid, kresoxim‐methyl, lufenuron, mandipropamid, norflurazon, oxathiapiproline, profenofos, propamocarb, pydiflumetofen, pyraclostrobin, pyriofenone, pyriproxyfen, sulfoxaflor and tioxazafen); EFSA prepared comments on the Codex MRL proposals and the proposed toxicological reference values. In addition, EFSA provided comments on follow‐up assessments of JMPR on pesticides where specific concerns were raised in the previous CCPR meetings. The current report should serve as the basis for deriving the EU position for the CCPR meeting.

The potential for pesticide trunk injections for control of thousand cankers disease of walnut

Thousand cankers disease, caused by the pathogen Geosmithia morbida vectored by the bark beetle Pityophthorus juglandis , has emerged as an important disease of walnut trees in Europe. The present study was performed to evaluate the efficacy of trunk injections of four commercial fungicides and one insecticide for control of the fungus and its vector. Laboratory tests indicated that fungicides containing prochloraz + tetraconazole were the most effective. Field trials on non-infected trees allowed for the selection of a mixture containing prochloraz and tetraconazole (Binal Pro), the insecticide abamectin (Vertimec EC) and the adjuvant 2-(2-ethoxyethoxy) ethanol (Carbitol TM ) as having rapid host uptake. Injections of this formulation in naturally infected black walnut trees reduced the presence of G. morbida , supporting trunk injection as an efficient and low impact technique to manage fungal damage on infected trees.

Synthesis of succinic monoamide avermectin esters

Reaction of avermectin B1 hemisuccinate with N-hydroxysuccinimide and N,N’-dicyclohexylcarbodiimide followed by amination provided succinic monoamide avermectine esters that are potential antiparasitics.

Abamectin induces apoptosis and autophagy by inhibiting reactive oxygen species-mediated PI3K/AKT signaling in MGC803 cells.

Abamectin (ABA) is one of the most widely used compounds in agriculture and veterinary medicine. However, the cytotoxicity of ABA in human gastric cells is utterly unknown. In this study, ABA suppressed the proliferation of MGC803 cells by arresting the cell cycle at the G0/G1-phase. Moreover, ABA induced mitochondrial-mediated apoptosis by inducingthe loss of mitochondrial membrane potential, upregulationof Bax/Bcl-2, and activation of caspase-3. ABA significantly improved the LC3-II/LC3-I ratio and reduced P62 protein expression in a dose-dependent manner. Through detection of the reactive oxygen species (ROS) levels, we found ABA induced the accumulation of intracellular ROS and then reduced PI3K/AKT signaling activation relatedto MGC803 cellapoptosis and autophagy. Our results indicate that ABA exerts cytotoxic effects on human MGC803 cells through apoptosis and autophagy by inhibiting ROS-mediated PI3K/AKT signaling. Furthermore, ABA may be a potential risk to human gastric health.

Avermectin B1 5-O-mono-and 4″,5-O, O-bis-derivatization with ethyl succinoyl moiety

Reaction of avermectin B1 with succinic acid monoethyl ester chloride under catalysis of 2,6-lutidine provided hitherto unknown 5-O-mono- and 4″,5-O, O-bis-derivatives with ethyl succinoyl moiety that are potential antiparasitics.

Physiological traits of land snails Theba pisana as simple endpoints to assess the exposure to some pollutants.

In the current study, the toxicity bioassay of three pollutants abamectin (ABM), thiamethoxam (TMX), and acrylamide (ACR) against land snails Theba pisana was measured. Also, the ecotoxicological effects of dietary exposure to sublethal concentration (1/20 LC50) of these pollutants for 2-week exposure and 1-week recovery on some physiological endpoints evaluated as feeding activity, growth response, and carbonic anhydrase activity as a marker in charge of shell formation and seromucoid level as a marker in charge of mucus synthesis of the snails were studied. The results exhibited that the 48-h LC50 values were 0.91, 313.8, and 45.7 μg/g dry food for ABM, TMX, and ACR, respectively. The sublethal concentrations of these pollutants in the diet after 2-week exposure were found to reduce the food consumption and inhibit growth rate of the snails. Also, the data illustrated that carbonic anhydrase activity was significantly decreased. On the other hand, there was a significant increase in the seromucoid level as a marker responsible for mucus synthesis in ABM- and TMX-exposed snails, while ACR showed significantly decreased level when compared to control. After 1-week recovery, the tested endpoints of treated snails were slightly repaired but still less than that of the untreated animals. The overall outcome of this investigation suggests the utility of this animal as a good bioindicator organism for ABM, TMX, and ACR exposure in pollution monitoring studies.

Investigating the in vitro and in vivo nematicidal performance of structurally related macrolides against the root-knot nematode, Meloidogyne incognita

Summary Avermectins and spinosyns are structurally related natural products of microbial origin and belong to a new family of macrolides which are active against a vast array of invertebrate pests. In the present study, the effects of four members of macrolides; abamectin (ABM), emamectin benzoate (EMB), spinosad (SPI) and spinetoram (SPIT), on Meloidogyne incognita were investigated under in vitro and in vivo conditions. All compounds reduced egg hatching and led to high mortality of the nematode second-stage juveniles (J2). ABM showed the maximum rate of egg hatching inhibition and J2 mortality while SPIT recorded the minimum. All treatments reduced the number of galls, egg masses, eggs/egg mass in roots and J2 in the soil when compared to the control. Based on the 10 folds of the 24 h-LC50 values of J2 mortality in vitro, EMB and ABM exhibited higher percent reduction in galls (79.68 and 71.45%), egg masses (75.19 and 70.54%), eggs/egg mass (60.49 and 40.91%) and J2 in the soil (90.31 and 86.54%), respectively, compared to SPI and SPIT. Significant increase in tomato shoot height occurred in all biopesticides (10 folds) and SPIT (20 folds). SPI at 10 folds of the 24 h-LC50 values of J2 mortality in vitro, significantly increased root length while ABM at 50 folds and SPIT at 20 folds decreased root length by 5.15% and 5.88%, respectively, compared to the untreated inoculated plants. In all treatments, the dry shoot and root weights increased, compared to the untreated control. Our findings suggest that these macrolides have the ability to regulate nematode population densities and may be an alternative to classical nematicides.

Are bioinsecticides able to effectively substitute chemicals in the control of insect pests of okra (Abelmoschus esculentus L. Moench) in Cote d'Ivoire?

Objective: Okra (Abelmoschus esculentus, Malavaceae) production faces pest and disease attacks that leads to use of chemical pesticides. This study was performed to compare effectiveness of the bioinsecticide Levo 2.4 SL (Oxymatrin 2% and Prosular 0.4%) to the chemical pesticides Abalone 18 EC (Abamectin 18g/l) and Viper 46 EC (Acetamiprid 16g/l and Indoxacarb 30g/l) against okra insect pests in Cote d'Ivoire. Methodology and Results: So a field experiment was carried out at Bonoua (05°16'17N; 03°35'40 W) in the South East of Cote d’Ivoire, in a Randomized Complete Block Design (RCBD) with four replications and four treatments; Levo 2.4 SL, Abalone 18 EC, Viper 46 EC and the Control. Insect communities, damages and yield profit rate were assessed and analyzed with Statistica 7.1 at 5%. The inventory of insect allowed the identification of 28 species distributed into 19 families and 10 orders. The main pest insects observed were Hemiptera; Aphis gossypii (41.59%), Bemisia tabaci (39.11%), Jacobiasca sp (1.26%) and Dysdercus wolkerii (1.44%), Coleoptera; Podagrica decolorata (9.03%) and caterpillars of Lepidoptera; Syllepte derogate (1.36%). Then control plots presented no healthy plants (0%), while the bioinsecticide (Levo 2.4 SL), and the chemical insecticides; Abalone 18 EC and Viper 46 EC presented respectively 60%, 77.5% and 90% of healthy plants (index 0). Overall, the effectiveness of the bioinsecticide to control insect pests appeared similar to those of the chemical pesticides. However, Levo 2.4 SL seems to be less effective against Aphis gossypii and Dysdercus wolkerii populations. Highest fruit yield of okra was recorded in treated plot with Viper 46 EC (12.55±0.98 t/ha), followed by Abalone 18 EC (12.2±0.8 t/ha) and Levo 2.4 SL (11.15±1.09 t/ha). Whereas, the lowest yield obtained from control plots was 6.84±0.15 t/ha. The yield profit rates were 62.82; 78.18 and 83.28% respectively for Levo 2.4 SL, Abalone 18 EC and Viper 46 EC when compared to the control. The control of insect pests by the bioinsecticide and the chemical insecticides increased significantly the okra yield. Conclusion and application of Results: Therefore, the bioinsecticide can be eco-friendly alternative to control insect pest of okra in Cote d’Ivoire. Then, the bioinsecticide Levo 2.4 SL can be proposed to limit damages caused by chemicals on the environment and human health.Keywords: Bioinsecticide, Levo 2.4 SL, Abelmoschus esculentus, insect pests, Cote d’Ivoire.

Assessment of the long-acting ivermectin formulation in sheep: Further insight into potential pharmacokinetic interactions.

The aim of the current study was to evaluate the in vivo pharmacokinetic of ivermectin (IVM) after the administration of a long-acting (LA) formulation to sheep and its impact on potential drug-drug interactions. The work included the evaluation of the comparative plasma profiles of IVM administered at a single therapeutic dose (200μg/kg) and as LA formulation at 630μg/kg. Additionally, IVM was measured in different gastrointestinal tissues at 15days posttreatment with both IVM formulations. The impact of the long-lasting and enhanced IVM exposure on the disposition kinetics of abamectin (ABM) was also assessed. Plasma (IVM and ABM) and gastrointestinal (IVM) concentrations were analyzed by HPLC with fluorescent detection. In plasma, the calculated Cmax and AUC0-t values of the IVM-LA formulation were 1.47- and 3.35-fold higher compared with IVM 1% formulation, respectively. The T1/2ab and Tmax collected after administration of the LA formulation were 2- and 3.5-fold longer than those observed after administration of IVM 1% formulation, respectively. Significantly higher IVM concentrations were measured in the intestine mucosal tissues and luminal contents with the LA formulation, and in the liver, the increase was 7-fold higher than conventional formulation. There was no drug interaction between IVM and ABM after the single administration of ABM at 15days post-administration of the IVM LA formulation. The characterization of the kinetic behavior of the LA formulation to sheep and its potential influence on drug-drug interactions is a further contribution to the field.

Insecticidal efficacy of abamectin against red flour beetle Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae): influence of dose, exposure interval, relative humidity and temperature: Poster

Insecticidal efficacy of abamectin against red flour beetle Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae): influence of dose, exposure interval, relative humidity and temperature: Poster

Use of multiple endpoints to investigate the ecotoxicological effects of abamectin and thiamethoxam on Theba pisana snails

The ecotoxicological effects of dietary exposure to sublethal concentration (1/20 LC50) of abamectin (ABM) and thiamethoxam (TMX) for two weeks exposure and one week recovery on oxidative stress parameters; lipid peroxidation (LPO), reduced glutathione (GSH), catalase (CAT) and glutathione S-transferase (GST), Deoxyribonucleic acid (DNA) damage as well as immunological parameters; cell death, phagocytosis, lysosomal membrane stability (LMS), lectins, superoxide anion (O2-) generation, phenoloxidase (PO), peroxidase (POD) and hemocyanin (Hc) of the land snail, Theba pisana were examined. The results showed that both tested compounds significantly increased DNA damage, LPO content, the activity of CAT and GST, cell death, POD activity, Hc level, whereas, significantly declined in phagocytic activity, LMS, lectins level, O2– generation, PO activity, and GSH content compared to the controls after two week exposure. After one week of recovery, the measured biochemical parameters of treated snails were slightly repaired but their levels were still less than that of the level of untreated animals. Overall, based on acute toxicity endpoints, ABM appeared to be more harmful than TMX against this animal. Indeed, the different patterns of endpoint responses could represent a useful picture to characterise exposure to these pesticides in the land snail, T. pisana. This battery of snail endpoints might be a promising option to biomonitor the health of the terrestrial ecosystem and to offer valuable insights to the pesticides toxicity mechanisms.

Effect of soil fumigants on degradation of abamectin and their combination synergistic effect to root-knot nematode.

BackgroundRoot-knot nematode (Meloidogyne spp., RKN) causes a disease that significantly reduces the yield of greenhouse cucumber crops year after year. Chemical control based on a single pesticide is now unreliable mainly due to pest resistance. Fumigant and non-fumigant pesticide combinations can potentially result in effective and economic RKN control.ResultsCombining the insecticide abamectin (ABM) with fumigants dazomet (DZ) or chloropicrin (CP) significantly extended the half-life of ABM by an average of about 1.68 and 1.56 times respectively in laboratory trials, and by an average of about 2.02 and 1.69 times respectively in greenhouse trials. Laboratory experiments indicated that all the low rate ABM combination treatments controlled RKN through a synergistic effect. ABM diffused into the nematode epidermis more rapidly when ABM was combined with DZ and CP, giving effective nematode control and an increase cucumber total yield, compared to the use of these products alone. ABM combined with CP or DZ produced significantly higher total cucumber yield than when these products were used alone.ConclusionsA low concentration of ABM combined with DZ in preference to CP would be an economic and practical way to control nematode and soilborne fungi in a greenhouse producing cucumbers.