Removal of fenamiphos, imidacloprid, and oxamyl pesticides from water by microalgal Nannochloropsis oculata biomass and their determination by validated HPLC method.

The present study assessed the removal of fenamiphos, imidacloprid, and oxamyl pesticides from water using algal Nannochloropsis oculata biomass. Several factors, such as algal biomass concentration, incubation time, and pesticide concentration, were studied for their impact on pesticide removal. Analysis and quantification of pesticides by rapid HPLC have been developed and validated. The optimum conditions were obtained at 15 min, 50 mg/L of pesticide concentration, and 4,500 mg/L of the algal biomass with 92.24% and 90.43% removal for fenamiphos and imidacloprid, respectively. While optimum parameters of 10 min incubation, 250 mg/L of pesticide concentration, and 2,750 mg/L of the algal biomass exhibited 67.34% removal for oxamyl. N. oculata, marine microalgae, successively removed different concentrations of the tested pesticides from water, and the algal biomass showed a potential reduction of pesticides in polluted water samples.

Molecularly imprinted polymer film loaded on the metal-organic framework with improved performance using stabilized gold-doped graphite carbon nitride nanosheets for the single-step detection of Fenamiphos.

A noninvasive material-based electrochemical sensor continuously monitors the fenamiphos (FMS) level in vegetable samples is highly desirable for innovative fabrics to check the health of agricultural products. Herein, an electrochemical sensor is fabricated by a sensitive molecularly imprinted polymers/metal-organic framework/gold stabilized on graphite carbon nitride (MIP-Au@MOF-235@g-C3N4) for monitoring the FMS level in real samples continuously with high sensitivity and accuracy. The MIP-based sensor was simply produced by a hydrothermal strategy. The MIP-Au@MOF-235@g-C3N4 had a large specific surface area and high catalytic activity, which enables the fabricated sensor with good electrochemical performance with a high sensitivity of 1.07 µA.µM-1 and a wide linear range of 0.01 to 16.4 µM. The proposed strategy was applied to determine FMS in agricultural products with satisfactory recoveries (94.7-107.9%) and a relative standard error of less than 1.0%, providing novel tactics for the rational design ofMIP-sensorsto determine a growing number of deleterious substances.

A highly sensitive fluorescent sensor for fenamiphos detection in vegetable samples and living cells based-on an enzyme free system.

Fenamiphos (Fena), an organophosphorous pesticide, is widely used in agricultural soils to control nematodes and thrips. This nematicide is harmful to fish, birds and humans and, causes several diseases. Therefore, the determination of the nematicide is crucial. Fena has been generally detected by enzyme-based systems which require specific conditions. Herein, we integrated a xanthene moiety and a pyrimidine moiety to obtain an enzyme-free detection system for Fena and, a fluorescent sensor (N-(6-(diethylamino)-9-(pyrimidin-5-yl)-3H-xanthen-3-ylidene)-N-ethylethanaminium hexafluorophosphate(V)) (RosPm) was easily prepared. The colorimetric and spectroscopic properties of RosPm were investigated using the UV-vis and fluorescence spectroscopy. RosPm exhibited a high selectivity and sensitivity to Fena over all the metal ions, the anions and pesticides tested in acetonitrile (ACN)/water (H2O) (v:v, 1:1) solution. RosPm showed a clear visual change from purple to light-purple resulting fluorescent quenching with Fena. This sensor could be preferred for detecting Fena in vegetable samples such as tomato, pepper, and cucumber, and visualizing Fena in living MFC-7 cells.

A novel detection method for organophosphorus insecticide fenamiphos: Molecularly imprinted electrochemical sensor based on core-shell Co3O4@MOF-74 nanocomposite.

Organophosphorus insecticide fenamiphos (FEN) is utilized to control the detrimental nematode pests. In this report, a novel molecular imprinted electrochemical sensor for insecticide FEN detection was prepared. The molecular imprinted sensor was prepared based on Co3O4 nanowire and core-shell Co3O4@MOF-74 nanocomposite. Firstly, hydrothermal method followed by thermal annealing was applied for the preparation of Co3O4 nanowire. Then, solvothermal technique was used in no presence of metal salts to prepare core-shell Co3O4@MOF-74 nanocomposite. In addition, several solvothermal cycles were tried to optimally adjust the reaction efficiency. After the modification of the clean carbon electrode surfaces with Co3O4@MOF-74 nanocomposites, the molecular imprinted electrodes based on Co3O4@MOF-74 nanocomposites were prepared in presence of 100.0 mM pyrrole as monomer and 25.0 mM FEN as analyte molecule between +0.30 V and +1.50 V by cyclic voltammetry (CV). The prepared molecularly imprinted sensor based on Co3O4 nanowire and core-shell Co3O4@MOF-74 nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and CV. The quantification limit (LOQ) and the detection limit (LOD) were obtained as 1.0 × 10-11 M and 3.0 × 10-12 M, respectively, by using the developed sensor. Hence, the developed molecularly imprinting electrochemical sensor having high selectivity, stability and reproducibility was presented in this study for insecticide FEN detection.

Facile extraction and determination of organophosphorus pesticides in vegetables via magnetic functionalized covalent organic framework nanocomposites.

Facile enrichment and determination of trace organophosphorus pesticides (OPPs) in foods has been a constantly pursuing goal in food safety field. Herein, Zr4+-immobilized covalent organic frameworks (Fe3O4@COF@Zr4+) have been first constructed and utilized as the powerful adsorbents for magnetic solid-phase extraction (MSPE) of OPPs. Owing to the π-π stacking interaction, hydrogen bonding and Zr4+-phosphate coordination reaction, the composites exhibited excellent selectivity and superior affinity to OPPs. Under optimized conditions, the proposed MSPE method coupled with GC-FPD showed good linearity (R2 ≥ 0.9990) and yielded low limits of detection (0.7-3.0 µg kg-1) for OPPs. Moreover, the developed method was successfully employed for the quantitation of OPPs in spiked vegetable samples and obtained satisfactory recoveries in the range of 87-121% with the relative standard deviations (RSDs) ≤ 8.9%. These results demonstrated that the prepared nanoparticles hold unique advantages for trace OPPs analysis in foodstuffs.

Risk assessment of the chiral pesticide fenamiphos in a human model: Cytochrome P450 phenotyping and inhibition studies.

Fenamiphos (FS) is a chiral organophosphate pesticide that is used to control nematodes in several crops. Enantioselective differences may be observed in FS activity, bioaccumulation, metabolism, and toxicity. Humans may be exposed to FS through occupational and chronic (food, water, and environmental) exposure. FS may cause undesirable CYP450 pesticide-drug interactions, which may impact human health. Here, the CYP450 isoforms involved in enantioselective FS metabolism were identified, and CYP450 inhibition by rac-FS, (+)-FS, and (-)-FS was evaluated to obtain reliable information on enantioselective FS risk assessment in humans. CYP3A4 and CYP2E1 metabolized FS enantiomers, and CYP2B6 may participate in rac-FS metabolism. In addition, rac-FS, (+)-FS, and (-)-FS were reversible competitive CYP1A2, CYP2C19, and CYP3A4/5 inhibitors. High stereoselective inhibition potential was verified; rac-FS and (-)-FS strongly inhibited and (+)-FS moderately inhibited CYP1A2. Stereoselective differences were also detected for CYP2C19 and CYP3A4/5, which were strongly inhibited by rac-FS, (+)-FS, and (-)-FS. Our results indicated a high potential for CYP450 drug-pesticide interactions, which may affect human health. The lack of stereoselective research on the effect of chiral pesticides on the activity of CYP450 isoforms highlights the importance of assessing the risks of such pesticides in humans.

Response of Tomato Rhizosphere Bacteria to Root-Knot Nematodes, Fenamiphos and Sampling Time Shows Differential Effects on Low Level Taxa.

A factorial taxonomic metabarcoding study was carried out to determine the effect of root-knot nematodes (Meloidogyne incognita, RKN) and the nematocide fenamiphos on the rhizosphere microbiome of tomato. Plants inoculated (or not) with RKN second-stage juveniles (J2), and treated (or not) with the nematocide, were tested in a 6 months greenhouse assay using a RKN-free soil proceeding from an organic crop. Rhizosphere soil was sampled at J2 inoculation, 3 months later (before the second nematocidal treatment), and again after 3 months. At each sampling, the RNAs were extracted and the 16S rRNA V4 regions sequenced with a Next Generation Sequencing (NGS) protocol. Changes in bacteria metagenomic profiles showed an effect of the treatments applied, with different representations of taxa in samples receiving nematodes and fenamiphos, at the two sampling times. In general, a tendence was observed toward an increase number of OTUs at 6 months, in all treatments. ß-Proteobacteria were the most abundant class, for all treatments and times. When compared to soil before transplanting, the presence of tomato roots increased frequency of Actinobacteria and Thermoleophilia, reducing abundance of Solibacteres. At lowest taxonomic levels the samples clustered in groups congruent with the treatments applied, with OTUs differentially represented in relation to RKN and/or fenamiphos applications. Bacillus, Corynebacterium, Streptococcus, and Staphylococcus were more represented at 6 months in samples inoculated with RKN. The nematodes with the nematocide application increased the emergence of rare OTUs or reduced/enhanced the abundance of other taxa, from different lineages.

Purification and characterization of a novel fenamiphos hydrolysing enzyme from Microbacterium esteraromaticum MM1.

Fenamiphos is a neurotoxic organophosphorus pesticide used widely to control pests of crops. Fenamiphos and its toxic oxidation products have been detected in surface and groundwaters. A novel enzyme capable of hydrolysing P-O-C bond of fenamiphos is purified from Microbacterium esteraromaticum MM1 total cellular protein using a combination of methods. The purified fenamiphos hydrolysing enzyme (FHE) was identified as enolase (phosphopyruvate hydratase), a housekeeping enzyme with molecular mass and pI value of 45 kDa and 4.5, respectively. The optimum pH and temperature for the activity of the FHE are 7 and 25 °C, respectively. We studied the influence of metal ions and inhibitors on the enzyme activity. The enzyme was strongly activated by Mg2+ whereas Hg2+ and phenylmethyl sulfonyl fluoride (PMSF) inhibited the enzyme. The kinetic parameters, Km and Vmax for fenamiphos hydrolysis were estimated to be 584.15 ± 16.22 µM and 6.46 ± 0.13 µM min-1, respectively. The FHE was functionally active against its original substrate (2-phosphoglycerate) with Km value of 5.82 ± 1.42 µM and Vmax of 4.2 ± 0.1 µM min-1. This enzyme has great potential for its application in the detoxification of fenamiphos and its warfare homologs. To our knowledge, this is the first report on the purification of fenamiphos hydrolysing enzyme.

Photoelectrocatalyzed degradation of organophosphorus pesticide fenamiphos using WO3 nanorods as photoanode.

In this study, WO3 nanostructures were synthesized by the electrochemical anodization technique to use them on the degradation of persistent organic compounds such as the pesticide fenamiphos. The acids electrolyte used during the anodization were two different: 1.5 M H2SO4 - 0.05 M H2O2 and 1.5 M CH4O3S - 0.05 M H2O2. Once the samples have been manufactured, they have been subjected to different tests to analyze the properties of the nanostructures. With Field Emission Scanning Electron Microscopy (FE-SEM) the samples have been examined morphologically, their composition and crystallinity has been studied through Raman Spectroscopy and their photoelectrochemical behaviour by Photoelectrochemical Impedance Spectroscopy (PEIS). Finally, degradation tests have been carried out using the technique known as photoelectrocatalysis (PEC). The conditions that were applied in this technique were a potential of 1 VAg/AgCl and simulated solar illumination. The degradation process was monitored by UV-Visible and High-Performance liquid Chromatography (HPLC) to control the course of the experiment. The nanostructures obtained with 1.5 M CH4O3S - 0.05 M H2O2 electrolyte showed a better photoelectrochemical behaviour than nanostructures synthesized with 1.5 M H2SO4 - 0.05 M H2O2. The fenamiphos degradation was achieved at 2 h of experiment and the intermediate formation was noticed at 1 h of PEC experiment.

Peer review of the pesticide risk assessment of the active substance fenamiphos.

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State Greece and co-rapporteur Member State Cyprus for the pesticide active substance fenamiphos are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of fenamiphos as a nematicide in fruiting vegetables (i.e. tomato, aubergine, cucumber, pepper and courgette), herbaceous ornamentals and in nursery stock (both perennial and herbaceous species). The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

Sorption and mobility of 14C-fenamiphos in Brazilian soils.

Although fenamiphos is widely used as an insecticide and nematicide in bowling greens and agriculture, information on its sorption in tropical soils is limited. In this study, mobility, sorption, and desorption dynamics of 14C-fenamiphos in three contrasting Brazilian soils were examined both in batch and column experiments. Fenamiphos sorption coefficients (K d ) were 2.33, 3.86, and 3.9 L kg-1 for the three soils tested. The insecticide exhibited linear adsorption isotherms in all the three soils, and desorption was in a range of 30-40% during a 72-h period. With its low mobility, fenamiphos did not percolate through the soil profile even after 48 h. However, there is a risk of leaching to water bodies due to runoff because of its high solubility in water. In view of the fact that fenamiphos and its oxidation products are highly toxic to aquatic invertebrates and could affect the soil microbial activities even at low concentrations, the present information is of great importance in risk assessment of fenamiphos in the environment.

Biochemical interactions between Glycine max L. silicon dioxide (SiO2) and plant growth-promoting bacteria (PGPR) for improving phytoremediation of soil contaminated with fenamiphos and its degradation products.

Fenamiphos is a systematic nematicide-insecticide used extensively for the control of soil nematodes. Fenamiphos and oxidation products have been known to induce water pollution, soil pollution and ecotoxicological effects on aquatic organisms, as well as heath issues. This contaminant can be removed by phytoremediation. Herein, we tested several strategies to improve the effectiveness of this technology. A combination of G. max plus Pseudomonas fluorescens was more efficient than G. max plus Serratia marcescens or G. max alone in degrading fenamiphos to other metabolites. Three major metabolites, namely fenamiphos sulfoxide (FSO), fenamiphos sulfone (FSO2) and fenamiphos phenol (F-phenol), were detected in roots and leaves in which G. max amended with P. fluorescens or amended with S. marcescens produced a significant accumulation of FSO and FSO2 with higher amounts than for G. max alone. Leaf concentrations of FSO were always higher than in the roots, while FSO2 accumulated significantly more in G. max roots than in G. max leaves. In soil treated with fenamiphos, G. max roots and leaves alone, and in combined effects of plant and microorganisms, resulted in the disappearance of fenamiphos and the appearance of F-SO, F-SO2 and F-phenol, which in turn caused toxic stress in G. max and the resulting production of reactive oxygen species such as H2O2 with higher content and an increase in antioxidant GPX activity. Although a batch equilibrium technique showed that use of SiO2 resulted in the efficient removal of fenamiphos when compared with other treatments for removing adsorbed fenamiphos from soil, a fewer amount of fenamiphos was removed by G. max L. with SiO2. H2O2 content and GPX activity increased in G. max under fenamiphos treatment and its degradation products, while amended G. max with SiO2 or Argal led to a decrease in GPX activity and H2O2 content.

Comparative efficacy of different approaches to managing Meloidogyne incognita on green bean.

A greenhouse study was conducted to compare the relative efficacy of different approaches to managing Meloidogyne incognita on green bean. These approaches included chemical (fumigant, non-fumigant, seed dressing, and seed dip), biological (the egg-parasitic fungus, Paecilomyces lilacinus and the mycorrhizal fungus Glomus sp.), physical (soil solarization), and cultural (chicken litter and urea) methods. Accordingly, nine different control materials and application methods plus nematode-infected and non-infected controls were compared. Two important parameters were considered: plant response (plant growth and root galling) and nematode reproduction (production of eggs and the reproduction factor Rf). The results showed that the use of chicken litter as an organic fertilizer severely affected the growth and survival of the plants. Therefore, this treatment was removed from the evaluation test. All of the other eight treatments were found to be effective against nematode reproduction, but with different levels of efficacy. The eight treatments decreased (38.9-99.8%) root galling, increased plant growth and suppressed nematode reproduction. Based on three important criteria, namely, gall index (GI), egg mass index (EMI), and nematode reproduction factor (RF), the tested materials and methods were categorized into three groups according to their relative control efficacy under the applied test conditions. The three groups were as follows: (1) the relatively high effective group (GI = 1.0-1.4, Rf = 0.07-0.01), which included the fumigant dazomet, the non-fumigant fenamiphos, soil solarization, and seed dip with fenamiphos; (2) the relatively moderate effective group (GI = 3.4-4.0, Rf = 0.24-0.60), which included seed dressing with fenamiphos and urea; and (3) the relatively less effective group (GI = 5.0, Rf = 32.2-37.2), which included P. lilacinus and Glomus sp.

Effect of urea and certain NPK fertilizers on the cereal cyst nematode (Heterodera avenae) on wheat.

Two outdoor pot experiments were conducted in two consecutive years under outdoor conditions during the wheat growing season in Saudi Arabia to determine the effects of urea and certain compound fertilizers (NPK), compared to the effects of the nematicide fenamiphos on the cereal cyst nematode (CCN), Heterodera avenae, and wheat growth. The results showed that all of the treatments, except the fertilizer diammonium phosphate (DAP), reduced the number of nematode cysts/root system and increased (P â©½ 0.05) the dry weight of nematode-infected wheat plants. Fenamiphos and urea resulted in the best control, followed by the NPK fertilizers. The combined application of urea and fenamiphos resulted in the most significant effect in decreasing (P â©½ 0.05) the number of cysts/root system and increasing (P â©½ 0.05) the growth of nematode-infected wheat plants.

Nematicidal activity of fluensulfone against some migratory nematodes under laboratory conditions.

BACKGROUND: The fluoroalkenyl fluensulfone, known to have strong nematicidal activity against Meloidogyne spp. (root-knot nematodes), was evaluated in vitro and in soil against the migratory nematodes Bursaphelenchus xylophilus, Aphelenchoides besseyi, Aphelenchoides fragariae, Ditylenchus dipsaci, Pratylenchus penetrans, Pratylenchus thornei and Xiphinema index. RESULTS: B. xylophilus and D. dipsaci were not immobilised by 48 h in vitro exposure to up to 16 mg L(-1) of fluensulfone. A. besseyi and A. fragariae were affected by 8 mg L(-1) , the highest concentration used for these nematodes. More than 60% of P. penetrans and P. thornei were immobilised by 4 mg L(-1) of fluensulfone; however, exposure of P. penetrans to the compound prior to inoculation did not affect their root penetration ability. The immobilisation rate of X. index was increased by 48 h exposure to even 1.0 mg L(-1) of fluensulfone. Incorporation of over 2 mg L(-1) of fluensulfone into the soil reduced populations of P. penetrans and P. thornei before and after planting lettuce and chickpea respectively. The efficacy of fluensulfone against the tested nematodes was the same or higher than that of fenamiphos in most cases. CONCLUSION: A. besseyi, A. fragariae, B. xylophilus and D. dipsaci were tolerant to fluensulfone and fenamiphos. P. penetrans, P. thornei and X. index were affected by fluensulfone, but nematicidal activity was much lower than that reported for root-knot nematodes.

Effects of a Resistant Corn Hybrid and Fenamiphos on Meloidogyne incognita in a Corn-Squash Rotation.

The efficacy of a double-cross corn (Zea mays) hybrid (Old Raccoon selection X T216) X (Tebeau selection X Mp 307) resistant to Meloidogyne incognita as a rotational crop, and fenamiphos treatment for management of root-knot nematode (M. incognita race 1) in squash (Cucurbita pepo var. melopepo) was evaluated in field tests during 1996 and 1997. Numbers of M. incognita in the soil and root-gall indices were lower on the resistant hybrid than on a commercial cultivar DeKalb DK-683. Treatment means across both corn entries had lower root-gall indices following fenamiphos treatment. In soil collected 2 September 1997, there were more colony-forming units (cfu) per gram of oven-dried soil of Pythium spp. from plots planted to DK-683 treated with fenamiphos than in untreated plots (88 vs. 59 cfu). Some corn plots had individual plants with 10% to 15% of the crown and brace roots decayed, but no differences due to fenamiphos treatment. Lodging of stalks was 40% to 50% more in the double-cross hybrid than in DK-683. Yield was greater from DK-683 than the double-cross hybrid. Based on cultivar means across fenamiphos treatments and fenamiphos treatment means across cultivars, root-gall indices and yield of squash were significantly lower following the double cross hybrid than DK-683 and in fenamiphos-treated plots than in untreated plots of squash. Yield of squash was not affected by at-planting treatment with fenamiphos on the preceding crops of corn. Nematode resistance must be transferred into the elite materials of commercial seed companies to reach its full potential as a nematode management strategy.

Fosthiazate Controls Meloidogyne arenaria and M. incognita in Flue-Cured Tobacco.

The nematicide fosthiazate was evaluated over a 3-year period for management of Meloidogyne incognita race 3 (site 1) and M. arenaria race 2 (site 2) in flue-cured tobacco. Fosthiazate was applied broadcast and incorporated at rates ranging from 22 to 88 g a.i./100 m(2), and compared with the nematicides fenamiphos (67 g a.i./100 m(2)), 1,3-D (56.1 L/ha, 670 ml/100-m row), and an untreated control. Root-gall indices and leaf yields were averaged over the 3-year period. Root galling was negatively correlated in a linear relationship with fosthiazate application rate at sites 1 and 2. Leaf yields were positively correlated with fosthiazate application rate at site 1 and could be described by a quadratic equation. Leaf yields were greater at 33 and 88 g a.i./100 m(2) application rates (site 2) than the untreated control. Leaf yields in fosthiazate (88 g a.i./100 m(2))-treated plots infested with M. incognita or M. arenaria were not different from plots fumigated with 1,3-D. Plants in plots with fosthiazate applied in a row band (1993) had a lower root-gall index than those in plots with the same rate of fosthiazate applied broadcast. Fosthiazate may provide an alternative to fumigation for control of M. incognita and M. arenaria.

Degradation of fenamiphos in agricultural production soil.

Nematicides are used to control a wide variety of nematodes on many crops; unfortunately, oftentimes the control they provide is erratic. This erratic behavior is not always predictable and has been associated with chemical, physical, and biological degradation of nematicides. Their accelerated degradation is an agricultural problem that has been observed in crop monocultures and in other crop production systems where a biodegradable compound is repeatedly applied to the same soil. The problem can occur in field soil and golf course greens; it is not unique to any single nematicide or class of nematicides, but rather to many classes of pesticides. As indicated by the population density of root-knot nematodes (Meloidogyne incognita) in the soil in a 6-year sweet corn-sweet potato-vetch rotation, the efficacy of the nematicide fenamiphos diminished during the third year. Therefore, use of the nematicide applied immediately before planting sweet corn, sweet potato, and vetch should not exceed 3 years. After 3 years, the crop rotation and(or) the nematicide should be changed.

Crop yields and nematode population densities in triticale-cotton and triticale-soybean rotations.

Triticale cv. Beagle 82, cotton cv. McNair 235, and soybean cv. Twiggs were arranged in three cropping sequences to determine the effects of fenamiphos and cropping sequence on nematode population densities and crop yields under conservation tillage for 4 years. The cropping sequences were triticale (T)-cotton (C)-T-C, T-soybean (S)-T-S, and T-C-T-S. Numbers of Meloidogyne incognita second-stage juveniles declined on trificale but increased on cotton and soybean each year. Root-gall indices of cotton and soybean ranged from 1.00 to 1.08 (1 to 5 scale: 1 = 0%, 2 = 1% to 25%, 3 = 26% to 50%, 4 = 51% to 75%, and 5 = 76% to 100% of roots galled) each year and were not affected by fenamiphos treatment or cropping sequence. Numbers of Pratylenchus brachyurus were maintained on trificale and generally increased more on soybean than on cotton. Population densities of Helicotylenchus dihystera were near or below detection levels in all plots during the first year and increased thereafter in untreated plots in the T-C-T-C and T-S-T-S sequences. Generally, yields of triticale in all cropping sequences declined over the years. Yields of cotton and soybean were not affected by fenamiphos at 6.7 kg a.i./ha. Cotton and soybean were grown successfully with little or no suppression in yields caused by nematodes in conservation tillage following triticale harvested for grain.

Curative and Residual Efficacy of Injection Applications of Avermectins for Control of Plant-parasitic Nematodes on Banana.

Studies were conducted to determine the curative and residual efficacy of avermectins at controlling plant-parasitic nematodes when injected into the pseudostem of banana, Musa acuminata cv. Cavendish. In addition, we determined the lowest concentration of avermectins that provided satisfactory efficacy as protectants when injected into banana pseudostems. Experiments were conducted with a root-knot nematode, Meleidogyne javanica, and the burrowing nematode, Radopholus similis. Injections (1 ml) of >/= 100 mug a.i./plant of abamectin into pseudostems were effective at controlling M. javanica and R. similis, and were comparable to control achieved with a conventional chemical nemaficide, fenamiphos, in a protectant assay. Abamecfin injections of 250 and 500 mug a.i./plant were effective at reducing nematode infections 28 to 56 days after inoculation. Abamectin was more effective than ivermectin at controlling nematodes after nematode populations were established in banana roots. Injections of between 100 and 1,000 mug a.i./plant were effective at controlling nematodes for at least 56 days after treatment. These studies confirmed earlier results and demonstrated that abamecfin has potential for controlling nematode parasites on banana when injected into the pseudostem.