Testing aldicarb as a bird repellent in a sprouting sugar beet field

Temik, the granular formulation of aldicarb [2-methyl-2(methylthio) propionaldehyde 0-(methylcarbamoyl) oxime], was placed together with sugar beet seeds during sowing along the rows, at a rate of 1.4 g/m, in a 1.5-ha experimental area within a 6-ha sugar beet field in an arid area with a long history of bird damage. Thirty-three chukar partridges, a major pest of sprouting crops, were observed foraging in the experimental area throughout the 4-week period between sowing and assessment of damage. Damage was restricted to the borders of the field, with a significant difference in level of damage between treated and control plots located along the borders; the size of damaged areas was about five times smaller in the treated plots than in the control plots. The results were interpreted as reflecting the repellent effect of aldicarb absorbed by the sprouts, and as establishment of a conditioned aversion by the chukars to sugar beet sprouts. The high toxicity of the treated sprouts was demonstrated when adult Japanese quail were fed sprouts collected from treated plots.     

Aldicarb sulfoxidation by plant root extracts

Soybean root homogenates were found to oxidize aldicarb to aldicarb sulfoxide. Fractionation of soybean root homogenate indicates that the enzyme(s) which oxidize aldicarb to the sulfoxide are largely (63%) in the 25,000g supernatant. In vitro studies of the 25,000g supernatant showed a linear reaction rate at 24 and 34°C for periods of up to 2 and 1 hr, respectively, at the pH optimum of 5.5. Bean and soybean root 25,000g supernatants were the most active on a per milligram of protein basis followed by corn, sorghum, barley, and tomato (8–27 nmol/mg of protein/hr). A 140-fold purification of soybean root aldicarb sulfoxidase was achieved. In vitro studies indicated that methomyl, methiocarb, phorate, Counter, fensulfothion, fenthion, Nemacur, EPTC, vernolate, carboxin, dl-methionine, l-cysteine, l-methionyl-l-serine, thiodiglycolic acid, lipoic acid, thiourea, and thioacetic acid when present at a 10:1 ratio with aldicarb significantly inhibited soybean root aldicarb sulfoxidation.     

The effect of high-level bird-repellent treatment with aldicarb on the germination and development of sugar beets

The effect of high-level treatment with aldicarb on sugar beet seed germination and on sprout growth rate was tested. Ten to 20 mg of Temik 10% granules (1–2 mg aldicarb) per seed was found to be the most appropriate. Due to the slow movement of aldicarb in soils, its absorbance rate from loess soil was found to be highly dependent on the distance between the granules and seeds.     

The effect of different ways of watering pots after the application of aldicarb on control of the potato cyst-nematode

The multiplication ofHeterodera rostochiensis on potatoes in pots was reduced more strongly by aldicarb mixed with the soil than by aldicarb applied to the top of the soil. Excessive amounts of water strongly reduced the effectiveness of the first method of application; moderate amounts of water did not improve the second method sufficiently.     

Residues of aldicarb in coconut

Determinations were made of aldicarb residues in coconut cultivated on soils containing aldicarb granules. The quantitative estimations in coconut milk and kernel were made by colorimetry and gas-liquid chromatography; samples harvested at various times were analysed. Residues in samples of kernel did not exceed 0.04 mg kg^?1 (total toxic aldicarb residues), while milk samples showed no detectable residues.     

Distribution of the radioactivity in sugar beet plants treated with [14C]aldicarb

Sugar beet plants were grown in the field, after in-furrow application of [¹⁴C]aldicarb (3 kg of aldicarb ha^?1) at planting. Some plants (the growing plants) were harvested 99 days after sowing and the rest (the ripe plants) 196 days after sowing. The percentages of the weights of [¹⁴C]aldicarb equivalents (the total aldicarb plus aldicarb sulphoxide and sulphone, plus all the other metabolites of [¹⁴C]aldicarb which contain ¹⁴C, expressed as aldicarb equivalents) incorporated into the beet plants, relative to the weight applied to the soil, were 2.8 and 1.8, respectively for the growing and ripe plants. The concentrations of [¹⁴C]aldicarb equivalents (mg kg^?1 fresh weight) in the growing and ripe plants, respectively were: blades of the external leaves, 3.16 and 0.93; blades of the internal leaves, 0.63 and 0.68; petioles of the external leaves, 0.51 and 0.26; petioles of the internal leaves, 0.15 and 0.05; crowns, 0.14 and 0.15; roots, 0.16 and 0.13. The proportions of the extractable aldicarb plus aldicarb sulphoxide and aldicarb sulphone determined by gas-liquid chromatography (expressed as aldicarb equivalents) relative to [¹⁴C]aldicarb equivalents, in the external and internal leaf blades of the growing beets, were 56 and 60%, respectively; these values declined to 25 and 19%, respectively in the ripe plants. The proportion was 21 % or less in all other parts of the growing and ripe plants.     

Antagonism of Azotobacter chroococcum isolates to Rhizoctonia solani

Antagonism of isolates ofAzotobacter chroococcum toRhizoctonia solani on agar plates was studied, and isolates were tested for their ability to controlR. solani infection of potato sprouts in sterilized and unsterilized soil. The degree of antagonism exhibited varied strongly among the isolates and was also found to be temperature-dependent. At 25, 20 and 15°C, all but one strongly antagonisticAzobacter isolate effectively prevented infection of sprouts of potatoes planted in a soil heavily infected with a pathogenic isolate ofR. solani. At 10°C none was effective.     

Evaluating insecticides for the control of narcissus flies under field conditions in Israel

In Israel, narcissus bulb flies (Diptera: Syrphidae) are serious pests of cultivated flower bulbs of the families Liliaceae and Amaryllidaceae. The large narcissus fly(Merodon eques) is the major pest, whereas the small narcissus fly (a new species in the genusEumerus, yet to be described) is only a secondary pest. The large narcissus fly is also considered a quarantine pest by the U.S.A. authorities. Narcissus bulbs,Narcissus tazetta (var. ‘Ziva’), were planted in an experimental field at Bizzaron during November 1995 and harvested during June 1996. Currently aldicarb (Temik) is recommended for the control of narcissus fly larvae. We compared the control efficacy of imidacloprid (Confidor) and isazofos (Miral) with that of aldicarb. These latter insecticides were applied to the soil in February, in April, or on both dates. The mean level of damaged bulbs in the untreated plots was 32%. Two applications of aldicarb, one in February and one in April, reduced the damage to the lowest level of 0.5%. A single application of aldicarb in February, and two applications of imidacloprid—one in February and one in April—reduced the damage to 5-10%. Treatments with imidacloprid in February or in April, reduced the damage to 12-13%. Neither one application of aldicarb in April, nor any of the treatments with isazofos, was effective. In all treatments, larvae of the large narcissus fly were found in only approximately one-third of the damaged bulbs. The level of infestation with the small narcissus fly in the untreated bulbs was only approximately 2%. The effects of the insecticide treatments on the small narcissus fly were similar to those recorded for the large narcissus fly .     

The metabolism of [14C]aldicarb in the root of sugar beet plants

Sugar beet plants were grown in the field, after in-furrow application of [¹⁴C]- aldicarb (3 kg of aldicarb ha^?1) at planting. The ripe sugar beet plants were harvested, and the roots were analysed. The roots were fractionated according to a procedure similar to the normal beet-sugar manufacturing process. Expressed as a proportion of the total radioactivity incorporated into the root, the pulp contained 29.7%, the lime cake 9.7%, the crystallised sugar 17.7% (which gave, with the radioactivity found in the sugar in the molasses, a total of 20.7% of the radioactivity in the total sugar), and the molasses, 42.9%. A part of the labelled carbon from the radio- active aldicarb and its metabolites had thus been metabolised and incorporated into sugar molecules. Except for the radioactivity in the sugar and in the lime cake from the processing, the proportion of radioactive non-conjugated organosoluble compounds was very low (2.6%), and perhaps partially corresponded to the very low amount of aldoxycarb (aldicarb sulphone) in the root (less than 0.001 mg of [¹⁴C]-aldicarb equivalents kg^?1 fresh weight). Hydrolysis of the molasses yielded free radioactive 2-methyl-2-(methylsulphinyl)propan-1-ol (3.1%), 2-mesyl-2-methyl-propan-I-ol (8.9%) and 2-mesyl-2-methylpropionic acid (12.0%) which had been conjugated to plant constituents in the root. The corresponding concentrations (expressed as mg of [¹⁴C]aldicarb equivalents kg^?1 fresh weight of root) were 0.004, 0.011, and 0.016, respectively. No aldicarb, aldicarb sulphoxide or aldoxycarb (nor the corresponding nitrile, generated from aldicarb during the fractionation procedure) was liberated by the hydrolysis, indicating the absence of conjugates of these compounds in the root.     

In vitro inhibition of α-amylase and protease by nematocides in Cicer arietinum L

The in vitro effects of four systemic nematocides, i.e., aldicarb, carbofuran, oxamyl, and phorate, on the α-amylase and protease activities in Cicer arietinum has been revealed. All four nematocides markedly inhibited the activities of both the enzymes, with a general tendency of increased inhibition with corresponding increase in the concentrations of the nematocides. There was complete inhibition of α-amylase activity by the highest concentration (500 μM) of aldicarb and carbofuran, while oxamyl at the same concentration showed the same effects on protease activity. The lowest concentration (10 μM) was almost ineffective.     

Accumulation pattern and insecticidal effect of aldicarb in cotton following soil treatment for the control of the tobacco whitefly (Bemisia tabaci)

The accumulation pattern of the pesticide aldicarb [2-methyl-2-(methylthio) propionaldehyde O-(methylcarbamoyl)-oxime] and of its sulfoxide and sulfone metabolites was studied in field-grown cotton, following soil treatments at various intervals from planting. Control of the tobacco whitefly(Bemisia tabaci) was determined and correlated with the concentration of aldicarb and of its metabolites in cotton leaves. The main constituent found in the leaves was aldicarb sulfoxide, which reached its maximum concentration there at about 22 days post-treatment. Late application of the insecticide (mid-July) resulted in higher concentrations toward the end of the growing season and so gave improved control of the pest. Results are presented for residues in young and mature leaves and in the seeds.     

Application of aldicarb in a drip-irrigated cotton field for the control of the Tobacco Whitefly(Bemisia Tabaci)

Cotton was grown in loess soil, in rows 1 m apart, and drip-lines were placed in the center of every second space between rows at a distance of 50 cm from the plants. Aldicarb was applied as granules (containing 15% a.i.) to the field on two dates (mid-June and mid-July) and incorporated into the soil(a) 25 cm from the plants,i.e., equidistant from the plants and the drip-lines, on both sides of the drip-lines; and(b) 50 cm from the plants,i.e., in the center of the spaçe between the rows, near the drip-line. Measurements of mortality ofBemisia tabaci larvae, and of the accumulation of aldicarb from the late (mid-July) treatment showed that best control of the pest and the highest aldicarb residues were obtained with the late treatment. The pest control effectiveness was found to depend on both date and location of aldicarb application. Early treatment (mid-June) was more effective if applied close (25 cm distance) to the plant stems, whereas late treatment (mid-July) was more effective if applied at a distance of 50 cm from the plant stems.     

高效液相色谱柱后衍生化法检测蔬菜中涕灭威和克百威残留的方法研究

建立了蔬菜中涕灭威和克百威残留的分析方法。样品以乙腈提取,以氨基固相萃取柱净化,甲醇∶二氯甲烷=1∶99（V/V）洗脱,以高效液相色谱柱后衍生系统,荧光检测器检测。在最佳分离条件下,涕灭威和克百威在浓度0.01～1.0mg/L范围内线性关系良好;方法检出限涕灭威为1.4μg/kg,克百威为1.7μg/kg。蔬菜样品中3个添加水平的平均回收率为涕灭威70.6%～82.0%,RSD为5.1%～12.2%;克百威88.0%～98.0%,RSD为1.3%～14.0%。该方法灵敏,准确,适用于蔬菜中涕灭威和克百威的残留检测。     

Acetylcholinesterase of Aphis citricola: Properties and significance in determining toxicity of systemic organophosphorus and carbamate compounds

In apterous adults of the spirea aphid, Aphis citricola van der Goot, the optimum conditions for determining acetylcholinesterase (AChE) activity consist of reaction mixture of 0.1 M phosphate buffer (pH 7.5), 10^?3M acetylthiocholine (ASCh), and enzyme extract equivalent to 80 ± 3 μg protein incubated for 15 min at 30°C. The K_m value for ASCh (6.7 × 10^?5M) was much lower than that of butyrylthiocholine (BuSCh) (1.25 × 10^?2M). The enzyme activity was almost completely inhibited by 10^?6M paraoxon or 10^?5M eserine and was 84% inhibited by 10^?5M BW284C51 (a specific AChE inhibitor). DTNB was found to inhibit the enzyme activity and was therefore added at the end of the reaction. AChE activity of A. citricola was inhibited in vitro and in vivo by dimethoxon > dimethoate, and aldicarb sulfoxide > aldicarb > aldicarb sulfone. The in vivo effect correlates well with the toxicity level of the various toxicants. A neurotoxicity index which combines both mortality and in vivo inhibition of the aphid AChE activity is suggested as a measure for determining the toxicity of organophosphorus and carbamate compounds toward aphids.     

Foliar residues and toxicity to Aphis citricola of three systemic insecticides applied to the soil in a citrus grove

A study was made of the accumulation of aldicarb, ethiofencarb and dimethoate in citrus leaves and fruit; the toxicity of these insecticides to the spirea aphid (Aphis citricola Van der Goot) was also studied. The effectiveness of the treatments was affected mainly by the rate of accumulation of the toxicant in the leaves. At 18 g a.i. per tree, the greatest residues found in the leaves were 106, 12.2 and 1.3 μg 8^?1 fresh weight for aldicarb, ethiofencarb and dimethoate, respectively. The concentration in mature leaves was very similar to that in young leaves. The residue levels in the mature fruits were much lower than in the leaves. The main components of the residues in the leaves were aldicarb sulphoxide [2-methyl-2-(methylsulphinyl)- propionaldehyde O-methylcarbamoyloxime], dimethoate, omethoate and ethiofencarb sulphoxide [2-(ethylsulphinylmethyl)phenyl methylcarbamate]. A laboratory study with synthetic diets showed similar toxicity for all three insecticides, whereas in detached leaves, or when taken up by citrus trees, ethiofencarb was the least toxic to the aphids.     

The effects of dieldrin and isomeric aldrin diols on synaptic transmission in the American cockroach and their relevance to the dieldrin poisoning syndrome

Dieldrin and two of its metabolites, 6,7-trans-dihydroaldrindiol, and 6,7-cis-dihydroaldrindiol, were studied with regard to their toxicity to the American cockroach, effects on ganglia of the ventral nerve cord, and penetration into the ventral nerve cord of poisoned cockroaches. An approximate LD₅₀ for injected doses of dieldrin was 0.45 mg/kg. After injection at 115 mg/kg, the trans isomer of aldrin diol caused about 70%, and the cis isomer about 50% mortality. Injected doses of 40 mg/kg of the three compounds appeared in the ventral nerve cord to the extent of 0.13–0.26% of the doses. Dieldrin was more potent, but slower acting than the diols in causing synaptic after-discharge and elevated spontaneous activity in isolated nerve cords. The results are discussed in relation to other studies on these compounds. It was concluded that, in the American cockroach, dieldrin, rather than either of the diols, is the insecticidal agent in dieldrin poisoning, and that metabolic conversion of dieldrin to the cis and/or trans aldrindiol constitutes a detoxification.     

Effect of pyrethroid insecticides on EEG activity in conscious,immobilized rats

Preseizure and seizure EEG patterns elicited by the pyrethroid insecticides, deltamethrin and cis-permethrin, were compared in immobilized Sprague-Dawley rats. Deltamethrin (1–3 mg/kg, iv) produced a preseizure EEG pattern of high-amplitude, slow, 2- to 5-Hz synchronized cortical waves or spike-wave complexes. cis-Permethrin (20–40 mg/kg, iv) elicited an immediate EEG change characterized by 6- to 12-Hz high-amplitude waves with intermingled high-voltage spikes. DDT (50–70 mg/kg, iv) produced a sustained EEG activation similar to that seen after cis-permethrin, but of higher frequency. All three insecticides produced generalized EEG seizure activity, but this was more prominently associated with poisoning due to deltamethrin. cis-Permethrin and DDT gave rise to EEG seizures only at lethal doses. Electrodes stereotaxically positioned in ventral hippocampus, caudate, putamen, thalamus, septum, red nucleus, and cerebellum detected no preferential activation of any of these subcortical sites in either preconvulsive or convulsive phases of poisoning. These results indicate that both deltamethrin and cis-permethrin can have marked effects on mammalian EEG activity. This does not support the hypothesis of differing sites of action, i.e., peripheral vs. central, for the two types of compound. The more pronounced seizure-inducing action of deltamethrin may instead reflect a greater efficacy of cyanopyrethroids at target sites within the central nervous system.     

Accumulation of hyperparasites of Rhizoctonia solani by addition of live mycelium of R. solani to soil

Addition of live mycelium ofRhizoctonia solani to three slightly, acid sands collected in winter from a field after a previous potato crop resulted in accumulation of hyperparasites and less infestation of sprouts of infected seed potatoes. A similar effect was observed in alkaline marine sandy loam soils, but only after a second addition of live mycelium. The predominant hyperparasite in these experiments wasVerticillium biguttatum.     

The metabolism of [14C]aldicarb in the leaves of sugar beet plants

Sugar beet plants were grown in the field, after in-furrow application of [¹⁴C]aldicarb (3 kg of aldicarb ha^?1) at planting. The ripe sugar beet plants were harvested, and the blades and petioles of the leaves were analysed separately. In the whole leaves, 15% of the ¹⁴C (all the percentages of ¹⁴C are relative to the total ¹⁴C incorporated into the whole leaves) was insoluble in ethanol+ water (1+1 by volume), 31% was organo-soluble (and thus unconjugated in the leaves), and 54% was water-soluble (mainly conjugated to plant constituents). The weights and concentrations (as aldicarb equivalents) of various identified metabolites of aldicarb, incorporated into the leaves, were determined; no aldicarb, as such, was detected.     

Assessment of leaching potential of aldicarb and its metabolites using laboratory studies

The metabolites of pesticides can contaminate groundwater and pose a risk to human health when this water is used for drinking. This paper reports the results of a laboratory study on aldicarb and its main metabolites, aldicarb sulfone and aldicarb sulfoxide. Aldicarb and its metabolites showed K_oc values (6–31) which were lower than that of atrazine (55), indicating that they are very mobile in soil. They are less persistent than atrazine (DT₅₀ = 25 days), with DT₅₀ values from less than 1 day and up to 12 days. Aldicarb behaved as a non‐leacher, whereas its metabolites clearly showed the characteristics of leachers. Aged residue leaching experiments showed that aldicarb can occur at high concentrations in the leachate, together with its two metabolites. The leachate composition depends on the incubation time of the parent compound. Aldicarb and its metabolites can form various mixtures in groundwater on the basis of the time elapsing between the application of the insecticide and the first significant rainfall. This study confirms the characteristics of contaminants of aldicarb and especially its metabolites, as reported in the literature. © 2001 Society of Chemical Industry