Residues of synthetic pyrethroid insecticides on horticultural crops

Foliar applications of synthetic pyrethroids were made to several crops to determine residue levels at various intervals after application. On onions, residues of cypermethrin, permethrin and fenvalerate were negligible > 0.1 mg kg^?1, 7 days after application. On lettuce, residues of fenvalerate and permethrin were 0.8 mg kg^?1. On celery, residues of fenvalerate did not decline and ranged from 0.12 to 0.25 mg kg^?1 during the 14-day period. On green bush-beans, residues of permethrin and cypermethrin did not decline during the 14-day period and ranged from 0.1 to 0.6 mg kg^?1. By day 7, residues of cyfluthrin, cypermethrin, deltamethrin, fenvalerate and permethrin on strawberries were less than the acceptable maximum tolerance of 0.1 mg kg^?1 with the exception of cypermethrin, applied at the rate of 0.14 kg a.i. ha^?1 which gave a residue of 0.14 mg kg^?1.     

Persistence and safety evaluation of synthetic pyrethroids on sweet orange fruits

The residues of four synthetic pyrethroids from two spray concentrations per compound on sweet orange fruits dissipated at the respective half-life values of 2.45 and 3.15 days for 0.015 and 0.02% fenvalerate; 2.28 and 2.58 days for 0.015 and 0.02% permethrin; 1.73 and 2.12 days for 0.0075 and 0.01% cyper-methrin ; and 2.6 and 2.9 days for 0.0015 and 0.002% deltamethrin, respectively. However, the comparative persistence of synthetic pyrethroids on the rind of sweet orange fruits in the tropical belt in India was found to be in the order of fenvalerate = permethrin > cypermethrin > deltamethrin. No residues were detected in the fruit pulp.     

Dynamics of pesticide residues in the autumn Chinese cabbage (Brassica chinensis L.) grown in open fields

Residues of the pesticides chlorpyrifos, dimethoate, cyhalothrin, cypermethrin, fenvalerate, deltamethrin and chlorothalonil in the autumn Chinese cabbage (Brassica chinensis L.) were studied using gas chromatography. The results indicated that the residues were dependent on the frequency and rate of pesticide application and on the weather conditions immediately following spraying. When the Chinese cabbages were treated once at normal rates, the half-lives of the seven pesticides in the vegetable were 4.7, 5.3, 2.9, 3.5, 5.4, 4.3 and 4.0 days respectively. Thus, based on the recommended preharvest intervals, the residual levels of all pesticides were within the national standards. When the Chinese cabbages were treated four times at maximal rates at 5 day intervals, the half-lives of chlorpyrifos, cypermethrin and chlorothalonil in the vegetable were 3.6, 2.9 and 5.9 days respectively, so that, based on the recommended preharvest intervals, the residual levels of chlorpyrifos and chlorothalonil exceeded the national standards for pollution-free vegetables, but the residual level of cypermethrin was within the national standard. Effects of rain on pesticide final residues in plants treated four times were more significant than in those treated once.     

Dissipation rates of insecticides in six minor vegetable crops grown on organic soils in Ontario,Canada

Dissipation rates of diazinon, endosulfan, leptophos, methamidophos, methomyl, parathion and pirimicarb were studied on five minor vegetable crops, including cos and head lettuce, endive, cauliflower and Chinese cabbage. Residues from foliar treatment generally followed an exponential rate of decline. The number of days for residues to drop to below acceptable tolerances was highly dependent on the magnitude of the initial residue; large variations in initial residues were observed between years, between insecticides, and between crop types. Residues of five insecticides and two fungicides used in furrow treatments for onions intended for pickling were determined in the onions at harvest and after pickling. Fensulfothion and fonofos levels were below the accepted tolerance of 0.1 mg kg^?1 at harvest, while chlorfenvinphos, chlorpyrifos and ethion were present above this level; fungicide residues were not detected. Following pickling, only ethion residues were still present in the onions at levels greater than 0.1 mg kg^?1.     

Dissipation of three organochlorine and four pyrethroid pesticides sprayed in a greenhouse environment during hydroponic cultivation of gerbera

A wide range of pesticides (insecticides, acaricides and fungicides) is used in the hydroponic cultivation of gerbera. The fate and behaviour of some of these commonly used pesticides (organochlorine and pyrethroid insecticides/acaricides) in a greenhouse installation was investigated. The concentrations of endosulfan, dicofol, tetradifon, permethrin, bifenthrin, cypermethrin and deltamethrin in the air of the greenhouse were related to their physicochemical properties and respective application rates. Of these compounds, endosulfan exhibited the highest concentration in the greenhouse air 2 h after application (10 microg m(-3)), due to its highest volatility; afterwards, up to 12 h post-application, a rapid decrease was recorded which finally led to a concentration of 0.41 microg m(-3) at 6 days post-application. Dicofol exhibited the same trend of dissipation in the greenhouse air; its concentration decreased from 0.27 microg m(-3) immediately after the application to 0.12 microg m(-3) at 6 days post-application. Tetradifon, bifenthrin and permethrin were found at concentrations lower than 0.1 microg m(-3) at 2 h post-application, and cypermethrin and deltamethrin could not be detected. The concentrations of all the above pesticides in the drain water of the open hydroponic system were relatively high immediately after application and decreased rapidly during the following 3 days. In the closed hydroponic system, all the pesticides accumulated in the nutrient solution during the first 24 h after application and slowly decreased in concentration over the following 3 days. The spray operators applying these pesticides were exposed to rather high concentrations and the spray deposits were monitored on the chest and forehead of the operator. Endosulfan exhibited the highest concentrations of the seven pesticides. The organochlorine pesticides (endosulfan, dicofol and tetradifon) were usually detected at higher concentrations on the chest than on the forehead of the operator; pyrethroids were detected at higher concentrations on the forehead than on the chest of the operator.     

白芍和黄连中十五种有机氯和拟除虫菊酯类 农药的多残留分析方法

建立了白芍和黄连两种中药材中六六六、滴滴涕、艾氏剂、五氯硝基苯、甲氰菊酯、氯菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯等农药的多残留气相色谱分析方法。在索氏提取器中以石油醚(60~90℃)为溶剂提取样品,提取液经氧化铝与弗罗里硅土的混合柱净化,采用农残分析专用柱农残Ⅱ 柱分离,GC-ECD检测器检测农药的残留量。方法的最小检出量(LOD)为0.000 5~0.006 0 ng, 最低检测浓度(LOQ)为0.005~0.050 mg/kg;3个添加水平农药的平均回收率为79.8％~114.6％,相对标准偏差(RSD)均小于10％ (n=6) 。     

Residues in blackcurrants,fodder peas,spinach and potatoes treated with sublethal doses of 2,4,5-T to simulate wind drift damage

Blackcurrants, treated with 0.1 kg of 2,4,5-T ha^?1 (as esters of mixed C₄–C₆ alcohols; ‘Tormona 80’), contained 0.1 mg of 2,4,5-T residues kg^?1 in the berries at ripeness 29 days after treatment. Total residues in the berries were not reduced during growth and ripening, although the residue concentrations declined in the same period due to growth dilution. In spinach leaves from old plants, treated with 0.1 kg ha^?1, 0.05 mg of 2,4,5-T kg^?1 was found 14 days after treatment. Fodder peas showed no residues (< 0.002 mg kg^?1) at harvest 62 days after treatment with 2,4,5-T esters. After application of 0.1 kg ha^?1 on potato plants, the disappearance of 2,4,5-T was rapid during the first month, but residues were translocated into the tubers and reached a constant level of 0.02 mg kg^?1 after 1 month until harvest at 108 days after treatment. In all crops, visible effects were observed after treatment with 0.1 kg ha^?1. After the application at 0.01 kg ha^?1, phytotoxic effects were observed only in blackcurrants, but negligible residues were found in all the test crops.     

Permethrin and deltamethrin residues on lettuce

Permethrin and deltamethrin, two synthetic pyrethroid insecticides, are registered in several countries for use on lettuce. Both chemicals were applied on autumn and spring grown lettuce in the glasshouse. When applied at the normal prescribed dose rates of 25 and 12.5 g a.i. ha^?1, < 1 mg kg^?1 of either compound was found in the lettuce at harvest, even when applied only a few days before harvest. The total amount of active ingredient applied was too low to reach the 1 mg kg^?1 level when evenly applied on marketable lettuce heads weighing about 200 g each. Applying a higher dose than 25 g permethrin a.i. ha^?1 or 12.5 g deltamethrin a.i. ha^?1, or applying two applications in the 2 weeks prior to harvest, may well result in residue levels higher than the maximum residue limit of 1 mg kg^?1 for permethrin and certainly higher than the maximum residue limit of 0.2 mg kg^?1 for deltamethrin, which is more persistent.     

气相色谱法检测辣椒中7种拟除虫菊酯类农药残留

建立并优化了新鲜辣椒中甲氰菊酯、高效氯氟氰菊酯、氯菊酯、氟氯氰菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯7种拟除虫菊酯类农药残留的气相色谱(GC-μECD)分析方法。采用50 mL V(乙腈):V(水)=3:1的混合溶剂提取,二氯甲烷萃取, N-正丙基乙二胺(PSA)净化,HP-1毛细管色谱柱分离,气相色谱-电子捕获检测器(GC-μECD)测定。在添加水平为0.017~0.64 mg/kg下的平均回收率为74.0%~105.6%,相对标准偏差为3.3%~15%。该方法准确、灵敏,可同时测定辣椒中7种拟除虫菊酯类农药的残留量。     

菊酯类农药在中草药白菊花中的多残留分析方法研究

报道了采用气相色谱仪、电子捕获检测器同时测定 4种菊酯类农药 (甲氰菊酯、氯氰菊酯、氰戊菊酯和溴氰菊酯 )在中草药白菊花中的残留分析方法。添加浓度分别为 1.0、0 .1、0 .0 1mg/ kg,白菊花中的回收率分别为 86 %～ 10 4 % ,87%～ 95 %和 81%～ 99% ,n=5 ,最低检测量 8.3× 10-4～ 2 .8× 10-3 ng。该方法简便、准确、分离效果好、回收率高。     

The uptake of metabolites of permethrin by plants grown in soil treated with [14C]permethrin

Sugar beet, wheat, lettuce and cotton were grown in soil treated with [¹⁴C]permethrin, the crops being sown at intervals of 30, 60 and 120 days after treatment of the soil. The uptake of radioactive residues into these crops was measured. Low radioactive residues (up to 0.86 μg g^?1) were detected in the mature plants sown 30 days after soil treatment, and this uptake declined significantly as the interval between soil treatment and sowing increased. Metabolites derived from the acid moiety of the permethrin molecule were shown to constitute the greater part of the residue transferring from the soil to the crops. (1RS)-cis- and (1RS)-trans-3-(2,2-dichlorovinyl)- 2,2-dimethylcyclopropanecarboxylic acid and 3-(2,2-dichlorovinyl)-1-methylcyclopropane-1,2-dicarboxylic acid were identified as the major acidic metabolites. The latter compound is a metabolite of permethrin which has not previously been identified in soil or plants.     

Residue distribution of the acaricide coumaphos in honey following application of a new slow-release formulation

Acaricide used in beehives for the control of varroa often leaves residues in bee products. The behaviour and distribution of the acaricide coumaphos in honey following the application of a new slow-release strip formulation (CheckMite+) was assessed. The bee colonies were allowed to build new combs without foundation, and two strips were hung in the brood chamber of each colony for a period of 42 days. The distribution of coumaphos residues in honey in relation to the position of the frame and the duration of treatment was examined by collecting samples from each comb at various time intervals up to 145 days after treatment. In the brood chamber, coumaphos was incorporated into honey from the first day of application, and residues accumulated mainly in combs placed next to strips. In the adjacent combs, residues remained at low concentrations with slight variations. In the honey chamber, residue concentrations on the day of strip removal ranged between 0.006 and 0.020 mg kg(-1), while 79 days after application the concentration of coumaphos residues was below 0.020 mg kg(-1). Residues above the EC fixed maximum residue limit (MRL) of 0.1 mg kg(-1) were measured only in brood chamber honey obtained from those combs placed next to strips. In these samples, 0.060-0.111 mg kg(-1) of coumaphos was detected up to 103 days after strip removal. Coumaphos residues in honey extracted from combs that were placed at the edge of the brood chamber were found below the MRL value, even during the 42 day period of CheckMite+ strip treatment.     

Excretion,distribution and depletion of [14C]cypermethrin and cis and trans isomers of 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid administered orally to laying hens

Radiolabelled racemic cypermethrin, and the cis and trans isomers of 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (labelled at C-1 of the cyclopropane ring) were each separately administered orally in feed for three consecutive days to White Leghorn laying hens. The amount of individual compound dosed was approximately 7.5 mg per hen per day. Radiocarbon was eliminated very rapidly in excreta. Tissue residues were generally very low with the exception of fat depots, but trace amounts of radiocarbon residues were still detectable in fat, liver and kidney 11 days post-treatment. Residues were detected in the egg albumen of hens treated with cypermethrin and cis isomer of the acid, but none was detected from trans acid. Metabolites identified included products arising from the hydrolysis of the ester bond of cypermethrin, followed by oxidative attack on one or both methyl groups. The rate of oxidative attack on methyl groups was influenced by the geometry of the dichlorovinyl group. On the basis of the metabolites identified a metabolic pathway for cypermethrin in laying hens was proposed which included hydrolysis of the ester bond followed by oxidation of methyl group(s). The data indicate that use of cypermethrin as recommended should not produce residues in eggs and meat of laying hens at levels that are of toxic concern.     

Residues of zeta‐cypermethrin in bovine tissues and milk following pour‐on and spray application

The depletion of zeta‐cypermethrin residues in bovine tissues and milk was studied. Beef cattle were treated three times at 3‐week intervals with 1 ml 10 kg^?1 body weight of a 25 g litre^?1 or 50 g litre^?1 pour‐on formulation (2.5 and 5.0 mg zeta‐cypermethrin kg^?1 body weight) or 100 mg kg^?1 spray to simulate a likely worst‐case treatment regime. Friesian and Jersey dairy cows were treated once with 2.5 mg zeta‐cypermethrin kg^?1 in a pour‐on formulation. Muscle, liver and kidney residue concentrations were generally less than the limit of detection (LOD = 0.01 mg kg^?1). Residues in renal‐fat and back‐fat samples from animals treated with 2.5 mg kg^?1 all exceeded the limit of quantitation (LOQ = 0.05 mg kg^?1), peaking at 10 days after treatment. Only two of five kidney fat samples were above the LOQ after 34 days, but none of the back‐fat samples exceeded the LOQ at 28 days after treatment. Following spray treatments, fat residues were detectable in some animals but were below the LOQ at all sampling intervals. Zeta‐cypermethrin was quantifiable (LOQ = 0.01 mg kg^?1) in only one whole‐milk sample from the Friesian cows (0.015 mg kg^?1, 2 days after treatment). In whole milk from Jersey cows, the mean concentration of zeta‐cypermethrin peaked 1 day after treatment, at 0.015 mg kg^?1, and the highest individual sample concentration was 0.025 mg kg^?1 at 3 days after treatment. Residues in milk were not quantifiable beginning 4 days after treatment. The mean concentrations of zeta‐cypermethrin in milk fat from Friesian and Jersey cows peaked two days after treatment at 0.197 mg kg^?1 and 0.377 mg kg^?1, respectively, and the highest individual sample concentrations were 2 days after treatment at 0.47 mg kg^?1 and 0.98 mg kg^?1, respectively. © 2001 Society of Chemical Industry     

Repellent action of permethrin,cypermethrin and resmethrin against black flies (Simulium spp.) attacking cattle

Permethrin, cypermethrin, and resmethrin were tested under field conditions as repellents to protect cattle from black flies (Simulium spp.). The chemicals were applied topically to the entire body surface of steers. Ethanolic solutions of technical permethrin, at doses of 1, 2, 4 and 6 mg a. i. kg^?1 of body weight, effectively repelled black flies by preventing at least 70% of the flies present from taking a blood meal for up to 8 days, and for at least 11 days at a dose of 12 mg a. i. kg^?1. Aqueous mixtures of a 20% permethrin emulsifiable concentrate (e. c.), at doses of 1, 2 and 6 mg a. i. kg^?1, effectivelyrepelled black flies for 2, 10 and 11 days, respectively. Aready-to-use 5% permethrin dust, at doses of 1, 2, and 4 mg a. i. kg^?1, effectively repelled black flies for 4, 5 and 8 days, respectively. Ethanolic solutions of technical cypermethrin, at doses of 1 and 2 mg a. i. kg^?1, repelled black flies for 3 and 4 days, respectively. Aqueous mixtures of a 40% cypermethrin e. c., at doses of 2 and 4 mg a. i. kg^?1, repelled black flies for at least 5 days. Ethanolic solutions of technical resmethrin, at doses of 2 and 6 mg a. i. kg^?1, repelled black flies for 1 and 2 days, respectively.     

Residues of cypermethrin,fenvalerate and deltamethrin on cauliflower

Following the application of Cypermethrin, fenvalerate and deltamethrin to a cauliflower crop at rates of 50, 50 and 12 g a.i. ha^-1, the maximum initial deposits of these insecticides on heads and leaves were 1.10 and 0.75, 1.14 and 0.60, and 0.32 and 0.12 mg kg^-1, respectively. These residue values for fenvalerate were less than the maximum residue limit (MRL) of 2 mg kg^-1 for this crop. While the maximum initial deposits of Cypermethrin and deltamethrin on cauliflower leaves were less than their respective MRL values of 1 and 0.2 mg kg^-1 for brassica leafy vegetables, it took one day for their residues on cauliflower heads to decline below this level.     

Binary mixtures of pyrethroids produce differential effects on Ca influx and glutamate release at isolated presynaptic nerve terminals from rat brain

Isolated rat brain synaptosomes were used to evaluate the action of pyrethroid mixtures on Ca²⁺ influx and subsequent glutamate release under depolarizing conditions. In equipotent binary mixtures at their respective and/or estimated EC₅₀s with deltamethrin always as one of the two components, cismethrin, λ-cyhalothrin, cypermethrin, esfenvalerate and permethrin were additive and S-bioallethrin, fenpropathrin and tefluthrin were less-than-additive on Ca²⁺ influx. In binary mixtures with deltamethrin always as one of the two components, esfenvalerate, permethrin and tefluthrin were additive and λ-cyhalothrin was less-than-additive on glutamate release. Binary mixture of S-bioallethrin and cismethrin was additive for both Ca²⁺ influx and glutamate release. Only a subset of pyrethroids (S-bioallethrin, cismethrin, cypermethrin, and fenpropathrin) in binary mixtures with deltamethrin caused a more-than-additive effect on glutamate release. These binary mixtures were, however, only additive (cismethrin and cypermethrin) or less-than-additive (S-bioallethrin and fenpropathrin) on Ca²⁺ influx. Therefore, increased glutamate release evoked by this subset of pyrethroids in binary mixture with deltamethrin is not entirely occurring by Ca²⁺-dependent mechanisms via their action at voltage-sensitive calcium channels. These results suggest that pyrethroids do not share a common mode of toxicity at presynaptic nerve terminals from rat brain and appear to affect multiple target sites, including voltage-sensitive calcium, chloride and sodium channels.     

Efficacy of insecticide mixtures against pyrethroid‐ and organophosphate‐resistant populations of Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND: Spodoptera litura (F.) is an important pest worldwide, with over 112 host plants, and is exposed to insecticides throughout the year, resulting in the rapid development of resistance. Insecticide mixtures can delay the development of resistance more effectively than sequences or rotations. Cypermethrin, deltamethrin, profenofos, chlorpyrifos and fipronil were assessed separately and in mixtures against laboratory susceptible S. litura and two field‐collected populations. RESULTS: The field‐collected population from Khanewal (KWL) was significantly more resistant to cypermethrin, deltamethrin, chlorpyrifos and profenofos than one collected from Muzaffar Garh (MGH). Mixtures of cypermethrin + chlorpyrifos or profenofos and of deltamethrin + chlorpyrifos or profenofos at 1:1, 1:10 and 1:20 ratios significantly increased (P < 0.01) toxicity to cypermethrin and deltamethrin in field populations. The combination indices of cypermethrin + chlorpyrifos at 1:1 and 1:10 ratios and cypermethrin + fipronil at 1:1, 1:10 and 1:20 ratios for the KWL strain and of cypermethrin + profenofos or fipronil at 1:1, 1:10 and 1:20 ratios for MGH were significantly below 1, suggesting synergistic interactions. The inhibitors DEF and PBO largely overcame resistance to deltamethrin, cypermethrin and profenofos, suggesting that resistance to the insecticides was associated with esterase and monooxygenase detoxification respectively. CONCLUSION: Chlorpyrifos, profenofos and fipronil could be used in mixtures to restore cypermethrin and deltamethrin susceptibility. These findings may have considerable practical implications for S. litura resistance management. Copyright © 2008 Society of Chemical Industry     

Contact activity of synthetic pyrethroids against adult grass grub,Costelytra zealandica (white)

The field life for contact activity of cypermethrin and permethrin, applied to pasture, was similar for all of five application rates between 0.25 and 1.5 kg ha^?1. Laboratory bioassays with grass grub beetles, Costelytra zealandica (White), showed that the insecticides lost their activity after about 4–9 days on pasture. Microencapsulation significantly increased the active field life of permethrin.     

Field evaluation and economics of insecticides against the major pests of okra

Abstract

Bio‐efficacy of 15 insecticides was evaluated against the pest complex of okra in the semi‐arid region of Rajasthan during July‐October, 1984. Five sprays given at intervals of 15 days throughout the crop period indicated that fenvalerate (0.02%) was most effective, followed by permethrin (0.02%), cypermethrin (0.02%), carbaryl (0.10%), monocrotophos (0.04%) and dimethoate (0.03%), against leafhoppers, aphids and fruit borer. The maximm yield of marketable fruits was obtained with fenvalerate, followed by cypermethrin, carbaryl, monocrotophos and dimethoate treatments. Highest net‐profit of Rs. 4890.00 was also recorded with fenvalerate treatment, followed by Rs. 4430.00 with carbaryl, Rs. 4148.00 with permethrin, Rs. 3977.00 with monocrotophos and Rs. 3053.00 with dimethoate treatments. A higher benfit cost ratio was found with carbaryl (1:9.78), followed by dimethoate (1:7.85), monocrotophos (1:5.18), methyl demeton (1:5.07), fenvalerate (1:3.43) and permethrin (1:2.41). These insecticides can also be used against insect pests of other vegetable crops of the season.