Permethrin as a residual insecticide against cockroaches

The pyrethroid permethrin was shown to be active against Blattella germanica, Periplaneta americana and Blatta orientalis. In laboratory tests on plywood panels the best formulation was a 25% wettable powder which showed an initial LC₅₀ of 10 mg m^?2 against B. germanica and lost activity at the weekly rate of 1.9 mg m^?2. An initial deposit of 108 mg m^?2 gave 50% kill after one year. The synergist piperonyl butoxide diminished residual performance. In one field trial, good control was maintained for more than four months with an initial deposit of 50 mg m^?2, the smallest dose used. From this and other trials, the recommended rate of application for general use in long-term control is 100 mg m^?2. A distinctive slow expellent action against B. germanica was seen in field trials.     

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.     

The persistence and activity of insecticide spary deposits on woven polypropylene fabric

Wettable powder formulations of the organophosphorus insecticides, fenitrothion and pirimiphos-methyl, and the pyrethroids, permethrin and deltamethrin, have been compared for persistence and activity on woven polypropylene fabric; the residues produced in maize kept under the test sheets have also been measured. The test insects were Sitophilus oryzue (L.) and Tribolium custuneum (Herbst). Permethrin at 41 and 83 mg m^?2 was completely effective for the full 12 weeks of the experiment. Deltamethrin at 6.2 and 12.5 mg m^?2 was almost equally effective but after 4 weeks the deposit was slower acting against S. oryzae. The organophosphorus compounds were effective only up to 2 weeks at 250 mg m^?2 and up to 4 weeks at 500 mg m^?2. No residues could be detected under the pyrethroids but the organophosphorus insecticides gave residues of 2–4 mg kg^?1 on a thin layer of grain. This residue was biologically effective against the test insects.     

Residues of methomyl in strawberries,tomatoes and cucumbers

An accurate and rapid high performance liquid chromatography method was developed to monitor residues of methomyl in plant extracts. The rate of disappearance of foliage-applied methomyl from strawberries, tomatoes and cucumbers was studied. Residues reached levels of 0.55, 0.2 and 0.6 mg kg^?1 seven days after methomyl had been applied to strawberries, tomatoes and cucumbers, respectively. Results also showed that rinsing treated fruits with tap water removed considerable amounts of methomyl. Samples of strawberries, tomatoes and cucumbers were collected from local markets at Ismailia, and checked for methomyl residues. Residues in 12.5% of tomato and 25% of strawberry samples were above 0.2 mg kg^?1.     

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.     

Evaluation of permethrin for the protection of cattle against mosquitoes (diptera: Culicidae), applied as electrostatic and low pressure sprays

Permethrin was tested for the protection of cattle against field populations of mosquitoes. Permethrin (500 ml of a permethrin 4·0 g liter^?1 aqueous emulsion) applied with a ‘Dual-Cloud’ electrostatic sprayer was effective in providing coverage of the cattle body surface of a group of four animals; 100 ml of a permethrin 5·0 g liter^?1 aqueous emulsion applied with a ‘Dual-Cloud'’ electrostatic sprayer as a total body spray to a yearling heifer provided 70% or better protection from field populations of mosquitoes for at least 72 h; 500 ml of a permethrin 1·0 g liter^?1 aqueous emulsion applied as a low-pressure spray to the body of a yearling heifer provided 70% or better protection from mosquitoes for at least 140 h. Permethrin applied as a total body-spray thus provides adequate protection to cattle from field populations of mosquitoes.     

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.     

Laboratory assessment of different methods of applying a commercial granular bait formulation of methomyl to control adult houseflies (Musca domestica l.) in intensive animal units

Female houseflies (Musca dornestica L.) from a susceptible and a multiinsecticide-resistant strain were used to evaluate the toxicity of a granular insecticide bait formulation of the carbamate insecticide methomyl. The bait was either applied to a polystyrene bait target, or scattered over the floor of the fly treatment cages. Targets were treated with methomyl granules dissolved in water with and without apaste carrier or the granules were applied directly to the target using an adhesive. Scattered methomyl granules proved the most effective of the various treatments assessed. Based on the KT₉₀ values, the most effective suspended bait treatments against susceptible or resistant flies were water as a carrier, and egg or ‘Lap’ wallpaper paste as adhesives; the least effective were ‘Polycell’ regular wallpaper paste as an adhesive and carboxymethylcellulose as a carrier. A proportion of flies from both the susceptible and the resistant strain recovered from knockdown; most of these lost their ability to fly (‘hoppers’) and subsequently survived the treatments. When bait targets treated with methomyl granules were fixed at right angles to the wall/floor junction of the treatment cages most of the recovered flies fed again on the bait and received a lethal dose. The mortality of flies exposed to suspended bait targets was influenced by the level of light. For both strains of fly, mortality decreased as the light intensity was lowered; this effect was more pronounced with the resistant strain. The implication of these results for the application of methomyl bait is discussed.     

Protective action of fenvalerate,deltamethrin, and four stereoisomers of permethrin against black flies (Simulium spp.) attacking cattle

Fenvalerate, deltamethrin, (1R)-cis-permethrin, (1R)-trans-permethrin and (1S)-trans-permethrin, applied topically to the entire body surface of steers at a rate of 1 mg a.i. kg⁻¹, provided 70% or better protection from black flies on cattle for 16, 9, 8, 6 and 6 days, respectively. The (1S)-cis stereoisomer of permethrin was ineffective as a protectant against black flies at a rate of 1 mg a.i. kg⁻¹ when applied as a total body spray. One poly(vinyl chloride) ear tag containing 10% permethrin, in each ear of steers, provided protection from black fly attack for up to 13 days under field conditions. Poly(vinyl chloride) ear tags containing 8% fenvalerate, installed in each ear of steers, did not provide satisfactory protection from black flies under field conditions.     

Off-target glyphosate from aerial silvicultural applications,and buffer zones required around sensitive areas

Off-target glyphosate deposits were measured downwind of aerial silvicultural applications which used D8-46 hollow-cone hydraulic nozzles, ‘Micronair’ AU 5000 rotary atomisers, and the ‘Thru Valve Boom’ (030), with volume application rates of 35, 20 and 20 litre ha^?1 respectively, and a glyphosate application rate of 2·1 kg ha^?1. Crosswind spray lines were released 10 m above ground level over a short forest canopy, from a fixed-wing aircraft flying at 45 m s ¹ in atmospheric boundary layers with average wind speeds and air temperatures of 2·2-3·7 m s^?1 and 8-23°C at release height. Ground sheets and artificial foliage clusters were exposed at downwind distances of between 50 and 300 m. Glyphosate deposit measurements at various downwind distances (x) were fitted with non-linear regression lines; deposits were attenuated at rates inversely proportional to x at powers of 1·3-2·3. For a particular trial, deposits on ground sheets and artificial foliage were generally similar, and ranged between 19 and 0·04 mg m^?2 over the sampling distances used. For 100-ha applications the estimated buffer-zone widths around water bodies were less than 50 m, whereas those around non-target vegetation ranged between 75 and 1200 m, depending on the application method and the meteorological conditions.     

Pyrethroid insecticide resistance and treated bednets efficacy in malaria control

Most of the studies on insecticide impregnated bednets efficacy in malaria control have been undertaken in areas where mosquitoes are pyrethroid susceptible. The efficacy of pyrethroid-treated bednets was not compromised even when mosquitoes were kdr resistant. Here, we evaluate a case in which mosquitoes have kdr-like pyrethroid resistance coupled with metabolic mechanisms. Metabolic and kdr-resistance mechanisms in Anopheles stephensi were characterised in our previous study and this easily colonised species was used as a model to examine the efficacy of pyrethroid-treated bednets in the laboratory. Bioassays performed on adults of susceptible (Beech) and resistant (DUB-S) strains using WHO 0.75% permethrin-impregnated papers showed a resistance ratio of 9.75. The recovery rate of the mosquitoes of the DUB-S strain was significantly higher than that of the susceptible strain Beech. The overall permethrin metabolism rates by DUB-S, measured by HPLC method, were 1.5-fold more than by Beech strain. Bioassays performed on DUB-S mosquitoes using different pyrethroid-treated bednets showed that only deltamethrin at 25 mg/m² and α-cypermethrin at 40 mg/m² produced adequate mortality rates. Four other pyrethroids, including permethrin, were ineffective. The deterrency test performed on susceptible and resistant An. stephensi showed that there are significant differences between the entry rates of susceptible and resistant mosquitoes into the exposure tube containing permethrin-treated bednet. These data show that when mosquitoes have both kdr-type and metabolic resistance mechanisms, the efficacy of pyrethroid-treated bednets is questionable.     

The resistance to eighteen toxicants of a strain of Musca domestica L. collected from a farm in England

A sample of houseflies initially collected from a pig farm and found to be resistant to bendiocarb, DDT, gamma-HCH, pyrethrins + piperonyl butoxide (PB), tetrachlorvinphos and trichlorfon, was tested for resistance to knockdown by other toxicants. At the KD₅₀ response level, resistance factors were obtained for: permethrin (× 141), deltamethrin (×96), bioresmethrin + PB (×37), resmethrin + PB (×33), fenitrothion (×94), bromophos (×58), iodofenphos (×42), pirimiphos-methyl (×30), dichlorvos (×22), dimethoate (×9), diazinon (×8), methomyl (×4) and methomyl + PB (×4). The slopes of the dose–response lines were lower for the farm strain than for a susceptible strain. This resulted in an increase of resistance factors at the KD₉₅ level by an average of × 1.6. The houseflies on the farm could not be controlled using space sprays of pyrethrins + PB, although resistance to this toxicant was only ×12. However, control was achieved with a methomyl bait.     

Impact of two synthetic pyrethroids and methomyl on management of the cabbage aphid,brevicoryne brassicae (L.) and its associated parasitoid,diaeretiella rapae (M'Intosh)

The effectiveness of two synthetic pyrethroids, cypermethrin and fenvalerate, and of methomyl applied to cabbage plants was tested against the cabbage aphid, Brevicoryne brassicae (L.), and its parasitoid, Diaeretiella rapae (M'Intosh). Dosage rates chosen were equivalent to the manufacturer's maximum and minimum recommendations. Methomyl was considerably more toxic to B. brassicae adults than the two synthetic pyrethroids used. Fenvalerate, at the lowest rate used (71 g ha^?1), showed satisfactory effectiveness in reducing aphid adult population on treated plants by c. 77% below that of the control. All insecticides and rates used significantly reduced the emergence of parasitoid adult D. rapae from mummified aphids compared to the control. Fenvalerate clearly had less impact on emergence than cypermethrin or methomyl at any dosage used, while methomyl has appeared to be the most toxic compound in this respect. Longevity of parasitoid adults was highly affected by insecticide application, particularly those adults emerging from mummified aphids exposed to methomyl or cypermethrin. However, only a slight difference in longevity was seen at the lower rate of 71 g ha^?1 of fenvalerate. At the lowest dosage rates used, methomyl and cypermethrin reduced the F₁-progeny of adult parasitoid females by 70.5% and 58.3%, respectively, of the control, whereas fenvalerate reduced the progeny by only 36.4%.     

Near‐field air concentrations of pesticides in potato agriculture in Prince Edward Island

BACKGROUND: Pesticides in air have become of increasing concern in recent years. This study examined downwind air concentrations of carbofuran, methamidophos, mancozeb and diquat dibromide resulting from spray drift within 24 h of application, within 100 m of potato fields. RESULTS: Concentrations ranged from less than 0.05 µg m^?3 in prespray samples to 6.37 µg m^?3 for methamidophos at 3 h post‐spray. For most applications, air concentrations decreased with distance from the field and with time after application. Methamidophos concentrations in the air downwind continued to increase up to 3 h after spray. Air concentrations during spray were positively correlated with application rate (r = 0.904), and air concentrations at 1 h and 3 h post‐spray were positively correlated with vapour pressure (r = 1.000 and r = 0.999 respectively). Carbofuran, methamidophos and diquat dibromide concentrations during spray were above some Canadian and international health protection guidelines. CONCLUSION: Although pesticide air concentrations measured in this study are generally consistent with other studies, maximum concentrations are greater than those that have been measured elsewhere, and some are above published air quality guidelines. An evaluation of the degree of risk posed by these and other pest control products to human and wildlife receptors is recommended. Copyright © 2009 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

A laboratory evaluation of the effectiveness of diflubenzuron against Dermestes maculatus De Geer and other storage insect pests

The chitin synthesis inhibitor diflubenzuron, applied as a wettable powder spray to woven polypropylene at 100–500 mg m^?2, was effective against Dermestes maculatus De Geer for at least 12 weeks. D. maculatus was unable to develop on ox hide dipped in a suspension of diflubenzuron (125 mg litre^?1), or on fishmeal dusted at 1–10 mg of active ingredient kg^?1. Diflubenzuron prevented the development of infestations of Callosobruchus maculatus (L.) on peas and of Acanthoscelides obtectus (Say) on beans dusted at 1–5 mg kg^?1. The compound was also very effective against early instar larvae of Trogoderma granarium Everts on wheat. The persistence and activity of diflubenzuron at low dosage rates against D. maculatus appear to justify larger scale trials.     

Surface contact toxicity and synergism of several insecticides against different stages of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae)

BACKGROUND: Five formulated insecticides (lambda‐cyhalothrin at 10 mg m^?2, bifenthrin at 50 mg m^?2, fipronil at 10 mg m^?2, fenitrothion at 50 mg m^?2, imidacloprid at 5 mg m^?2) and one active ingredient (DDT at 500 mg m^?2) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda‐cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed. RESULTS: The order of susceptibility of different stages of bed bugs was as follows: early stage ? lambda‐cyhalothrin > bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage—lambda‐cyhalothrin > bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult—lambda‐cyhalothrin > imidacloprid > bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT₅₀ among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects. CONCLUSIONS: Lambda‐cyhalothrin, bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus. Although imidacloprid demonstrated good initial response against C. hemipterus, the insects showed substantial recovery 72 h post‐treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation. Copyright © 2011 Society of Chemical Industry     

Propanil‐resistant barnyardgrass [Echinochloa crus‐galli (L.) Beauv.] in Sri Lanka: Seedling growth under different temperatures and control

Experiments were conducted to (i) evaluate the efficacy of propanil formulations available in Sri Lanka in controlling Echinochloa crus‐galli; (ii) study the seedling growth of propanil‐resistant (R) and ‐susceptible (S) biotypes of the weed under different temperatures; (iii) quantify the level of resistance in R biotypes and; (iv) to suggest alternative control measures for R biotypes. Field studies showed that retail propanil formulations (36% a.i., EC) applied at 2.7 kg a.i. ha^?1 gave less than 30% control of E. crus‐galli collected from several locations of the north dry zone of Sri Lanka. Chemical analysis revealed that there was no adulteration of propanil formulations at the retailer level. Growth studies conducted in controlled environments indicated that per cent germination and seedling growth of R and S biotypes were similar at the day/night temperature regimes imposed. However, per cent germination for plants grown under a 34/31°C (day/night) regime was 27–29% higher compared to those grown at 28/24°C. At the higher temperature regime, R and S biotypes reached the 2–3 leaf stage five days earlier, and the 4–5 leaf stage seven days earlier. The ED₅₀ values from the dose–response experiments indicated that the R biotype was four times more resistant to propanil than susceptible ones. The resistance index (RI) did not vary significantly under different temperature regimes. Quinclorac (25% a.i., SC) applied at 200 g a.i. ha^?1 and bispyribac‐sodium (10% a.i., SC) applied at 30 g a.i. ha^?1 (recommended dosages) successfully controlled propanil‐resistant biotypes of E. crus‐galli. Conversely, oxadiazon and propanil (8% and 23% a.i., EC, respectively) applied at 280 + 805 g a.i. ha^?1 did not result in satisfactory control.     

Organophosphorothioates and synergised synthetic pyrethroids as grain protectants on bulk wheat

Organophosphorothioates and synergised synthetic pyrethroids were used in duplicate field trials carried out on bulk wheat in commercial silos in Queensland and New South Wales. Laboratory bioassays using malathion-resistant strains of insects were carried out on samples of treated grain at intervals over 9 months. These established that all treatments were generally effective. Deltamethrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1), fenitrothion (12 mg kg^?1)+ fenvalerate (1 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1), fenitrothion (12 mg kg^?1)+ phenothrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) and pirimiphos-methyl (4 mg kg^?1)+ permethrin (1 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) controlled common field strains of Sitophilus oryzae (L.) and Rhyzopertha dominica (F.). Against a highly resistant strain of S. oryzae, deltamethrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) was superior to the remaining treatments. All treatment combinations completely prevented progeny production in Tribolium castaneum (Herbst), T. confusum Jacquelin du Val and in Ephestia cautella (Walker). Residues of deltamethrin, fenvalerate, permethrin and phenothrin were determined and shown to be highly persistent on stored wheat. During milling, residues accumulated in the bran fractions and were reduced in white flour. They were not significantly reduced during baking.     

Fate of carbendazim in rice tissues after seed or foliage treatments

Carbendazim was quantified employing reversed-phase high-performance liquid chromatography in rice coleoptiles, radicles and shoot portions of seedlings of different ages grown from seeds treated with the fungicide, and in shoot portions of adult plants at different times after foliar treatment with the fungicide. The highest levels of carbendazim were detected in the coleoptiles four days after germination of seeds and the radicals contained the lowest concentrations. Carbendazim residues declined with time in the shoot portions of seedlings and of adult plants. However, the levels of carbendazim detected in the shoot tissues of 21-day-old seedlings grown from treated seeds [recommended dose of 10 mg a.i. 10g^?1 seeds] and in adult plants 35 days after treatment (recommended dose of 0.25 g a.i. litre^?1 spray fluid) correspond to the reported lasting ability of the fungicide in terms of protection against blast of rice.     

Brodifacoum is effective against Norway rats (Rattus norvegicus) in a tyrosine139cysteine focus of anticoagulant resistance in Westphalia,Germany

BACKGROUND: The tyrosine to cysteine amino acid substitution at location 139 of the vkorc1 protein (i.e. tyrosine139cysteine or Y139C) is the most widespread anticoagulant resistance mutation in Norway rats (Rattus norvegicus Berk.) in Europe. Field trials were conducted to determine the incidence of the Y139C mutation at two rat‐infested farms in Westphalia, Germany, and to estimate the practical efficacy against them of applications, using a pulsed baiting treatment regime, of a proprietary bait (Klerat^?) containing 0.005% brodifacoum. RESULTS: DNA analysis for the Y139C mutation showed that resistant rats were prevalent at the two farms, with an incidence of 80.0 and 78.6% respectively. Applications of brodifacoum bait achieved results of 99.2 and 100.0% control at the two farms, when measured by census baiting, although the treatment was somewhat prolonged at one site, possibly owing to the abundance of attractive alternative food. CONCLUSION: The study showed that 0.005% brodifacoum bait is fully effective against Norway rats possessing the Y139C mutation at the Münsterland focus and is likely to be so elsewhere in Europe where this mutation is found. The pulsed baiting regime reduced to relatively low levels the quantity of bait required to control these two substantial resistant Norway rat infestations. Previous studies had shown much larger quantities of bromadiolone and difenacoum baits used in largely ineffective treatments against Y139C resistant rats in the Münsterland. These results should be considered when making decisions about the use of anticoagulants against resistant Norway rats and their potential environmental impacts. Copyright © 2012 Society of Chemical Industry