Antifeeding effect of cypermethrin and permethrin at sub-lethal levels against Pieris brassicae larvae

An antifeeding (feeding deterrent) response by first- and fifth-instar larvae of Pieris brassicae was shown to be significant at sub-lethal levels of cypermethrin and permethrin, using leaf-discs treated with the pyrethroids by dipping. Permethrin was slightly more effective than cypermethrin both as an insecticide and as an antifeedant against fifth-instar larvae, but the reverse order of effectiveness was observed, with a marked difference in mortality, against newly-hatched larvae. When 1-day-old fifth-instar larvae were continuously given leaf discs treated with a solution of the pyrethroid (1 mg litre^?1), up to the time of pupation, both cypermethrin and permethrin induced a significant extension of the larval period, with a reduction in the maximum larval and pupal weights, as well as a reduction in the total leaf-area consumed. However, at higher levels of both pyrethroids, lowering the temperature induced some irritancy, as indicated by regurgitation and frequent uncoordinated wriggling movements of the fifth-instar larvae. The advantages of cypermethrin as a protectant and as an antifeedant over permethrin are discussed.     

Studies on the comparative effectiveness of permethrin and deet against bloodsucking arthropods

A comparison was made of the effectiveness of permethrin and deet against Ornithodoros parkeri (Acari: Argasidae), Leptotrombidium fletcheri (Acari: Trombiculidae), Rhodnius prolixus (Heteroptera: Reduviidae), Phlebotomus papatasi and Lutzomyia longipalpis (Diptera: Psychodidae), Anopheles Stephensi, Anopheles albimanus, Aedes taeniorhynchus, Aedes aegypti and Culex pipiens (Diptera: Culicidae), Glossina morsitans (Diptera: Glossinidae) and Xenopsylla cheopis (Siphonaptera: Pulicidae), using dose-response methods. At the ED₉₅ (95% effective dose) level, deet was more potent (P<0.05) than permethrin against all species except O. parkeri and R. prolixus. In addition, the slope of the dose-response line for deet was greater than that for permethrin against all species except O. parkeri and R. prolixus. Permethrin exhibited repellent and/or toxic effects, depending on the dose used and the individual tolerances of members of the insect test population.     

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.     

Cross-resistance to pyrethroids and other insecticides in Aedes aegypti

Two substrains of Aedes aegypti, already resistant to DDT and pyrethroids, were further selected using either DDT or permethrin by mass exposure of the females only. DDT selection over 14 generations raised the resistance to DDT so far that no accurate LC₅₀ values could be determined. Selection with permethrin raised the tolerance to an irregular plateau 7–10 times the original. DDT selection in the adults raised the DDT resistance of the larvae, but this could be partly overcome using a dehydrochlorinase inhibitor. The resistance to pyrethroids was increased but tolerance of dieldrin, malathion and propoxur compounds was little changed. Permethrin selection of the adults raised resistance to pyrethroids more than DDT selection but also increased DDT resistance. Similar patterns were found for the larval insects. A strain from Demerara in Guyana showed both DDT and pyrethroid resistance, including strong resistance to pyrethrins together with dieldrin and propoxur. It was concluded that two major independent resistance mechanisms existed in the selected strains, a dehydrochlorinase affecting DDT alone, and an unknown mechanism, probably nerve insensitivity (kdr) affecting both DDT and pyrethroids.     

Serial invasive signal amplification reaction for genotyping permethrin-resistant (kdr-like) human head lice, Pediculus capitis

Permethrin resistance in the human head louse, Pediculus capitis De Geer (Anopulura: Pediculidae), has been reported worldwide, is associated with the knockdown phenotype, and elicits cross-resistance to DDT and the pyrethrins. Two point mutations, T929I and L932F, in the voltage-sensitive sodium channel α-subunit gene are responsible for permethrin resistance as a resistant haplotype (kdr-like). We have optimized a serial invasive signal amplification reaction (SISAR) protocol for the detection of these mutations using PCR amplified DNA fragments. SISAR distinguished all genotypes with high accuracy in a head louse population from Texas that was heterogeneous in terms of permethrin sensitivity. Using SISAR, resistance-conferring mutations are detected in a high throughput format, facilitating the efficient monitoring of permethrin resistance allele frequency in field populations.     

A comparison of permethrin and methomyl insecticides for the control of a multiresistant strain of houseflies (Musca domestica)

A methomyl sugar bait formulation and permethrin residual spray were compared for the control of a multi-insecticide resistant strain of housefly in a UK pig farm. The methomyl was applied as a granular scatter bait at the manufacturer's recommended rate of 25 mg m^?2 active ingredient (a.i.) to the treated floor area. Permethrin was applied at 32, 64 and 128 mg m^?2 a.i. to structural surfaces. The highest deposit rate of permethrin used was four times that recommended by the manufacturer for the control of flying insects. The methomyl bait gave effective control but the permethrin spray failed at all deposit rates tested. The use of permethrin increased resistance to this compound at the KD50 level from x 13 to x 560 within 10 weeks and significantly increased the proportion of flies resistant to natural pyrethrins synergised with piperonyl butoxide (P<0.01).     

Neurophysiological studies of the effects of permethrin upon pyrethroid resistant (kdr) and susceptible strains of dipteran larvae

Permethrin at concentrations as high as 10^?6 had no detectable effect upon neuromuscular transmission at 20-21°C in the body-wall muscles of susceptible larvae of Lucilia sericata and susceptible and resistant (kdr) strains of larvae of Musca domestica. At the higher concentrations of 5 × 10^?6M, muscle cells in all strains and species of larva were slowly depolarised, resulting in failure of neuromuscular transmission when the level of depolarisation corresponded with the peak height of the postsynaptic potentials. Multiple postsynaptic potentials were sometimes obtained in response to a single electrical stimulus to the motor axon. Neither of these effects is considered to result from interference with release of the neurotransmitter or its binding to the postsynaptic receptors. Spontaneous activity in sensory nerve fibres from susceptible larvae was increased followed by intermittent bursting and block at concentrations of permethrin as low as 10^?9M at 20-21°C and 10^?10 at 26°C. Resistant larvae of M. domestica were 1000 times less sensitive, needing concentrations of permethrin as high as 10^?6M at 20-21°C and 10^?7M at 26°C to affect sensory discharge. The results are discussed in relationship to the cause of knockdown by pyrethroid insecticides and to possible changes in the nervous system which may be brought about by the kdr resistance factor.     

Toxicity of pyrethroids to larvae of the Egyptian cotton leafworm,Spodoptera littoralis (Boisd.). II. Factors determining the effectiveness of permethrin at ultra-low volume

Factors determining theeffectiveness of permethrinat ultra-low volume against larvae of Spodoptera littoralis (Boisd.) were investigated using a modified Potter tower. Higher mass application rates for 95 % control were necessary when permethrin was used as a residual deposit compared with direct contact plus residual deposit action. Mortality was increased by adjusting droplet density, although the optimum number of drops/ unit area depended on the mass application rate. When mass application rate and droplet density were held constant, mortality increased inversely with the mean droplet diameter. The implications of these results for field applications are discussed.     

The influence of spray droplet characteristics on the efficacy of permethrin against the diamondback moth Plutella xylostella: The effect of drop size and concentration on the potency of ulv- and ec-based residual deposits

The effect of droplet diameter (36-274 μm) and concentration (10-400 g litre^?1) of permethrin on the knockdown and mortality of 2nd-instar Plutella xylostella larvae was investigated. Larvae were placed on brussels sprout leaf discs treated with residual deposits of permethrin applied as ULV or emulsion formulations. The LD₅₀ of permethrin decreased with droplet size at all concentrations tested. This effect could not be accounted for solely by increased drop numbers per unit area of leaf, suggesting that for both formulations transfer of permethrin to larvae is more efficient for deposits composed of small drops. The concentration of permethrin in the ULV formulation could be reduced to approach a minimum quantity of toxicant per unit area to maintain 50 per cent mortality. The approach to the minimum dose varied with drop size and drop number per unit leaf area. The ULV formulation was approximately 2.7 times more effective at killing larvae than the emulsion, presumably as a result of greater availability of toxicant and transfer to larvae.     

Pyrethroid tolerance in Culex pipiens pipiens var molestus from Marin County, California

In May 2001 a sample of Culex pipiens pipiens variety molestus Forskål from Marin County, California, collected as larvae and reared to adults, was found to show reduced resmethrin and permethrin knock‐down responses in bottle bioassays relative to a standard susceptible Cx pipiens quinquefasciatus Say colony (CQ1). Larval susceptibility tests, using CQ1 as standard susceptible, indicated that the Marin mosquitoes had LC₅₀ resistance ratios of 18.3 for permethrin, 12 for deltamethrin and 3.3 for pyrethrum. A colony of Marin was established and rapidly developed higher levels of resistance in a few generations after exposure to permethrin as larvae. These selected larvae were shown to cross‐resist to lambda‐cyhalothrin as well as to DDT. However, adult knock‐down time in the presence of permethrin, resmethrin and pyrethrum was not increased after increase in tolerance to pyrethroids as larvae. Partial and almost complete reversion to susceptibility as larvae was achieved with S, S, S‐tributylphosphorotrithioate and piperonyl butoxide (PBO), respectively, suggesting the presence of carboxylesterase and P450 monooxygenase mediated resistance. Insensitive target site resistance (kdr) was also detected in some Marin mosquitoes by use of an existing PCR‐based diagnostic assay designed for Cx p pipiens L mosquitoes. Carboxylesterase mediated resistance was supported by use of newly synthesized novel pyrethroid‐selective substrates in activity assays. Bottle bioassays gave underestimates of the levels of tolerance to pyrethroids of Marin mosquitoes when compared with mortality rates in field trials using registered pyrethroid adulticides with and without PBO. This study represents the first report of resistance to pyrethroids in a feral population of a mosquito species in the USA. Copyright © 2003 Society of Chemical Industry     

Fate and short-term persistence of permethrin insecticide injected in a northern Ontario (Canada) headwater stream

1·275 dm³ of a l·3g dm^?3 aqueous emulsion of permethrin (i.e. 1·658 g permethrin) was applied to the surface of a fast-flowing stream by manual injection. Water samples were collected from the top 1-cm layer at different intervals of time at various distances downstream from the site of application. Caged samples of stream detritus, crayfish, brook trout and stonefly nymphs, bottled sediment and potted aquatic plants were placed 280 m from the treatment site, and collected afterwards for residue analysis. The downstream movement of the chemical was not uniform with peak concentrations of about 12 ng ml^?1 at 30 m and 0·1 ng ml^?1 at 730 m from the treatment site. The peak concentrations (ng g^?1) in potted aquatic plants, caged detritus, crayfish and brook trout were about 18, 39, 14 and 11 respectively. The residues were higher than the ambient water concentration (1·67 ng ml^?1) and dissipated slowly. The peak concentration in the bottled sediment was 2·75 ng g^?1, and the residues were lost rapidly. In contrast, the naturally occurring sediment in a beaver pond showed high residues that persisted for a longer period of time. Permethrin concentrations in invertebrate drift ranged from 9 to 357 ng g^?1, depending on the distance from the application site. The study demonstrated that aquatic invertebrates, plants and stream detritus acted as the major sink for the chemical.     

Microdroplet application for determination of comparative topical and residual efficacy of formulated permethrin to two populations of diamond back moth (plutella xylostella L.)

An on-demand, uniform droplet generator was used to apply 120 μm diameter drops of formulated permethrin either directly onto 3rd-instar Plutella xylostella, of two Ohio populations, or onto the abaxial surface of leaf discs (1-1000 drops cm^?2) to which those larvae were subsequently exposed. Incorporating a fluorescent tracer (Saturn Yellow GT-17N) in the spray mixture confirmed that ?direct hit”? larvae had received a topical dose from a single droplet. There was little difference in the LC₅₀/LD₅₀ for either population of P. xylostella when 24 and 48 h mortality assessments from direct hits were compared, but the LD₅₀ of Celeryville larvae was 6-8 times greater than that of Fremont larvae. Residual deposits of 120 μm drops containing approximately the LC₅₀, based on the topical assays, revealed that a droplet density providing a dose per cm² leaf surface of more than 1000 times the LD₅₀ was required to cause median mortality. The efficiency of utilisation, based on the topical LD₉₅ values, was 0.0006% and 0.072% for Fremont and Celeryville larvae, respectively.     

Sublethal effects of insecticides on the diamondback moth Plutella xylostella (L.)

The effect of sublethal concentrations (LC₁ and LC₅₀) of permethrin, fenvalerate, methamidophos and carbaryl on diamondback moth development, female fecundity and insect behaviour was investigated. All the insecticides had deleterious effects on the number of larvae surviving to pupae, the duration of the pupal period, the number of pupae surviving to adulthood, and cocoon formation in pupae. Prolonged duration of the larval period, from third instar to pupation, and deformed pupae were also observed. Permethrin, fenvalerate and carbaryl caused latent toxicity and deformed wings in the adults. Pyrethroids and methamidophos reduced the longevity of the adults whereas carbaryl increased it. Except for permethrin, the insecticides inhibited female fecundity. At LC₁ and LC₅₀ concentrations, the pyrethroids showed both repellent and antifeedant activity against larvae, and female moths preferred to oviposit on untreated leaf discs rather than on those treated with the pyrethroids at concentrations equal to their LC₅₀ values.     

Second International Symposium of the European Weed Research Society,Uppsala, August 1977

Abstract

The results of a discriminative spray application of decamethrin from a helicopter to fringing forest habitats of Glossina tachinoides in the Komoe valley, Upper Volta, are described. The insecticide formulated as a 2.5% emulsion concentrate was diluted with river water and applied from a Bell 47G-4A helicopter to the fringing forests of a 14 km long stretch of the River Komoe at a dosage of 12.5 g a.i./ha. The insecticide application equipment was so adjusted that when the helicopter was flown at 30 km/h, the effective swath width was about 30 m and the vmd of emitted spray was c.150 μm. Insecticide swaths were applied to the inner edges of fringing forests that were up to 100 m wide. Forests wider than 100 m received an additional insecticide swath.

The experimental area was protected from reinvasion by the establishment of dieldrin barriers at its extremities and along some tributaries and woodland/floodplain ecotones. The dieldrin was applied by the same method as was used to apply the decamethrin. The single discriminative application of decamethrin was extremely effective in controlling G. tachinoides for a period of at least 38 days, at the end of which time the wet season had commenced and there was evidence that flies were entering the experimental area from nearby unsprayed areas. The authors discuss the possible practical applications of the technique and make suggestions on how it might possibly be refined in order to reduce undesirable river water contamination and operational costs. The authors draw attention to the need for field trials, such as that reported upon, to be conducted on a sufficiently large scale and for the experimental areas to be well protected against reinvasion, if meaningful evaluation data are to be obtained.     

A new aqueous suspension concentrate formulation of cis‐permethrin and its insecticidal activity

Isomers of pyrethroids usually have different insecticidal activities. Permethrin, a non‐cyano pyrethroid, is not an exception and cis‐permethrin is much more active than the trans‐isomer against Triatoma infestans, vector of Chagas' Disease in Argentina. The large‐scale separation of cis‐ and trans‐permethrin was performed by successive recrystallizations from ethanol‐water mixtures. An aqueous suspension concentrate (flowable) formulation of pure crystalline cis‐permethrin was prepared and assayed for its insecticidal activity on wood and ceramic surfaces against nymph V of T infestans. This formulation was at least three times more effective than deltamethrin, with LC₅₀ values on ceramic of 0.11 µg cm⁻² and 0.33 µg cm⁻² respectively. On wood surfaces, the LC₅₀ value was 0.57 µg cm⁻² compared with 3.20 µg cm⁻² for deltamethrin. Against other insect species such as Periplaneta americana, Aedes aegypti and Culex quinquefasciatus, the suspension concentrate formulation of cis‐permethrin was, however, less effective than similar formulations of deltamethrin or β‐cypermethrin. © 2000 Society of Chemical Industry     

Acaricide resistance and synergism between permethrin and amitraz against susceptible and resistant strains of Boophilus microplus (Acari: Ixodidae)

The control of the southern cattle tick, Boophilus microplus (Canestrini), in Mexico and many other countries relies on chemical acaricides. Boophilus microplus has developed resistance to all major classes of acaricides in recent years. To gain a better understanding of the resistance and to develop resistance management strategies that benefit both Mexican ranchers and USDA's cattle fever tick eradication program (CFTEP), the authors used larval bioassay techniques to determine levels of resistance to permethrin and amitraz and then evaluated synergism between these two acaricides in one susceptible laboratory tick strain and four resistant strains originating from Mexico and Brazil. To examine mechanisms of resistance to permethrin in these strains, the frequency of a mutated sodium channel gene was determined using a PCR assay. The tick strains from Mexico and Brazil demonstrated 49.4- to over 672.2-fold resistance to permethrin, and up to 94.5-fold resistance to amitraz. While the San Roman strain from Mexico was the most permethrin-resistant strain, the Santa Luiza strain from Brazil was the most amitraz-resistant strain. A significant correlation was found between the permethrin resistance ratio and the allelic frequency of the sodium channel mutation. Significant synergism between permethrin and amitraz was found when one acaricide was tested in the presence of another. Synergism ratios ranged from 1.5 to 54.9 when amitraz was tested as a synergist for permethrin. Similar synergism ratios were obtained when permethrin was tested as a synergist for amitraz. Permethrin caused virtually no mortality in the San Roman strain, even at the highest concentration (3294 microg cm(-2)). Adding amitraz (11.0 microg cm(-2)) to permethrin led to a dramatic increase in larval mortality, even at very low concentrations of permethrin.     

The Experimental Application of Insecticides from a Helicopter for the Control of Riverine Populations of Glossina tachinoides in West Africa. VI. Observations on Side-Effects

Abstract

The experimental application by helicopter of six insecticides to riverine forest galleries of the Komoe River in Upper Volta against Glossina tachinoides Westw. was monitored for its effects upon non-target organisms, in particular birds, fish, insects and crustaceans inhabiting the experimental area. There was no recognisable mortality associated with applications of these insecticides on birds or fish. Aerosol applications of permethrin and decamethrin produced mortalities in two species of crustacea and very high mortalities occurred from a residual treatment of decamethrin at 12.5 g a.i./ha.     

Absorption and metabolism of permethrin and cypermethrin in the cockroach and the cotton-leafworm larvae

Permethrin was metabolised by attack at the ester bond, in vivo by adult cockroaches, Periplaneta americana and in vitro by esterase preparations. Metabolites retaining the ester linkage could not be detected. In all cases, the (1RS)-trans-isomer (transpermethrin) was more labile than the (1RS)-cis-isomer. Cypermethrin was metabolised at one-fifth the rate for permethrin. In-vitro and in-vivo studies with synergists indicated that cleavage of the ester bond in permethrin can be both oxidative for the (1RS)-cis-isomer and hydrolytic for the (1RS)-trans-isomer. The penetration of permethrin through the cuticle of the cockroach was significantly greater than that of cypermethrin. The penetration and metabolism of permethrin and cypermethrin in sixth-instar larvae of susceptible and resistant strains of the Egyptian cotton-leafworm, Spodoptera littoralis, were studied as possible factors in resistance. No significant differences were found. It is suggested that the major resistance factor to permethrin in S. littoralis is probably non-metabolic.     

Isolation of a Pseudomonas fluorescens metabolite/exotoxin active against both larvae and pupae of vector mosquitoes

A formulation was developed from the metabolite(s) of a novel Pseudomonas fluorescens Migula strain (VCRC B426) and tested against 4th-instar larvae and pupae of three species of vector mosquitoes, Anopheles stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti (L). The larvae and pupae of An. stephensi were the most susceptible to the formulation, followed by those of C. quinquefasciatus and Ae. aegypti, in that order, and the dosage requirement for pupal mortality was less than that required for larval mortality. The LC50 dosage requirements for larvae of these mosquito species were, respectively, 70.4, 511.5 and 757.3 microg protein ml(-1), whereas for pupae they were, respectively, 2.0, 9.4 and 19.2 microg protein ml(-1). The lethal fraction was purified from the culture broth and its molecular mass, as determined by high performance liquid chromatography, was 44kDa. This is the first report of a microbial formulation acting upon mosquito pupae, a non-feeding stage. Its mode of action and efficacy to control mosquitoes under field conditions need to be studied further.     

Control of tomato leafminer (Scrobipalpula absoluta) in Bolivia

Abstract

The leafminer Scrobipalpula absoluta Meyr. is a serious pest of tomatoes in the Los Valles region of the eastern foothills of the Bolivian Andes. An initial insecticide screening trial showed that the local population of S. absoluta had developed a high resistance to organophosphorous insecticides. Soil‐applied carbamates and Bacillus thuringiensis Berliner were also ineffective. Further trials were carried out to establish the optimum rates and timing of applications of two synthetic pyrethroids, fenvalerate and permethrin. The results showed that organophosphate‐resistant S. absoluta can be satisfactorily controlled under commercial growing conditions with tow doses of pyrethroid insecticides. Permethrin had greater toxicity and persistence than fenvalerate, and could be applied at longer intervals. It is recommended that permethrin, either as Ambush 50 e.c. at 100 ml/ha or as Pounce 30 e.c. at 170 ml/ha, be applied weekly or at 10–14‐day intervals at the beginning of the season or when infestations and damage are light.