Insecticide Alpha-cypermethrin Research Articles

Novel transinfections of Rickettsiella do not affect insecticide tolerance in Myzus persicae, Rhopalosiphum padi, or Diuraphis noxia (Hemiptera: Aphididae).

Aphids (Hemiptera: Aphidoidea) are economically important crop pests worldwide. Because of growing issues with insecticide resistance and environmental contamination by insecticides, alternate methods are being explored to provide aphid control. Aphids contain endosymbiotic bacteria that affect host fitness and could be targeted as potential biocontrol agents, but such novel strategies should not impact the effectiveness of traditional chemical control. In this work, we used a novel endosymbiont transinfection to examine the impact of the endosymbiont Rickettsiella viridis on chemical tolerance in 3 important agricultural pest species of aphid: Myzus persicae (Sulzer) (Hemiptera: Aphididae), Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphididae), and Diuraphis noxia (Mordvilko ex Kurdjumov) (Hemiptera: Aphididae). We tested tolerance to the commonly used insecticides alpha-cypermethrin, bifenthrin, and pirimicarb using a leaf-dip bioassay. We found no observed effect of this novel endosymbiont transinfection on chemical tolerance, suggesting that the strain of Rickettsiella tested here could be used as a biocontrol agent without affecting sensitivity to insecticides. This may allow Rickettsiella transinfections to be used in combination with chemical applications for pest control. The impacts of other endosymbionts on insecticide tolerance should be considered, along with tests on multiple aphid clones with different inherent levels of chemical tolerance.

Proteomics Reveals Damaging Effect of Alpha-Cypermethrin Exposure in a Non-Target Freshwater Microalga Chlorella sp. NC-MKM

Alpha-cypermethrin, a pyrethroid pesticide, is frequently used on crops to prevent insect attacks. However, occasionally, due to drift, leaching, or with rainwater, it enters the aquatic environment and poses a serious threat to the growth of non-target aquatic organisms. In the current study, we were interested in investigating the damaging effect of alpha-cypermethrin on a local freshwater non-target green alga Chlorella sp. NC-MKM in terms of its protein levels. This was achieved by exposing Chlorella sp. NC-MKM to an EC50 concentration of alpha-cypermethrin for 1day, followed by the two-dimensional (2-D) gel electrophoresis and MALDI-TOF MS. Fifty-three proteins, which had showed significant differential accumulation (> 1.5 fold, P < 0.05) after exposure to alpha-cypermethrin, were considered as differentially accumulated proteins (DAPs). These DAPs were further divided into several functional categories, and the expressions of each in control and treatment samples were compared. Comparison revealed that alpha-cypermethrin exposure affects the accumulation of proteins related with photosynthesis, stress response, carbohydrate metabolism, signal transduction and transporters, translation, transcription, cell division, lipid metabolism, amino acid and nucleotide biosynthesis, secondary metabolites production, and post-translational modification, and thus rendered the tested algal isolate sensitive toward this pesticide. The overall findings of this research thus offer a fundamental understanding of the possible mechanism of action of the insecticide alpha-cypermethrin on the microalga Chlorella sp. NC-MKM and also suggest potential biomarkers for the investigation of pesticide exposed microalgae.

Effective control of Alphitobius diaperinus using natural bioinsecticides

Pest insects known as darkling beetles (Alphitobius diaperinus) are common in poultry farms. These pests can develop into a variety of disease vectors, causing damage to chicken coops, decreased chick performance, and financial losses to farmers. In Indonesia, synthetic insecticides are still used for pest control, which is detrimental to non-target creatures and the environment. The purpose of this study is to analyze the effectiveness of biopesticides from cinnamon bark extract (Cinnamomum aromaticum), nutmeg seeds (Myristica fragrans), lavender flowers (Lavandula angustifolia), and lime peel (Citrus aurantifolia), as well as synthetic insecticides alpha-cypermethrin against A. diaperinus larvae and imago. Bioinsecticide levels are 2.5%, 5%, 7.5%, and 10%, while alpha-cypermethrin levels are 1%, 4%, 7%, and 10%, respectively, based on LC50 values. The analysis was repeated three times and the treatment was carried out every two days for a total of 14 days. The data were analyzed with paired sample t-tests to determine the average difference in each treatment when there was an average difference and calculated N-Gain score to determine the effectiveness of biopesticides and synthetic insecticides. The average value of N-Gain essential oil from cinnamon bark extract was successful in causing A.diaperinus death in the imago stage (81.14) and the highest larvae (80) of other test solutions. Cinnamon bark extract and nutmeg seed extract are effective in imago (95.14) and larvae (78.91), respectively, and can be used as a natural biopesticide to replace synthetic insecticides in the control of A.diaperinus in imago and larvae stages. Keywords: Biological control, Biopesticides, Environmental management, Essential oils

Entomopathogenic fungus Metarhizium anisopliae (strain NCAIM 362) effects on soil inhabiting Melolontha melolontha (Coleoptera) and Duponchelia fovealis (Lepidoptera) larvae in sweet potato (Ipomoea batatas L.)

The functional role of the insect pathogen fungus Metarhizium anisopliae strain NCAIM 362 against the white grub cockchafer (Melolontha melolontha) larvae and southern European marshland pyralid (Duponchelia fovealis) larvae in a sweet potato cultivation was tested under greenhouse conditions. As a positive control, the effect of the same strain of M. anisopliae were compared with the effect of the synthetic insecticide alpha-cypermethrin. According to the results, alpha-cypermethrin was more effective against both the Coleoptera and Lepidoptera larvae, a lower number of surviving individuals as well as less damaged tubers were detected after the chemical treatment, compared with M. anisopliae.

Assessment of biochemical, hematological and behavioral biomarkers of Cyprinus carpio on exposure to a type-II pyrethroid insecticide Alpha-cypermethrin

This study assessed some important physiological biomarkers of freshwater edible fish Cyprinus carpio following exposure to 10 % (T1) and 20 % (T2) sublethal concentrations of Alpha-cypermethrin (A-cyp) over a total period of 45 days. Behavioral responses were noticed and Kaplan-Meier survival curves were prepared during acute toxicity study. Total serum protein concentration, total erythrocyte count, hemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and total leukocytes count were decreased significantly (p < 0.05), while the blood glucose, total serum lipid concentration, and clotting time were increased significantly (p < 0.05) over control. The most affected fish group and most significantly altered biomarker under toxic stress of A-cyp were identified using integrated biomarker response (IBR). The biomarker response index (BRI) values measured the overall health status of the treated fish and indicated that moderate adverse effects were exerted on the fish group exposed to T2 for 45 days.

Acetamiprid, chlorantraniliprole, and in some situations the physical barriers MultiPro® or Kvaae® wax, can be alternatives to traditional synthetic pyrethroid insecticides for the protection of young conifers from damage by the large pine weevil Hylobius abietis L.

ABSTRACT In UK forestry, the synthetic pyrethroid insecticides alpha-cypermethrin and cypermethrin have been used for many years to provide protection for young trees from damage by the large pine weevil, Hylobius abietis L. However, concerns over the toxicity of these insecticides has led to a search for alternatives. In our work, applications of 0.037 g.a.i.stem–1 acetamiprid provided high levels of protection from Hylobius browsing, comparable to alpha-cypermethrin or cypermethrin, and without causing phytotoxicity. However, re-application is likely to be required in the second growing season after planting. Our research identified that acetamiprid treated trees can be safely cold stored as part of normal nursery practice. Acetamiprid is less toxic than synthetic pyrethroids. We also found that pre-treating trees with 0.016 g.a.i.stem–1 chlorantraniliprole, a relatively low toxicity insecticide, can be equally effective in protecting trees, and that dye markers can be safely used to help target spays. Our testing of physical barriers such as MultiPro®, and to a lesser extent Kvaae® wax, suggests they may have a role as a partial substitute for the use of insecticides in some circumstances in the UK and Ireland, but only as part of an integrated approach where on-site populations of Hylobius are predicted to be low.

Are there viable chemical and non-chemical alternatives to the use of conventional insecticides for the protection of young trees from damage by the large pine weevil Hylobius abietis L. in UK forestry?

Abstract In UK forestry, the synthetic pyrethroid insecticides alpha-cypermethrin and cypermethrin have been used for many years to provide protection for young trees planted on restock sites from damage by the large pine weevil, Hylobius abietis L. However, concerns over the toxicity of these insecticides to aquatic life if misused have led to a search for alternative forms of protection. This paper describes a detailed programme of efficacy experiments undertaken between 2009 and 2015 to find replacements for these products. Over 50 combinations of chemical and non-chemical approaches were tested on 16 different sites. Of the alternative synthetic insecticides tested, applications of 0.037 g a.i. stem−1 acetamiprid provided high levels of protection from Hylobius browsing damage on young Sitka spruce (Picea sitchensis (Bong.) Carrière) trees, without causing any phytotoxic symptoms, and gave comparable levels of protection to those achievable using alpha-cypermethrin or cypermethrin. Acetamiprid is less toxic to aquatic life than alpha-cypermethrin or cypermethrin and has not been linked to bee decline. Applications of 0.0129 g a.i. stem−1 chlorantraniliprole also showed promise, and this relatively low toxicity non-neonicotinoid insecticide merits further study. Although imidacloprid and thiacloprid also provided good levels of protection, their use in forests is not now permitted due to concerns over their potential impacts on bees and drinking water, respectively. Whilst the natural product insecticide spinosad, and the entomopathogenic fungal control agent Metarhizium anisopliae (Metschn.) Sorokin, gave only limited protection in our work, they may have some future potential if methods of deployment can be improved. Other chemical and non-chemical approaches tested, but found to be largely ineffective in UK conditions, included the natural product insecticides azadirachtin, maltodextrin and pyrethrins, the synthetic insecticides lambda-cyhalothrin and spirotetramat and a wide range of repellents, flexible stem coatings and physical barrier products. However, we conclude that physical barrier sleeves such as MultiPro® and BioSleeve® may have a limited role as a partial substitute for the use of insecticides in the UK in some circumstances, but only if on-site populations of Hylobius are predicted to be low.

Non‐pesticide alternatives for reducing feeding damage caused by the large pine weevil (Hylobius abietis L.)

AbstractThe large pine weevil (Hylobius abietis L.) is an important pest of young forest stands in Europe. Larvae develop under the bark of freshly cut pine and spruce stumps, but maturing weevils feed on the bark of coniferous seedlings. Such seedlings frequently die because of bark consumption near the root collar. We tested the effect of three treatments (the insecticide alpha cypermethrin, a wax coating and a glue coating) on the feeding damage caused by H. abietis on Douglas fir (Pseudotsuga menziesii) and Norway spruce (Picea abies) seedlings under semi‐natural conditions. In two experiments (one in 2016 and another in 2017) seedlings in cages were subjected to pine weevil feeding for 16 weeks under shaded outdoor conditions. The experiment in 2016 compared insecticide and wax treatments and an untreated control on Douglas fir and Norway spruce, and the experiment in 2017 compared insecticide, wax and glue treatments and an untreated control on Norway spruce. In both experiments, all treatments significantly reduced H. abietis feeding damage at week 8 at the end of both experiments (week 16); the effect of treatments was significant only on spruce seedlings. The damages on Douglas fir seedlings was less on treated seedlings than on untreated control seedlings but differences were not significant. Coating stems with glue and especially with wax was generally effective at reducing weevil damage and in most cases provided control that was not significantly different from that provided by insecticide treatment. Our results suggest that a wax coating has the potential to replace the protection of seedlings provided by insecticides.

Susceptibility of phlebotomine sandflies (Diptera: Psychodidae) collected in the field, to alpha-cypermethrin in four municipalities endemic to leishmaniasis.

ABSTRACTAlthough the chemical control against leishmaniasis began in 1953 in Brazil, little information is available on how this strategy has affected populations of phlebotomine sandflies in the field. The objective of this study was to analyze the susceptibility profile of four populations of phlebotomine sandflies to the insecticide alpha-cypermethrin. Sandflies collected in field in four Brazilian municipalities were evaluated using CDC bottles in different concentrations of alpha-cypermethrin. A total of 1,186 phlebotomine sandflies were used in the bioassays. The LD50 ranged from 1.48 to 2.57 ug/mL in the field populations. For a dose of 5 ug/mL of alpha-cypermethrin, the LT50 and LT95 ranged from 17.9 to 27.5 minutes, and LT95 from 39.7 to 61.5 minutes, respectively. All the populations studied were highly susceptible to the insecticide alpha-cypermethrin. Routine studies are needed to detect changes in sandflies susceptibility to insecticides.

Timing of sub-lethal insecticide exposure determines parasite establishment success in an insect-helminth model.

Environmental toxicants are pervasive in nature, but sub-lethal effects on non-target organisms and their parasites are often overlooked. Particularly, studies on terrestrial hosts and their parasites exposed to agricultural toxicants are lacking. Here, we studied the effect of sequence and timing of sub-lethal exposures of the pyrethroid insecticide alpha-cypermethrin on parasite establishment using the tapeworm Hymenolepis diminuta and its intermediate insect host Tenebrio molitor as a model system. We exposed T. molitor to alpha-cypermethrin (LD20) before and after experimental H. diminuta infection and measured the establishment success of larval tapeworms. Also, we conducted in vitro studies quantifying the direct effect of the insecticide on parasite viability. Our results showed that there was no direct lethal effect of alpha-cypermethrin on H. diminuta cysticercoids at relevant concentrations (LD10 to LD90 of the intermediate host). However, we observed a significantly increased establishment of H. diminuta in beetles exposed to alpha-cypermethrin (LD20) after parasite infection. In contrast, parasite establishment was significantly lower in beetles exposed to the insecticide before parasite infection. Thus, our results indicate that environmental toxicants potentially impact host-parasite interactions in terrestrial systems, but that the outcome is context-dependent by enhancing or reducing parasite establishment depending on timing and sequence of exposure.

THE RESPONSE OF TWO VARITY OF FABA BEAN (AT FLOWERING STAGE) TO DIFFERENT CONCENTRATIONS OF ALPHA CYPERMETHRIN INSECTICIDE

The aim of the present study was to investigate the response of two types of form Faba bean Vicia faba L.(local and Italian), at flowering stage, to different concentration of insecticide alpha cypermethrin. Also, to study these effects on chlorophyll quantity and production of the plant. the experiment was designed according to the International Experimentation System (2x4) according to the Randomized complete Block Design (RCBD) with six replicates .The study involved two factors ; First one included two types of Faba bean (locally and Italian) , the second included different concentrations of the pesticide (distilled water, 0.05, 0.1, 0.2, mg/ml). The alpha cypermethrin pesticide lead to significant decreasing (P-value <0.05) in characteristic of chlorophyll A quantityand in crop yieldingplant height,pod number/plant, seeds number/pod, pod weight (g), pod length and the total weight for each 1000 grain. Which was with direct increase of the concentration. The Italian typerecorded a significant decrease in the chlorophyll A, plant height and pod weight comparing with the local type. it was obvious that the Italian type was more sensitive than the local type toward the pesticide and its negative effect is increasing with the increase of the concentration.

MACROPHYTE BIOASSAY APPLICATIONS FOR MONITORING PESTICIDES IN THE AQUATIC ENVIRONMENT

ABSTRACT The objective of this study was to evaluate the feasibility of the use of macrophytes Lemna minor and Azolla caroliniana as biomarkers of exposure (acute toxicity) for atrazine, bentazon + imazamox and clomazone, insecticide alpha cypermethrin + teflubenzuron and fungicides pyraclostrobin and mixture pyraclostrobin + epoxiconazole, as well as the risk for environmental intoxication. For this purpose, four plants of L. minor and five of A. caroliniana were selected in a 50 mL Hoagland medium. For both plants, the following concentrations were used: 0.10; 1.07; 3.44; 11.16; 36.40 and 118.0 mg L-1 of each test product and a control with three replicates. The results of this study demonstrated higher sensitivity of L. minor to the tested pesticides, when compared to A. caroliniana. L. minor can be used in the monitoring of herbicides bentazon, atrazine and clomazone and pyraclostrobin-based fungicide, and A. caroliniana can be used for pyraclostrobinbased fungicides, due to the sensitivity of these organisms when exposed.

Dissipation kinetics of alpha-cypermethrin and lambda-cyhalothrin residues in aboveground part of white mustard (Sinapis alba L.)

ABSTRACTDissipation of simultaneously applied insecticides alpha-cypermethrin and lambda-cyhalothrin was studied in a minor crop, aboveground part of white mustard (Sinapis alba L.). A validated gas chromatographic method (GC-ECD/NPD) was used to determine insecticide residues. Analytical performances were very satisfactory, with expanded uncertainties not higher than 14% (coverage factor k = 2, confidence level 95%). Dissipation of alpha-cypermethrin and lambda-cyhalothrin in white mustard followed first-order kinetics (R2 between 0.953 and 0.995), with half-lives of 3.1–4.6 and 2.9–3.7 days respectively. Based on the results of this two-year study and the relevant residue regulation, alpha-cypermethrin and lambda-cyhalothrin treatments can be considered safe for crop protection, feeding animals and the environment.

Low doses of the common alpha-cypermethrin insecticide affect behavioural thermoregulation of the non-targeted beneficial carabid beetle Platynus assimilis (Coleoptera: Carabidae)

Sub-lethal effects of pesticides on behavioural endpoints are poorly investigated in non-targeted beneficial carabids. Conspicuous changes in locomotor activity of carabids exposed to sub-lethal doses of neurotoxic insecticides suggest that many other behaviours of these insects might be severely injured as well. We hypothesize that behavioural thermoregulation of carabids may be affected by low doses of neurotoxic pyrethroid insecticide alpha-cypermethrin which may have direct deleterious consequences for the fitness and populations of the beetles in the field. Automated video tracking of the carabid beetle Platynus assimilis Paykull (Coleoptera: Carabidae) on an experimental thermal mosaic arena using EthoVision XT Version 9 software (Noldus Information Technology, Wageningen, The Netherlands) showed that brief exposure to alpha-cypermethrin at sub-lethal concentrations (0.1–10mgL−1) drastically reduces the ability of the beetles for behavioural thermoregulation. At noxious high temperature, a considerable number of the beetles died due to thermo-shock. Other intoxicated beetles that survived exposure to high temperature displayed behavioural abnormalities. During heating of the arena from 25 to 45°C, insecticide treated beetles showed a significant fall in tendency to hide in a cool shelter (20°C) and prolonged exposure to noxious high temperatures, accompanied by changes in locomotor activity. Next day after insecticide treatment the beetles recovered from behavioural abnormalities to a large extent but they still were considerably longer exposed to noxious high temperatures compared to the negative control beetles. Our results demonstrated that behavioural thermoregulation is a sensitive and important etho-toxicological biomarker in ground-dwelling carabids. Prolonged exposure to unfavourably high temperatures has an array of negative effects decreasing fitness and survival of these insects at elevated thermal conditions with deep temperature gradients, typical of agricultural habitats. These results may have importance in IPM programs promoting reduced insecticide use.

Behaviour of selected pesticide residues in blackcurrants ( Ribes nigrum) during technological processing monitored by liquid-chromatography tandem mass spectrometry

AbstractIn this experiment, the behaviour of ten pesticides on field-sprayed blackcurrants (Ribes nigrum) after washing, juicing and cooking was investigated. The concentration level changes in two acaricides (fenazaquin, propargite), three insecticides (alpha-cypermethrin, deltamethrin and lambdacyhalothrin) and five fungicides (boscalid, bupirimate, difenoconazole, pyraclostrobin, thiophanatemethyl) were quantified. Analysis was carried out using the QuEChERS method followed by chromatographic analysis based on LC-MS/MS. The matrix effects ranged from -(17.4 ± 8.1) % to (15.9 ± 7.8) %. The limits of detection and limits of quantification were 0.003 mg kg

Efficacy, Human Safety and Collateral Benefits of Alphacypermethrin Treated Long-Lasting Insecticidal Net (Interceptor®) in a Hyperendemic Tribal Area of Orissa, India

Interceptor net® is a long-lasting insecticidal net (LN) made of multifilament polyester fabric in which the insecticide alphacypermethrin is incorporated directly into the polymers at a dose of 200 mg/m2. This paper presents the results of an efficacy trial on Interceptor nets on malaria transmission in an area under the influence of pyrethroid susceptible vector species Anopheles culicifacies and A. fluviatilis in Sundargarh District, Orissa, India. There was a reduction of 57-76% in malaria incidence in Interceptor net area as compared to the control areas. Cross-sectional point prevalence surveys showed a reduction of 73.1% and 40% in malaria prevalence in Interceptor net and untreated net users respectively, whereas there was an increase of 17% in no net villages. The net usage rate in the study population was between 80-98% during different months. With respect to the adverse effects of the insecticide, people reported skin irritations but transitory in nature hence did not pose any danger. Interceptor nets also provided collateral benefits in terms of relief from other household pests such as head lice, bed bugs, cockroaches, ants and houseflies.

Effects of a triazole fungicide and a pyrethroid insecticide on the decomposition of leaves in the presence or absence of macroinvertebrate shredders

Previously, laboratory experiments have revealed that freely diluted azole fungicides potentiate the direct toxic effect of pyrethroid insecticides on Daphnia magna. More ecologically relevant exposure scenarios where pesticides are adsorbed have not been addressed. In this study we exposed beech leaves (Fagus sylvatica) to the azole fungicide propiconazole (50 or 500μgL−1), the pyrethroid insecticide alpha-cypermethrin (0.1 or 1μgL−1) or any combination of the two for 3h. Exposed leaves were transferred to aquaria with or without an assemblage of macroinvertebrate shredders, and we studied treatment effects on rates of microbial leaf decomposition, microbial biomass (using C:N ratio as a surrogate measure) and macroinvertebrate shredding activity during 26 days post-exposure. Microbial leaf decomposition rates were significantly reduced in the propiconazole treatments, and the reduction in microbial activity was significantly correlated with loss of microbial biomass (increased C:N ratio). Macroinvertebrate shredding activity was significantly reduced in the alpha-cypermethrin treatments. In addition, the macroinvertebrate assemblage responded to the propiconazole treatments by increasing their consumption of leaf litter with lower microbial biomass, probably to compensate for the reduced nutritional quality of this leaf litter. We found no interaction between the two pesticides on macroinvertebrate shredding activity, using Independent Action as a reference model. In terms of microbial leaf decomposition rates, however, alpha-cypermethrin acted as an antagonist on propiconazole. Based on these results we emphasise the importance of considering indirect effects of pesticides in the risk assessment of surface water ecosystems.

Evidence for a useful life of more than three years for a polyester-based long-lasting insecticidal mosquito net in Western Uganda

BackgroundLong-lasting insecticidal nets (LLIN) are now standard for the prevention of malaria. However, only products with recommendation for public use from the World Health Organization should be used and this evaluation includes the assessment of net effectiveness after three years of field use. Results for one of the polyester-based products, Interceptor® is presented.MethodsIn five villages, 190 LLIN and 90 nets conventionally treated with the insecticide alpha-cypermethrin at 25 mg/m2 were distributed randomly and used by the families. Following a baseline household survey a net survey was carried out every six months to capture use, washing habits and physical condition of the nets. Randomly selected nets were collected after 6, 12, 24, 36 and 42 months and tested for remaining insecticide content and ability to knock-down and kill malaria transmitting mosquitoes.ResultsDuring the three and a half years of observation only 16 nets were lost to follow-up resulting in an estimated attrition rate of 12% after three and 20/% after 3.5 years. Nets were used regularly and washed on average 1.5 times per year. After three and a half years 29% of the nets were still in good condition while 13% were seriously torn with no difference between the LLIN and control nets. The conventionally treated nets quickly lost insecticide and after 24 months only 7% of the original dose remained (1.6 mg/m2). Baseline median concentration of alpha-cypermethrin for LLIN was 194.5 mg/m2 or 97% of the target dose with between and within net variation of 11% and 4% respectively (relative standard deviation). On the LLIN 73.8 mg/m2 alpha-cypermethrin remained after three years of use and 56.2 mg/m2 after three and a half and 94% and 81% of the LLIN still had > 15 mg/m2 left respectively. Optimal effectiveness in bio-assays (≥95% 60 minute knock-down or ≥ 80% 24 hour mortality) was found in 83% of the sampled LLIN after three and 71% after three and a half years.ConclusionsUnder conditions in Western Uganda the tested long-lasting insecticidal net Interceptor® fulfilled the criteria for phase III of WHO evaluations and, based on preliminary criteria of the useful life, this product is estimated to last on average between three and four years.

Pesticide cocktails can interact synergistically on aquatic crustaceans

The ergosterol biosynthesis-inhibiting (EBI) fungicide prochloraz can enhance the effect of other pesticides in a range of animal species. Approximately 50% of the fungicides used in Denmark are EBI fungicides. Hence, if they all have synergising potential, a risk assessment of pesticide mixtures based on additivity might not suffice. This study investigates the synergising potential of six different EBI fungicides representing the imidazoles (prochloraz), the triazoles (epoxiconazole, propiconazole and tebuconazole), the piperidines (fenpropidin) and the morpholines (fenpropimorph) together with the pyrethroid insecticide alpha-cypermethrin. Tests were made on the aquatic crustacean Daphnia magna. Mixtures of each of the fungicides were tested together with the insecticide both at a 50:50% effect mixture ratio and, subsequently, in a ray design including five mixture ratios. The results were tested against the concentration addition reference model using dose-response surface analyses. The results of the binary dose-response surface studies showed that mixtures with prochloraz increased toxicity up to 12-fold compared with what was expected using the reference model concentration addition (CA). Epoxiconazole and propiconazole enhanced toxicity up to six and sevenfold, respectively. Fenpropimorph showed antagonism, whilst mixtures with tebuconazole and fenpropidin did not deviate statistically from CA. Hence, it can be concluded that both imidazoles and some, but not all, triazoles can enhance the effect of a pyrethroid insecticide towards D. magna substantially. Epoxiconazole and propiconazole are often sprayed out together with pyrethroids in tank mixtures. The extent to which this might create unforeseen ecological problems is discussed.

Efficacy of alphacypermethrin applied to cattle and sheep against the biting midge Culicoides nubeculosus

The recent emergence of bluetongue virus (BTV) in northern Europe, has led to an urgent need to identify methods to control the Culicoides biting midges that transmit it. Here, an in vitro assay was used to assess the effects of the proprietary pyrethroid insecticide alphacypermethrin applied to cattle and sheep (Dysect Cattle Pour-On, Dysect Sheep Pour-On; Ford Dodge Animal Health) against the biting midge Culicoides nubeculosus (Meigen) (Diptera: Ceratopogonidae). Hair or wool was collected from the back, belly and legs of animals immediately prior to treatment and 7, 14, 21, 28 and 35 days after treatment, and also from untreated controls. In the laboratory assay groups of 10 adult females C. nubeculosus were exposed to 0.5g of hair or wool for 3min. In all cases, no mortality was observed in the pre-treatment sample or the untreated controls. In the post-treatment samples, for both cattle and sheep mortality was close to 100% 7 days after treatment. For cattle, treatment effect persisted for up to 21 days post-treatment, following which the mortality rate following exposure to hair samples declined. In contrast, for sheep, mortality levels declined more slowly, and approximately 50% mortality was still observed 35 days after treatment. There was no significant difference in the kill rate for wool collected from the back, belly or legs of either sheep or cattle. The results demonstrate the potential for pour-on insecticide treatment to offer a degree of mitigation to livestock against onward transmission from infected animals—and in particular demonstrate that sufficient compound is able to reach the lower legs to kill in contact midges. The practical issues associated with achieving adequate protection are discussed.