Identification and transcriptional response of ATP-binding cassette transporters to beta-cypermethrin in the poultry red mite, Dermanyssus gallinae.

Dermanyssus gallinae, a worldwide pest in birds, has developed varying degrees of resistance to insecticides. The ATP-binding cassette (ABC) transporters are essential for the removal of xenobiotics from arthropods. However, our knowledge about ABC transporter proteins in D. gallinae is limited. Forty ABC transporters were identified in the transcriptome and genome of D. gallinae. The resistant population displayed an augmented metabolic rate for beta-cypermethrin compared to the susceptible group, with a remarkable increase in the content of ABC transporters. Verapamil was found able to increase the toxicity of beta-cypermethrin in the resistant population. Results from qRT-PCR analysis showed that eleven ABC transcripts were more highly expressed in the resistant population than the susceptible group at all stages of development, and beta-cypermethrin was observed to be able to induce the expression of DgABCA5, DgABCB4, DgABCD3, DgABCE1 and DgABCG5 in D. gallinae. RNAi-mediated knockdown of the five genes was observed to increase the susceptibility of resistant mites to beta-cypermethrin. These results suggest that ABC transporters, DgABCA5, DgABCB4, DgABCD3, DgABCE1 and DgABCG5 genes, may be related to beta-cypermethrin resistance in D. gallinae. This research will serve as a foundation for further studies on mechanism of insecticide resistance, which could be beneficial for controlling D. gallinae.

A novel spider venom peptide from the predatory mite Neoseiulus barkeri shows lethal effect on phytophagous pests.

The long-term use of pesticides in the field, and the high fertility and adaptability of phytophagous mites have led to resistance problems; consequently, novel safe and efficient active substances are necessary to broaden the tools of pest mite control. Natural enemies of arthropods typically secrete substances with paralytic or lethal effects on their prey, and those substances are a resource for future biopesticides. In this study, two putative venom peptide genes were identified in a parasitic mite Neoseiulus barkeri transcriptome. Recombinant venom NbSP2 peptide injected into Tetranychus cinnabarinus mites was significantly more lethal than recombinant NBSP1. NbSP2 was also lethal to Spodoptera litura when injected but not when fed to third instar larvae. The interaction proteins of NbSP2 in T. cinnabarinus and S. litura were identified by affinity chromatography. Among these proteins, ATP synthase subunit ß (ATP SSß) was deduced as a potential target. Four binding sites were predicted between NBSP2 and ATP SSß of T. cinnabarinus and S. litura. In conclusion, we identified a venom peptide with activity against T. cinnabarinus and S. litura. This study provides a novel component for development of a new biological pesticide.

Comparative sensitivity of Neoseiulus cucumeris and its prey Tetranychus cinnabarinus, after exposed to nineteen pesticides.

The toxicity tests of nineteen commonly used pesticides were carried out to compare the sensitivity differences between predatory mite Neoseiulus cucumeris and its prey Tetranychus cinnabarinus by a "leaf spray method" in laboratory microcosms. For two avermectins, emamectin benzoate and abamectin, exhibited high bioactivity against T. cinnabarinusf with LR50 values of 0.04 and 0.05 g a.i./ha, respectively, but these two insecticides showed the opposite toxic effects to N. cucumeris. These two agents showed strong selectivity for the two test species with Selective Toxicity Rate (STR) values of 950 and 620, respectively. However, for five neonicotinoids, the LR50s of dinotefuran, thiamethoxam, imidacloprid, and acetamiprid were all greater than the recommended rates in the field except for clothianidin, and they showed no obvious toxicity difference to the two species with STR values ranging from 0.58 to 2.00. For two organophosphates, malathion is more toxic to N. cucumeris than T. cinnabarinus, however, dimethoate showed a higher toxic effect on T. cinnabarinus. In addition, the toxicity of four pyrethroids, bifenthrin, deltamethrin, cyhalothrin and gamma-cyhalothrin to N. cucumeris was higher than that of T. cinnabarinus, except for alpha-cypermethrin. For five acaricides, spirodiclofen, spirotetramat and pyridaben had no obvious selectivity to the two organisms, while diafenthiuron and chlorfenapyr were found to be highly toxic to T. cinnabarinus than N. cucumeris with STR values of 14.2 and 68.5, respectively. Thus, some pesticides above-mentioned like emamectin benzoate, abamectin, diafenthiuron and chlorfenapyr exhibited potential to be used in the management programs of T. cinnabarinus, especially in organically based production systems where there are fewer chemical control measures available, which need to combine with natural enemies to achieve the best control effect.

Bacillus lipopeptides as powerful pest control agents for a more sustainable and healthy agriculture: recent studies and innovations.

MAIN CONCLUSION: Lipopeptides could help to overcome a large concern in agriculture: resistance against chemical pesticides. These molecules have activity against various phytopathogens and a potential to be transformed by genetic engineering. The exponential rise of pest resistances to different chemical pesticides and the global appeal of consumers for a sustainable agriculture and healthy nutrition have led to the search of new solutions for pest control. Furthermore, new laws require a different stance of producers. Based on that, bacteria of the genus Bacillus present a great agricultural potential, producing lipopeptides (LPs) that have high activity against insects, mites, nematodes, and/or phytopathogens that are harmful to plant cultures. Biopesticide activity can be found mainly in three families of Bacillus lipopeptides: surfactin, iturin, and fengycin. These molecules have an amphiphilic nature, interfering with biological membrane structures. Their antimicrobial properties include activity against bacteria, fungi, oomycetes, and viruses. Recent studies also highlight the ability of these compounds to stimulate defense mechanisms of plants and biofilm formation, which is a key factor for the successful colonization of biocontrol organisms. The use of molecular biology has also recently been researched for continuous advances and discoveries of new LPs, avoiding possible future problems of resistance against these molecules. As a consequence of the properties and possibilities of LPs, numerous studies and developments as well as the attention of large companies in the field is expected in the near future.

Mode of entry of secondary metabolites of the bacteria Xenorhabdus szentirmaii and X. nematophila into Tetranychus urticae, and their toxicity to the predatory mites Phytoseiulus persimilis and Neoseiulus californicus.

The bacterial metabolites in supernatants of Xenorhabdus species have acaricidal activity, but this mode of entry into mites has not yet been elucidated. Herein, we report on the possible mode of entry of Xenorhabdus szentirmaii and Xenorhabdus nematophila supernatants into Tetranychus urticae (Acari: Tetranychidae) adult females. We also assessed the toxicity of the supernatants against the developmental stages of the predatory mites, Phytoseiulus persimilis and Neoseiulus californicus (Acari: Phytoseiidae). Experiments were conducted at 25 ± 1 °C, 70 ± 5% relative humidity, and 16:8h light:dark conditions. Our data showed that the bioactive acaricidal compound is most effective (86.5 to 89% mortality) when the entire integument of T. urticae comes in contact with it compared to contact of the ventral side only (26.5-34%). Against P. persimilis and N. californicus at 6 days post-application (dpa), the eggs were not affected by the X. szentirmaii or X. nematophila supernatant, whereas mortality of the mobile stages (larva, protonymph, deutonymph, adult) was 18.5% to 39.2%. Overall, the predatory mites were less affected by the bacterial metabolites than T. urticae. We hypothesize that the differences in morphology such as longer legs and thicker cuticle, as well as the diet of the predatory mites, reduce the contact of the body parts to the supernatant-treated surfaces. We need to isolate, identify, and characterize the X. szentirmaii and X. nematophila metabolite(s) and demonstrate efficacy to pestiferous mites and safety to plants, non-target organisms and the environment before it can be used as an acaricide.

Resistance to pyridaben in Canadian greenhouse populations of two-spotted spider mites, Tetranychus urticae (Koch).

Two-spotted spider mite (TSSM) Tetranychus urticae (Koch) is an important agricultural pest that causes considerable yield losses to over 150 field and greenhouse crops. Mitochondrial electron transport inhibitors (METI) acaricides are commonly used to control mite species in commercial Canadian greenhouses. Development of resistance to METIs in TSSM populations have been reported worldwide, but not until recently in Canada. The objectives of this study were to: 1) monitor the acaricide-susceptibility in greenhouse TSSM populations, and 2) investigate the resistance to pyridaben, a METI acaricide, in greenhouse resistant and pyridaben-selected (SRS) mite strains. The increased mortality to the pyridaben sub-lethal concentration (LC30) when SRS mites were exposed to piperonyl butoxide (PBO), a general cytochrome P450 monooxygenase inhibitor, and higher P450 activity compared to the greenhouse strain (RS) mites, indicated that P450s may be at least partially responsible for the resistance. The molecular mechanisms of target site insensitivity-mediated resistance in the pyridaben resistant strain of TSSM were investigated by comparing the DNA sequence of NADH dehydrogenase subunits TYKY and PSST, NADH-ubiquinone oxidoreductase chain 1 and 5 (ND1, ND5) and the NADH-ubiquinone oxidoreductase subunit 49 kDa from SRS to the reference strain (SS) and RS. Despite a number of nucleotide substitutions, none correlated with the pyridaben resistance. Understanding the underlying mechanisms of TSSM adaptation to acaricides is an essential part of resistance management strategy in any IPM program. The findings of this study will encourage growers to apply acaricides with different modes of action to reduce the rate at which acaricide resistance will occur in greenhouse TSSM populations.

Diagnosis and treatment of demodicosis in dogs and cats: Clinical consensus guidelines of the World Association for Veterinary Dermatology.

BACKGROUND: Demodicosis is a common disease in small animal veterinary practice worldwide with a variety of diagnostic and therapeutic options. OBJECTIVES: To provide consensus recommendations on the diagnosis, prevention and treatment of demodicosis in dogs and cats. METHODS AND MATERIALS: The authors served as a Guideline Panel (GP) and reviewed the literature available before December 2018. The GP prepared a detailed literature review and made recommendations on selected topics. A draft of the document was presented at the North American Veterinary Dermatology Forum in Maui, HI, USA (May 2018) and at the European Veterinary Dermatology Congress in Dubrovnik, Croatia (September 2018) and was made available via the World Wide Web to the member organizations of the World Association for Veterinary Dermatology for a period of three months. Comments were solicited and responses were incorporated into the final document. CONCLUSIONS: In young dogs with generalized demodicosis, genetic and immunological factors seem to play a role in the pathogenesis and affected dogs should not be bred. In old dogs and cats, underlying immunosuppressive conditions contributing to demodicosis should be explored. Deep skin scrapings are the diagnostic gold standard for demodicosis, but trichograms and tape squeeze preparations may also be useful under certain circumstances. Amitraz, macrocyclic lactones and more recently isoxazolines have all demonstrated good efficacy in the treatment of canine demodicosis. Therapeutic selection should be guided by local drug legislation, drug availability and individual case parameters. Evidence for successful treatment of feline demodicosis is strongest for lime sulfur dips and amitraz baths.

Ecotoxicological assessment after the world's largest tailing dam collapse (Fundão dam, Mariana, Brazil): effects on oribatid mites.

Worldwide, environmental tragedies involving mining dam ruptures have become more frequent. As occurred a few years ago in Brazil (on 5 November 2015, in Minas Gerais state) the Fundão Dam rupture released 60 million m3 of tailings into terrestrial and aquatic ecosystems. Since then, little information on the ecotoxicity of these tailings has been disclosed. In the laboratory, the acute, chronic and bioaccumulation effects of increased Fundão tailing concentrations on oribatid mites (Scheloribates praeincisus) were assessed. Additionally, the bioaccumulation of 11 trace metals (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) and the total density of oribatid mites found in the areas contaminated by the Fundão tailings were determined. The percentages of mite survival and reproductive inhibition were higher than 60% and 80%, respectively, in all contaminated areas with the highest concentration (100% mine tailings). Field studies showed an expressive reduction in the total density of oribatids per m-2 (up to 54 times) in the contaminated areas compared with the reference area. Metal accumulations in the field were 5.4 and 3.2 higher (for Ni and Hg, respectively) and up to two times higher (for most metals) than those in the laboratory for 42 days. The mite responses to the Fundão tailings found in this study suggest long-term interference in their biological development. In this sense, we can conclude that the introduction of mine tailings onto soils tended to compromise the functionality of the mites in the ecosystem, which causes imbalances to cascade other organisms of the trophic web.

Efficacy of λ-cyhalothrin, amitraz, and phoxim against the poultry red mite Dermanyssus gallinae De Geer, 1778 (Mesostigmata: Dermanyssidae): an eight-year survey.

Dermanyssus gallinae (De Geer, 1778) is a major problem for the poultry industry worldwide, as it negatively affects virtually all kinds of rearing systems. Therefore, the control of infestation has become a routine process, and its economic cost is constantly increasing. Until now, most of the control strategies have relied on the use of synthetic chemical drugs, but their efficacy is often questioned by the emergence and diffusion of resistant mite populations. With this in mind, the efficacy of λ-cyhalothrin, amitraz, and phoxim has been verified by testing them against 86 mite populations collected from the same number of poultry farms in Italy from 2008 to 2015. Assays were performed according to the filter paper method using the recommended, half, quarter, double and quadruple doses. The results showed that phoxim and amitraz were the most effective acaricides (median efficacies 80.35% and 80.83%, respectively), but amitraz exhibited a sharp fall in its efficacy during 2011 and 2012, while phoxim maintained its high effectiveness up to 2015, when it dropped. The overall median efficacy of λ-cyhalothrin was 58.33%. The data also highlighted the importance of the use of the right concentration, as an increase in dosage was not always useful against resistant populations, while its reduction also diminished efficacy, simultaneously increasing the risk for the development of resistance.

Critically appraised topic for the most effective and safe treatment for canine generalised demodicosis.

BACKGROUND: Canine generalised demodicosis is an inflammatory parasitic skin disease caused by an excessive proliferation of Demodex spp. Generalized demodicosis is a severe skin disease, that can be life threatening if not treated properly. Many of the current treatment options are not licensed for the treatment of generalised demodicosis, it have a low safety margin and may be poorly efficacious and time-consuming for the owner; there is a need for a safe, efficacious treatment for canine demodicosis. Our objective was to systematically review the literature to determine the most effective and safe topical or systemic therapy for canine generalised demodicosis. Single case reports and case series with fewer than five patients were not reviewed as they were considered to be poor quality evidence. A detailed literature search identified 21 relevant clinical trials and these were critically assessed. RESULTS: The analysis of the best available evidence on March 5, 2018, suggests that six are the most effective and safe treatments for generalised canine demodicosis including (in alphabetical order): doramectin (oral or parenteral); fluralaner (oral); imidacloprid/moxidectin (topical); ivermectin (oral, not as first choice treatment); milbemycin oxime (oral); and sarolaner (oral). There was insufficient evidence to allow comment on the appropriateness of other treatment protocols for canine generalised demodicosis in this CAT. CONCLUSIONS: In our critical appraisal of the best scientific literature, there is evidence for recommending the use of 6 therapeutic options against demodectic mange. Further, in vivo, controlled, randomized and blinded clinical trials are required, to evaluate new therapies.

Bioactivity of an oxymatrine-based commercial formulation against Brevipalpus yothersi Baker and its effects on predatory mites in citrus groves.

The acaricidal bioactivity of an oxymatrine-based commercial formulation against Brevipalpus yothersi Baker (Acari: Tenuipalpidae), a vector mite of the Citrus leprosis virus (CiLV), and its impact on predatory mites were assessed. For this purpose, laboratory and field assays using bioacaricide concentrations ranging from 0.5 to 2.0 mg L-1 of oxymatrine were performed during the years from 2015 to 2016. Laboratory results showed that the oxymatrine-based commercial formulation does not cause deleterious effects on B. yothersi eggs; however, it causes high larval mortality. For adult females, the bioacaricide caused high acute toxicity and residual effect for at least 5 days after application. In the field, the bioacaricide exhibited high acaricidal activity against B. yothersi, with efficacy levels similar to that of synthetic acaricide spirodiclofen (48 mg L-1) until 49 days after the application. The application of the bioacaricide did not negatively affect the population levels of phytoseiid predatory mites. Therefore, our results suggest that the oxymatrine-based commercial formulation is an important tool for management of the citrus leprosis mite in citrus groves.

Pyrethroid resistance in the pest mite, Halotydeus destructor: Dominance patterns and a new method for resistance screening.

An L1024F substitution in the para gene, which encodes a subunit of the voltage-gated sodium channel, has been implicated in pyrethroid resistance in a mite pest, Halotydeus destructor, which attacks rape and other grain crops. A high-resolution melt (HRM) genotyping assay was developed for testing the relative pyrethroid susceptibility of different para genotypes and for high-throughput field screening of resistant alleles. The L1024F mutation was found to be incompletely recessive in phenotypic laboratory bioassays with the pyrethroid pesticide, bifenthrin. While the resistance ratio of heterozygotes (RS) to susceptible homozygotes (SS) was <6 in 24 h bioassays, the resistant homozygotes (RR) (with a resistance ratio > 200,000) survived the recommended field rate of bifenthrin (100 mgL-1). HRM genotyping of mites from field populations across Australia indicated the presence of resistant alleles in Western Australia and South Australia, but not in Victoria and New South Wales. The assay developed will be useful for routine screening of pyrethroid resistance, and the dominance relationships established here point to useful resistance management strategies involving the maintenance of reservoirs of susceptible mites to dilute resistant homozygotes in a population.

The response of three species of phytoseiid mite (Acari: Phytoseiidae) to synthetic pyrethroid pesticides in the laboratory and the field.

The Kanzawa spider mite, Tetranychus kanzawai Kishida, is a major pest in tea fields [Camellia sinensis (L.) O. Kuntze] in Japan. However, recently, there have been some instances where acaricides are no longer applied as a result of the low occurrence of T. kanzawai in tea fields in Japan. In the period of 2015-2017, surveys of predatory mites in the study tea field detected Amblyseius eharai Amitai and Swirski, Phytoseiulus persimilis Athias-Henriot, Euseius sojaensis (Ehara), Amblyseius obtuserellus Wainstein and Begljarov, and Typhlodromus vulgaris Ehara in tea fields, but not Neoseiulus womersleyi (Schicha), indicating that a major change in the composition of the phytoseiid mite population had occurred. In laboratory studies, we confirmed the ability to avoid synthetic pyrethroid insecticides of the major beneficial mites in tea fields, A. eharai and P. persimilis, but not of E. sojaensis, a predatory mite whose population declined heavily after pesticide application. Attempts are made in this study to associate the decrease in T. kanzawai frequency in Japan with changes in pesticide used, method of spraying, and composition of the phytoseiid mite population. By continuing the method of pesticide spraying ('partial surface'), which leaves refugia in the leaf layer with sub-lethal dosages of pesticide, phytoseiid mites are aided to evade pesticides, resulting in maintenance of the composition of the phytoseiid mite populations in terms of diversity and abundance. Maintaining the diversity and abundance of Phytoseiidae may have contributed to the stabilization of the T. kanzawai population at low densities in Japanese tea fields.

Ketalization of 2-heptanone to prolong its activity as mite repellant for the protection of honey bees.

BACKGROUND: 2-Heptanone is a volatile liquid known to be effective in protecting honey bees from parasitic mite infestations in hives. The present study aimed to show that chemical derivatives of 2-heptanone would release the ketone for a significantly longer time than it takes for the pure ketone to evaporate and preferably for as long as two brood cycles of a honey bee (42 days). RESULTS: A liquid ketal of 2-heptanone with glycerol (Glyc-Ket) and solid ketals of the ketone with polyvinyl alcohol (PVAl-Ket), containing different amounts of the ketone, were synthesized. The fully resolved 1 H and 13 C nuclear magenetic resonance (NMR) spectra of the ketals are discussed. In the case of the polymer, differential scanning calorimetry (DSC) of a ketal was also compared with the unketalized polyvinyl alcohol. The length of time for which 2-heptanone was released by the ketals was determined by gas chromatography-mass spectrometry of the headspace. In the case of Glyc-Ket, the concentration of the 2-heptanone in the liquid phase was also monitored by 1 H NMR spectroscopy. The deketalization was pH dependent, ranging between 2.0 and 2.5 for Glyc-Ket and between 2.0 and 3.5 for PVAl-Ket. CONCLUSION: Under bee hive conditions, the release of 55 mmol 2-heptanone from Glyc-Ket lasted for 42 days, whereas the release of the ketone from the PVAl-Ket with a similar amount of the ketone lasted for 23 days, versus a maximum of 17 days for an equivalent amount of the pure ketone. These ketals therefore have the potential to be effective mite repellants for the protection of honey bees. © 2019 Society of Chemical Industry.

Increase of scabies in Germany and development of resistant mites? Evidence and consequences.

Scabies has been diagnosed surprisingly frequently in Germany in recent years, and the use of acaricides has risen markedly. Present figures indicate an increase in the prevalence/incidence of scabies, but do not prove or quantify it for the following reasons: (a) scabies is not a notifiable disease in Germany; (b) the diagnosis is not always confirmed lege artis by means of light microscopy or dermatoscopy (which may lead to a comparatively high proportion of false­positive diagnoses due to the low overall prevalence of scabies); (c) repeated treatments of the same patient and treatment of contact persons are included in the total number of prescriptions. Therefore, there are no valid data on disease occurrence, either in the current situation or from previous periods. Observations of ineffective treatment with permethrin have led to speculations that Sarcoptes mites are developing resistance to this drug. However, there is little evidence for this assumption. We discuss risk groups (children, elderly people in need of care, migrant health personnel in nursing institutions, refugees, sexually active young adults) and evaluate their possible contribution, albeit in the absence of evidence. None of the groups would be solely responsible for an increased frequency. We have compiled recommendations on how the management of scabies could be improved, and present a way of differentiating permethrin resistance from application errors and/or lack of compliance. The goal is to solve the epidemiological and parasitological questions mentioned above.

Toxicity of six insecticides to predatory mite Amblyseius cucumeris (Oudemans) (Acari: Phytoseiidae) in- and off-field.

Amblyseius cucumeris (Oudemans) is a beneficial non-target arthropod (NTA) and a key predator of tetranychid mites in integrated pest management (IPM) programs across China. Evaluating the toxic effects of insecticides on such predatory mites is essential for the success and development of IPM. We tested six insecticides to determine the risk of neonicotinoid insecticide toxicity to predatory mites, using the 'open glass plate method' and adult female A. cucumeris in a "worst case laboratory exposure" scenario. A 48-h toxicity test was performed using the hazard quotient (HQ) approach to evaluate the risk of each insecticide. The LR50 values (application rate that caused 50% mortality) of acetamiprid, thiamethoxam, imidacloprid, and dinotefuran were 76.4, 104.5, 84.9, and 224.6 g active ingredient (a.i.) ha-1, respectively, with in-field HQ values of 0.40, 1.28, 0.49, and 0.82, respectively. The HQ values were lower than the trigger value of 2, and were consistent with off-field values. The risks of the four neonicotinoid insecticides to adult female A. cucumeris were acceptable in two exposure scenarios in field and off field. The 48-h LR50 values for bifenthrin and malathion were 0.008 and 0.062 g. a.i. ha-1, respectively, which were much lower than the recommended field application rates. The HQ values were much higher than the trigger values for both in- and off-field, indicating that the risks of these two insecticides were unacceptable. Bifenthrin and malathion posed an extremely high risk to the test species, and their use should be restricted to reduce risks to the field with augmentative releases of A. cucumeris.

Status of pesticide resistance and associated mutations in the two-spotted spider mite, Tetranychus urticae, in China.

The two-spotted spider mite, Tetranychus urticae Koch, is a serious agricultural pest that has developed resistance to many pesticides. A leaf dip assay was used to assess the resistance of seven field populations of T. urticae to 11 pesticides in China. The mutation frequencies of target genes related to pesticide resistance were also determined. The results showed that all seven field populations had high or extremely high resistance to abamectin and had low or moderate resistance to newly developed pesticides including bifenazate, cyenopyrafen, chlorfenapyr, B-azolemiteacrylic, and spinetoram. The RF values for the traditional acaricides bifenthrin, pyridaben, and profenofos were low for all seven populations. For target sites related to abamectin resistance, the frequency of the mutations ranged from 28.33 to 63.64% for G314D in the glutamate-gated chloride channel gene 1 (GluCl1), and from 0 to 95% for G326E in the glutamate-gated chloride channel gene 3 (GluCl3). For target sites related to organophosphate resistance, the frequency of mutations ranged from 33.33 to 56.67% for G119S and from 5.00 to 43.33% for A201S in the acetycholinesterase gene (Ace). For target sites related to pyrethroid resistance, the frequency of the mutations ranged from 76.67 to 98.33% for A1215D and from 3.33 to 100% for F1538I in the voltage-gated sodium channel gene (VGSC). No mutations were detected in the bifenazate resistance-related cytochrome b gene (Cytb). These results will be useful for managing T. urticae resistance to pesticides in China.

A field trial in Thailand of the efficacy of oral fluralaner for the treatment of dogs with generalized demodicosis.

BACKGROUND: Generalized demodicosis in dogs can be challenging to manage, especially in adult-onset cases. HYPOTHESIS/OBJECTIVES: This study evaluated the efficacy of oral fluralaner at the dose of 25-50 mg/kg for the treatment of canine generalized demodicosis. ANIMALS: Client-owned dogs from Bangkok, Thailand, diagnosed with generalized demodicosis according to published criteria. METHODS: Deep skin scrapings were performed at three to five affected areas to evaluate numbers of mites. Repeat examinations were performed monthly until parasitological cure; dogs were then followed up for two to 12 months. Parasitological cure was defined as two negative skin scrapings achieved one month apart. RESULTS: One hundred and fifteen dogs were included in the study, 73 with adult-onset demodicosis and 42 with juvenile-onset demodicosis. Twenty one dogs were lost to follow-up and 27 had one negative skin scraping but did not return. Sixty seven dogs (21 with juvenile-onset and 46 with adult-onset disease) reached parasitological cure, which occurred after two, three and four months in 63%, 85% and 100% (respectively) of dogs with adult-onset demodicosis, cumulatively, and after two and three months in 81% and 100% of dogs with juvenile-onset demodicosis. Underlying causes associated with adult-onset demodicosis included atopic dermatitis, neoplasia, metabolic diseases and idiopathy. No adverse effects of fluralaner were observed in any of the dogs. CONCLUSION: Fluralaner given at the label dose for flea and tick prevention is effective for the treatment of canine generalized demodicosis.

Genetic variability and pyrethroid susceptibility of the parasitic honey bee mite Varroa destructor (Acari: Varroidae) in Iran.

The ectoparasitic honey bee mite Varroa destructor Anderson & Trueman (Acari: Varroidae) is one of the major concerns for worldwide beekeeping. The use of synthetic pyrethroids for controlling the mite was among the most popular treatments until resistance evolved in the mid 1990's. In Iran, beekeepers are dealing with the parasite and they also used pyrethroids for controlling the mite for a long time. After the evolution of resistance to pyrethroids, they based mite control mostly on treatments with amitraz, organic acids and several management practices. Here we conducted a comprehensive characterization of V. destructor populations parasitizing Apis mellifera in Iran. We determined the genetic variability of mites collected from 28 localities distributed throughout the country. The haplotype of V. destructor was determined by PCR-RFLP, analyzing a fragment of the mitochondrial cox1 gene. It was found that only the Korean haplotype was present in samples from all localities. DNA fragments from cox1, atp6, cox3 and cytb mitochondrial genes were sequenced and the results showed that all samples were identical to the K1-1 or the K1-2 V. destructor haplotypes. Moreover, as it has been reported that resistance to pyrethroids in V. destructor is associated with mutations at position 925 of the voltage-gated sodium channel, a TaqMan®-based allelic discrimination assay was conducted to genotype the mites collected. The results showed that all the mites tested were homozygous for the wild-type allele and, therefore, susceptible to treatment with pyrethroids.

Acaricidal and repellent effects of Cnidium officinale-derived material against Dermanyssus gallinae (Acari: Dermanyssidae).

The acaricidal activity of a methanolic extract and fractions from the rhizome of Cnidium officinale against Dermanyssus gallinae adults was investigated. The C. officinale methanolic extract exhibited 100% acaricidal activity after 48 h of treatment at a dose of 4000 ppm. The acaricidal constituents of the plant were sequentially partitioned with several solvents and then purified using silica gel column chromatography and high-performance liquid chromatography. Gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy revealed (Z)-ligustilide as a constituent of C. officinale. Acaricidal activity was examined in three experimental tests (spray, fumigation and contact), with the spraying method being the most effective. The methanolic extract of C. officinale showed both contact and fumigant activities, though only fumigant activity was observed with (Z)-ligustilide. The fumigant effects of the methanolic extract and (Z)-ligustilide caused 86.5 and 62.6% mortality, respectively, of D. gallinae adults at 48 h. Among (Z)-ligustilide, acaricides (bifenthrin, cypermethrin and spinosad) and butylidenephthalide, bifenthrin displayed the highest acaricidal activity, and the activity of butylidenephthalide was 2.3-fold higher than that of (Z)-ligustilide. These results suggest that C. officinale-derived material can be used for the development of a control agent for D. gallinae.