Acaricide Treatments Research Articles

Interaction between anti-tick vaccine and a macrocyclic lactone improves acaricidal efficacy against Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae) in experimentally infested cattle

The southern cattle fever tick (SCFT) Rhipicephalus (Boophilus) microplus, is considered the most important ectoparasite of livestock in the world because of high financial losses associated with direct feeding and transmission of the hemoparasites Babesia bovis, B. bigemina, and Anaplasma marginale. Unfortunately, SCFT in many parts of the world have evolved resistance to all market-available pesticides thus driving development of new control technologies. Vaccination against ticks using the tick gut protein Bm86 has been shown to be effective against acaricide-resistant ticks. This technique has been successfully implemented in Puerto Rico for the control of acaricide-resistant R. microplus on dairy and beef cattle. Observations from Puerto Rico indicate a potentially positive interaction between anti-tick vaccination when used in conjunction with systemic acaricide treatment. In this project, controlled animal studies were completed directly comparing efficacy of anti-tick vaccination with and without systemic acaricide. Results show that the Bm86 anti-tick vaccine in combination with the macrocyclic lactone, Moxidectin, expressed a synergistic interaction, providing greater and longer efficacy than either treatment alone.

Varroa destructor resistance to tau-fluvalinate: relationship between in vitro phenotypic test and VGSC L925V mutation.

Varroa destructor is a parasitic mite of the honey bee, Apis mellifera. Its presence in colonies can lead to a collapse within a few years. The use of acaricides has become essential to manage the hive infestation. However, the repeated and possibly incorrect use of acaricide treatments, as tau-fluvalinate, has led to the development of resistance. The in vitro phenotypic test allows the proportion of susceptible or resistant individuals to be known following an exposure to an active substance. In Varroa mites, resistance to tau-fluvalinate is associated with the presence of mutations at the position 925 of the voltage-gated sodium channel (VGSC). Here, we compared the results obtained with an in vitro phenotypic test against tau-fluvalinate and those obtained with an allelic discrimination assay on 13 treated and untreated Varroa populations in France. The correlation between the phenotype and the genetic profile rate is found to be 0.89 Varroa mites having resistant phenotypic profile have a probability of 63% to present the L925V mutation (resistance detection reliability). However, 97% of the Varroa mites having the susceptible phenotype do not present the L925V mutation (susceptible detection reliability). The L925V mutation explains most of the resistance to tau-fluvalinate in V. destructor in the populations tested. However, other mutations or types of resistance may also be involved to explain the survival of Varroa mites in the phenotypic test. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Epizootic and epidemiological risks associated with development of Platov airport infrastructure (Rostov-on-Don)

Objective. To identify the potential epizootic and epidemiological risks arising from the development of the infrastructure of Platov Airport in the territory adjacent to the airport for the development, if necessary, of a set of anti-epidemic and preventive measures.
 Materials and methods. Epizootological monitoring was carried out in the vicinity of Platov airport, as well as on the territory of the complex itself for three seasons (20192021). The capture of small mammals was carried out according to the standard method of trap-lines with Hero crushers; 1200 trap-days were accumulated. Route records of bats with the determination of their species were carried out. The species belonging of blood-sucking arthropods was determined using determinants. Regulatory support for the above monitoring was formed in accordance with the current normative and methodological documents: SanPiN 3.3686-21 "Sanitary and Epidemiological Requirements for the Prevention of Infectious Diseases"; MP 3.1.0211-20 "Trapping, Accounting and Forecasting the Number of Small Mammals and Birds in Natural Foci of Infectious Diseases"; MU 3.1.3012-12 "Collection, Accounting and Preparation for Laboratory Examination of Blood-sucking Arthropods in Natural Foci of Dangerous Infectious Diseases".
 Laboratory studies of samples of extracted biomaterial for the search of markers of pathogens of natural focal infections were carried out taking into account the requirements of current regulatory documents. Samples for laboratory testing were formed in compliance with the principle of "one point of collection of material, one time of collection of material, one type of material".
 Results. The results of epizootological monitoring of the territory of the Platov airport (Rostov-on-Don) are presented, according to which a real possibility of the development of epizootics of dangerous infectious diseases among small mammals living in the adjacent territory to the Platov airport has been established. In order to eliminate potential risks that can lead to complications of the epidemiological situation, it is necessary to carry out planned deratization and acaricide treatments on the territory of Platov airport. The continuation of regular epizootological monitoring of the airport territories and adjacent territories remains very relevant.
 Conclusions. The results of epizootological monitoring of the territory of the Platov International Airport (Rostov-on-Don) revealed the presence of mouse-like rodents penetrating from the surrounding fields, including those belonging to groups I and II of infectious sensitivity to tularemia, which form potential epizootological risks. A comprehensive laboratory study of biological material obtained from mouse-like rodents captured during epizootological monitoring did not reveal markers of pathogens of natural focal infections. At the same time, systematic regular epizootological monitoring of the airport territory is necessary due to the presence in the territories surrounding the airport complex of natural foci of particularly dangerous infections common to humans and animals, where mouse-like rodents live and reproduce, including house mice and rats, capable of migrating and inhabiting residential and warehouse premises and in case of activation of epizootic process to introduce infection into the territory of the airport complex, especially in autumn and winter.

Genetic diversification of an invasive honey bee ectoparasite across sympatric and allopatric host populations.

Invasive parasites are major threats to biodiversity. The honey bee ectoparasite, Varroa destructor, has shifted host and spread almost globally several decades ago. This pest is generally considered to be the main global threat to Western honey bees, Apis mellifera, although the damages it causes are not equivalent in all its new host's populations. Due to the high virulence of this parasite and the viruses it vectors, beekeepers generally rely on acaricide treatments to keep their colonies alive. However, some populations of A. mellifera can survive without anthropogenic mite control, through the expression of diverse resistance and tolerance traits. Such surviving colonies are currently found throughout the globe, with the biggest populations being found in Sub-Saharan Africa and Latin America. Recently, genetic differences between mite populations infesting surviving and treated A. mellifera colonies in Europe were found, suggesting that adaptations of honey bees drive mite evolution. Yet, the prevalence of such co-evolutionary adaptations in other invasive populations of V. destructor remain unknown. Using the previous data from Europe and novel genetic data from V. destructor populations in South America and Africa, we here investigated whether mites display signs of adaptations to different host populations of diverse origins and undergoing differing management. Our results show that, contrary to the differences previously documented in Europe, mites infesting treated and untreated honey bee populations in Africa and South America are genetically similar. However, strong levels of genetic differentiation were found when comparing mites across continents, suggesting ongoing allopatric speciation despite a recent spread from genetically homogenous lineages. This study provides novel insights into the co-evolution of V. destructor and A. mellifera, and confirms that these species are ideal to investigate coevolution in newly established host-parasite systems.

Acaricides Resistance in Ticks: Selection, Diagnosis, Mechanisms, and Mitigation.

Ticks are blood-feeding ecto-parasites that have a cosmopolitan distribution in tropical and subtropical regions of the world. Ticks cause economic losses in the form of reduced blood, meat and dairy products, as well as pathogen transmission. Different acaricides such as organochlorines, organophosphates, formamidines (e.g. amitraz), synthetic pyrethroids, macrocyclic lactones, fipronil, and fluazuron are currently used sequentially or simultaneously to control tick infestations. Most acaricide treatments now face increasingly high chances of failure, due to the resistance selection in different tick populations against these drugs. Acaricide resistance in ticks can be developed in different ways, including amino acid substitutions that result in morphological changes in the acaricide target, metabolic detoxification, and reduced acaricide entry through the outer layer of the tick body. The current literature brings a plethora of information regarding the use of different acaricides for tick control, resistance selection, analysis of mutations in target sites, and resistance mitigation. Alternatives such as synergistic use of different acaricides, plant-derived phytochemicals, fungi as biological control agents, and anti-tick vaccines have been recommended to avoid and mitigate acaricide resistance. The purpose of this review was to summarize and discuss different acaricides applied for tick control, their mechanisms of action and resistance selection, genetic polymorphisms in their target molecules, as well as the approaches used for diagnosis and mitigation of acaricide resistance, specifically in Rhipicephalus microplus ticks.

Discomfort Behaviour and Hair Coat Density of Muurah × Nili-Ravi Cross-bred Buffaloes as Affected by Louse (Haematopinus tuberculatus) Treated with Acaricides

Buffalo farming is an important component of Sri Lankan dairy industry. Ecto-parasites live on the surface of epidermis cause irritation and associated discomfort behaviours leading to energy loss and finally affect to reduce the performance of buffaloes. Objective of the study was to investigate the significance of Louse (Haematopinus tuberculatus) infestation on discomfort behavior and hair coat density of Muurah × Nili-Ravi cross-bred buffaloes reared under semi-intensive farming in Kamburupitiya area in Southern Province in Sri Lanka. Lactating female buffaloes (n=5) represented from parity 1 to 5 were purposively selected to the study. Lice count (LC) and lice egg count (LEC) per unit body area and the hair coat density (HCD) were measured periodically at 5,10,15,20 and 25 days after application of acaricides. Six random samples were taken. Direct focal observations were made to understand the discomfort behaviors (scratching, rubbing, licking, tail wagging and ear wagging) using an ethogram. Variation of LC after treatment was tested using repeated measure ANOVA. Main effects and interaction effects were tested. Correlations between LC and LEC with the HCD were tested. A strong positive correlation (r=0.909) was observed between LEC and the HCD whereas a weak positive correlation (r=0.439) was observed between LC and the HCD. With the prolongation of treatment time, the LC was increased and from day 15 to 25 it was significantly (p<0.05) increased. With the age advancement, the HCD was decreased. All the discomfort behaviors were significantly (p<0.05) increased with the prolongation of days after acaricide treatments. It is concluded that irrespective of the age, with the increased duration after applying acaricide treatment, lice infestation also simultaneously increased causing discomfort to the animals. Application of acaricides again at 15 days is recommended to control lice and to free the buffaloes from discomfort.
 Keywords: Acaricides, Buffalo, Discomfort behaviors, Hair coat density, Lice infestation

JMM Profile: Louping ill virus.

Louping ill virus (LIV) is a single-stranded, positive-sense RNA virus within the genus Flavivirus that is transmitted to vertebrate hosts by bites from infected ticks, the arthropod vector. The virus affects livestock in upland areas of Great Britain and Ireland, resulting in a febrile illness that can progress to fatal encephalitis. Prevention of the disease is facilitated by combining acaricide treatment, land management and vaccination strategies. However, vaccines have been discontinued in recent years. Although rare, LIV can be transmitted to and cause disease in humans. Consequently, LIV infection is a threat to human and veterinary health and can impact on the rural economy.

The use of unmanned aerial vehicles for acaricide treatments

The use of unmanned aerial vehicles for acaricide treatments

Selection of stable reference genes for quantitative real-time PCR in the Varroa mite, Varroa destructor.

To investigate the acaricide toxicity and resistance mechanisms in the Varroa mite, it is essential to understand the genetic responses of Varroa mites to acaricides, which are usually evaluated by transcriptional profiling based on quantitative real-time polymerase chain reaction(qPCR). In this study, to select reference genes showing consistent expression patterns regardless of the acaricide treatment or the type of tissue, Varroa mites treated with each of the three representative acaricides (coumaphos, fluvalinate, and amitraz) were processed for transcriptomic analysis, from which eight genes (NADH dehydrogenase[NADHD], glyceraldehyde-3-phosphate dehydrogenase[GAPDH], eukaryotic translation elongation factor 1 α 1[eEF1A1], eukaryotic translation elongation factor 2[eEF2], ribosomal protein L5[RpL5], Actin, tubulin α-1D chain[α-tubulin], and Rab1) were selected as candidates. The transcription profiles of these genes, depending on the treatment of the three acaricides or across different tissues (cuticle, legs, gut/fat bodies, and synganglion), were analyzed using qPCR with four validation programs, BestKeeper, geNorm, NormFinder, and RefFinder. Following acaricide treatment, eEF1A1 and NADHD showed the least variation in their expression levels, whereas the expression levels of α-tubulin and RpL5 were the most stable across different tissue groups. Rab1/GAPDH and Actin/eEF2 showed the least stable expression patterns following acaricide treatments and across different tissues, respectively, requiring precautions for use. When vitellogenin gene expression was analyzed by different reference genes, its expression profiles varied significantly depending on the reference genes, highlighting the importance of proper reference gene use. Thus, it is recommended using eEF1A1 and NADHD as reference genes for the comparison of the effects of acaricide on the whole body, whereas α-tubulin and RpL5 are recommended for investigating the tissue-specific expression profiles of target genes.

Field efficacy assessment of a vaccine against Rhipicephalus (Boophilus) australis in New-Caledonia.

Pure European bovine breeding is compromised in South Pacific (i.e. Australia, New Caledonia) due to the impact of acaricide-resistant Rhipicephalus (Boophilus) australis ticks. Farmers need new solutions to sustainably maintain their activity. An integrated tick control program has been applied for 2years in herds of European breeds (i.e. Charolais and Limousine cattle breeds) in New Caledonia. A field trial including the use of a vaccine based on a local Bm86 antigen, agropastoral measures and a chemical control of the tick was conducted to assess the possibility to reduce the number of acaricidal treatments. Nine farms including 1400 animals were monitored from July 2017 to June 2020. The year mid2017-mid2018 was the year of initial monitoring in order to get control data related to tick infestation during the seasons and to the number of treatments per herd. Vaccinations began between September and December 2018. Results obtained from mid2019 to mid2020 were then compared to the initial period (mid2017-mid2018) to assess the benefits of the vaccine. The average annual number of acaricide treatments decreased significantly from 7.44 before vaccination to 4.45 during mid2019-mid2020 (p=0.026). Infestation scores, assessed by tick counts when farmers grouped the cattle to apply acaricides, showed a constant and low infestation level. Nevertheless, farmers were willing to tolerate slightly higher tick loads on vaccinated cattle with less acaricidal treatments compared to unvaccinated and frequently treated cattle. Local cutaneous reactions were recorded at the injection site with 46.6% of all injections evolving into nodules and 1% of injections giving depilation or abscesses. At the end of the trial, all the breeders wish to continue the vaccination and consider that it is now possible to serenely maintain their breed.

Demodex: The worst enemies are the ones that used to be friends.

Demodex mites are common ectoparasites of the human pilosebaceous units. Most adults are infested with Demodex mites without clinical symptoms. Demodex mite will only become a pathogenic organism when there is an abnormal increase in the number of Demodex mite density. This situation happens when the equilibrium between Demodex mites, skin microenvironment and human immunity system changes. Demodex infestation can cause multiple skin disorders, which are grouped under the term demodicosis or demodicidosis. Clinical manifestations of demodicosis can mimic other known skin diseases such as folliculitis, rosacea, perioral dermatitis, which is why it is often misdiagnosed. Diagnosis criteria consists of relevant correlation of suspected clinical skin lesions, confirmed by the presence of abnormal proliferation of Demodex mites and by clinical cure after acaricidal treatment together with normalization of Demodex mite density. Dermatologists should be aware that demodicosis is not an uncommon skin disease, and there are still many unknowns about it that should be researched further.

Assessment of synthetic acaricide residues in Royal Jelly

In this study, Royal Jelly was produced from colonies under chemical treatment of coumaphos (Perizin and Checkmite+) and tau-fluvalinate (Apistan), using artificial plastic queen cells. The contamination level was assessed 42 days after the application. The application of CheckMite + strips during the production led to higher levels of acaricide residues in the final product, in contrast to the residues from Perizin and Apistan. For this reason, the CheckMite + strips were further applied in order to assess the contamination of the product after a long period (292 days after the application). For the specific sampling, natural (center and adjacent) and plastic cells were used. The results showed that the contamination of Royal Jelly produced in plastic queen cells decreased with time; one month after removing the strips, residues were not detectable. On the contrary, the contamination of samples collected from natural queen cells was high, particularly from those adjacent to the strips, where even 292 days after the strips’ removal, coumaphos concentration was 2.25 ± 0.50 mg kg−1. The maximum concentration (12.52 ± 2.24 mg kg−1) was detected in natural queen cells. Τo our knowledge, this is the highest contamination that has ever been recorded in a food product. Our results suggest that coumaphos may be transferred from wax to Royal Jelly even in low concentrations. Also, the findings of this research provide data for setting safe intervals between acaricide treatment and Royal Jelly production, raising at the same time awareness about the impact of wax contamination on honey bees’ health.

Evaluation of field efficacy of some selected acaricides against Tetranychus urticae Koch on okra

An experiment was conducted to evaluate the field level efficacy of some selected acaricides against two spotted spider mites, Tetranychus urticae Koch at Regional Research Station (Hill Zone), Uttar Banga Krishi Viswavidyalaya, Kalimpong, West Bengal, India during 2020 and 2021. Among the various acaricidal treatments, spiromesifen 22.9 SC@120 g a.i/ha was found to be the best treatment in terms of mean per cent reduction of mite population as well as providing the highest yield during both the years of study. This treatment was followed by hexythiazox 5.45EC @25 g a.i./ha and fenazaquin 10 EC @ 125 g a.i./ha. Propagite 57 EC @ 850 g a.i./ha was found to be the least effective treatment although it was significantly superior to the control.

Epidemiological Community and Differences of Transmissive Infections in Astrakhan Region

Relevance. The territory of the Astrakhan region hosts natural foci of severe infections of arbovirus etiology – Crimean-Congo hemorrhagic fever (CCHF) and Astrakhan fever (spotted fever resembling the Mediterranean spotted fever, Astrakhan spotted fever (ASF). The long-term average incidence of CCHF and ASF in the Astrakhan region is to 11 and 135 times higher, respectively, than the average incidence in the Russian Federation. Aims. To present, based on epidemiological data, a comparative characterization of transmissible infections of CCHF and ASF in the Astrakhan region. Materials & Methods. The main method of the study was epidemiological. The data for 2000−2016 of primary medical documentation Ф.058/у «Emergency notification of infectious disease, food, acute occupational poisoning, unusual reaction to vaccination», federal statistical observation Ф. 2 «Information on infectious and parasitic diseases», Ф. 357/у «Epidemiological examination card of infectious disease focus», Ф. .003/у «Medical card of inpatient patient», presented by Center of hygiene and epidemiology in Astrakhan region. For retrospective epidemiological analysis, we studied the absolute and intensive morbidity indicators (per 100 ths population), by age, professional groups, and among the urban and rural population. Based on the average long-term morbidity indicators of the population, a mapping of the territory of the Astrakhan region was carried out. The influence of natural and climatic conditions on the epidemic process of CCHF and ASF was assessed by meteorological data (amount of precipitation, air temperature, etc.). Materials of long-term observation over 11 districts of Astrakhan region and Astrakhan city were analyzed, including data on the spread of Ixodid ticks, population contact with them (according to the attendance of people to treatment-and-prophylactic organizations of the region). Statistical data processing was carried out using the method of straight-line alignment of dynamic series of morbidity indicators, calculation of the average annual rate of decrease/increase. Correlation analysis was used to assess the direction and strength of the relationship between the indicators, and quantitative dependence between epidemic process characteristics. Differences between the indicators were considered to be reliable if p < 0.05. Results. During the analyzed period 151 cases of CCHF and 3951 cases of ASF were identified. By 2016. CCHF was registered in all 11 districts of the region and the area of foci covered 44,000 km2 and 44,100 km2, respectively. There are no differences significantly affecting the epidemic process of CCHF and ASF, so preventive measures are mainly aimed at controlling the vectors of the pathogens of these infections. The comprehensive study of the territory of Astrakhan region carried out in 2000–2016 revealed expansion of CCHF and ASF areal of disease (by 11.8% and 23.4% respectively) and determined the territories with the highest risk of infection, which allowed to increase and redistribute the volumes of acaricide treatments of the territories with the highest infection risk and ensure the decrease of CCHF and ASF morbidity rates. Conclusion. As a result of the comprehensive study conducted in 2000–2016 in the territory of Astrakhan region, the expansion of CCHF and ASF areal of disease was revealed (by 11.8% and 23.4% respectively) and the areas of highest infection risk were identified, which allowed to increase and redistribute the volume of acaricide treatments of the areas of highest infection risk and ensure the reduction of CCHF and ASF morbidity.

Haplotype Analysis of Varroa destructor and Deformed Wing Virus Using Long Reads.

As a phoretic parasite and virus vector, the mite Varroa destructor and the associated Deformed wing virus (DWV) form a lethal combination to the honey bee, Apis mellifera. Routine acaricide treatment has been reported to reduce the diversity of mites and select for tolerance against these treatments. Further, different DWV strains face selective pressures when transmitted via mites. In this study, the haplotypes of Varroa mites and associated DWV variants were quantified using long reads. A single haplotype dominated the mite mitochondrial gene cytochrome oxidase subunit I, reflecting an ancient bottleneck. However, highly polymorphic genes were present across the mite genome, suggesting the diversity of mites could be actively maintained at a regional level. DWV detected in both mites and honey bees show a dominant variant with only a few low-frequency alternate haplotypes. The relative abundances of DWV haplotypes isolated from honey bees and mites were highly consistent, suggesting that some variants are favored by ongoing selection.

Evaluating the Efficacy of 30 Different Essential Oils against Varroa destructor and Honey Bee Workers (Apis mellifera).

Simple SummaryWorldwide, mass losses of honey bee colonies are being observed more frequently due to Varroa mite infestation. Therefore, varroosis is considered a major problem in beekeeping participating to a large extent in colony collapse disorder. Except for direct damage of bees and suppressing their immune system caused by parasitism, Varroa mites transfer viral particles straight to bee hemolymph which can have a fatal impact. To control the mite population, several acaricidal treatments are used. Commonly used treatments are synthetic acaricides with a high risk of developing Varroa resistance population and contamination of bee products by acaricidal residues. Other commonly used treatments are organic acids, which are increasingly associated with damage of brood, adult bees, and premature deaths of queens. Therefore, in this study, we evaluated the varroacidal effect of 30 individual essential oils. The toxicity of the most effective oils selected by screening was subsequently tested on Varroa mites and adult honey bee workers simultaneously. In addition, the main components of these essential oils were specified. Several essential oils were proven to be effective against the adult female of Varroa mites and at the same dose safe for adult honey bee workers under laboratory conditions, especially manuka, peppermint, oregano, litsea, and cinnamon.Essential oils and their components are generally known for their acaricidal effects and are used as an alternative to control the population of the Varroa destructor instead of synthetic acaricides. However, for many essential oils, the exact acaricidal effect against Varroa mites, as well as the effect against honey bees, is not known. In this study, 30 different essential oils were screened by using a glass-vial residual bioassay. Essential oils showing varroacidal efficacy > 70% were tested by the complete exposure assay. A total of five bees and five mites were placed in the Petri dishes in five replications for each concentration of essential oil. Mite and bee mortality rates were assessed after 4, 24, 48, and 72 h. The LC50 values and selectivity ratio (SR) were calculated. For essential oils with the best selectivity ratio, their main components were detected and quantified by GC-MS/MS. The results suggest that the most suitable oils are peppermint and manuka (SR > 9), followed by oregano, litsea (SR > 5), carrot, and cinnamon (SR > 4). Additionally, these oils showed a trend of the increased value of selective ratio over time. All these oils seem to be better than thymol (SR < 3.2), which is commonly used in beekeeping practice. However, the possible use of these essential oils has yet to be verified in beekeeping practice.

Mites from the family Phytoseiidae as an element of an anti-resistant strategy for protecting fruit plantations from spider mites

In the last decade, the acarocomplex of apple orchards in the plain-steppe zone of the Crimea was dominated by two species of mites, fam. Tetranychidae - Amphitetranychus viennensis (Zacher) and Panonychus ulmi (Koch). Their share in the complex of phytophagous mites was 52.5 and 32.0%, respectively. Against the background of repeated acaricidal treatments during the season, the emergence of resistant races of phytophagous mites was recorded. The proposed anti-resistant strategy for controlling the number of spider mites on an apple tree involves the use of Phytoseiulus persimilis (Athias-Henriot), Neoseiulus californicus (McGregor), and Amblyseius andersoni (Chant). The combination of methods of seasonal colonization by phytoseiids serves as the building blocks of an anti-resistant defense system.Resettlement in the spring, by flooding, of two species of acariphages, P. persimilis and A. andersoni , contributes to the formation of acarofauna, so that while the first species reduces the number of phytophagous mites (by 50-60%), the second adapts and starts feeding later, and, at the expense of daughter individuals, it allows to reduce the number of pests by the end of the second decade of June to 2-3 individuals / leaf. In summer, a double release of the predatory mite N. californicus with a norm of 30 thousand individuals / ha (150-300 individuals / every 10 trees) reduces the risk of mass reproduction of spider mites at high average daily temperatures and low humidity.

Residual Tau-Fluvalinate in Honey Bee Colonies Is Coupled with Evidence for Selection for Varroa destructor Resistance to Pyrethroids.

Simple SummaryVarroa destructor is one of the most prevalent honey bee (Apis mellifera) pathogens worldwide. Nowadays, the main method to control this parasite involves the application of different acaricidal treatments, among which the pyrethroid tau-fluvalinate is one of the most widely used. However, the intensive and repetitive application of these chemicals generates a selective pressure that, when maintained over time, contributes to the emergence of resistant mites in the honey bee colonies. Here we analysed the presence of residual tau-fluvalinate and the patterns of genetic resistance to this acaricide in Varroa mites collected from tau-fluvalinate untreated honey bee colonies. Our results show the widespread and persistent pyrethroid contamination of beeswax and beebread in the hives, along with an excess of pyrethroid-resistant genotypes and an overall increase in the frequency of the pyrethroid-resistant allele in the mite population over time. Persistent contamination of the hives likely compromises the efficacy of tau-fluvalinate treatments and, therefore, may have serious long-term consequences for the control of varroosis.Varroa destructor is considered one of the most devastating parasites of the honey bee, Apis mellifera, and a major problem for the beekeeping industry. Currently, the main method to control Varroa mites is the application of drugs that contain different acaricides as active ingredients. The pyrethroid tau-fluvalinate is one of the acaricides most widely used in beekeeping due to its efficacy and low toxicity to bees. However, the intensive and repetitive application of this compound produces a selective pressure that, when maintained over time, contributes to the emergence of resistant mites in the honey bee colonies, compromising the acaricidal treatments efficacy. Here we studied the presence of tau-fluvalinate residues in hives and the evolution of genetic resistance to this acaricide in Varroa mites from honey bee colonies that received no pyrethroid treatment in the previous four years. Our data revealed the widespread and persistent tau-fluvalinate contamination of beeswax and beebread in hives, an overall increase of the pyrethroid resistance allele frequency and a generalized excess of resistant mites relative to Hardy–Weinberg equilibrium expectations. These results suggest that tau-fluvalinate contamination in the hives may seriously compromise the efficacy of pyrethroid-based mite control methods.

Integrated control of the cattle tick, Rhipicephalus australis (Acari: Ixodidae), in New Caledonia through the Pasture and Cattle Management method.

Development of the Pasture and Cattle Management (PCM) method is a priority to control the cattle tick, Rhipicephalus australis, in New Caledonia. The PCM method provides the foundation for sustainable integrated tick control because approximately 95% of cattle ticks in infested pastures are off the host in the non-parasitic life stages, and the practice of treating cattle intensely with chemical acaricides is a risk for the emergence of resistance to these active ingredients in commercial acaricidal products available for veterinary use. Here, we report the findings of an assessment survey to document the utility of the PCM method. Analyses of questionnaire data provided by 21 beef cattle producers describing their management of 37 herds informed how to (1) assess the ability of PCM to reduce acaricide use and (2) prioritize best practices and define recommendations to breeders promoting efficient tick control with minimum acaricide use. Boosted regression tree analysis showed a significant (p = 0.002) reduction of ≈33% in the number of acaricide treatments from 7.9 to 5.3 per year by using PCM. Of the 24 factors identified as potentially affecting acaricide use, six factors accounted for ≈86% of the variability in number of acaricide treatments applied annually. The six most influential factors involved farm characteristics as well as pasture and herd management recommendations. These results demonstrated the usefulness of PCM for integrated control of R. australis infestations while reducing acaricide use to improve cattle production in New Caledonia.

Potential causes of Acaricide Resistance in Rhipicephalus and Amblyomma Ticks (Acari: Ixodidae) in Namwala District, Zambia

Acaricide resistance in ticks poses a great threat to livestock production in many parts of the world where ticks are a problem. The objectives of this study were to screen for acaricide resistance in Rhipicephalus and Amblyomma ticks using phenotypic and molecular assays, and to assess current tick control practices used by cattle farmers in the traditional sector of Namwala District. The larval packet test was used to screen for acaricide resistance in ticks covering concentrations up to twice the discriminatory dose for amitraz, diazinon and cypermethrin. Genetic mutations associated with resistance to amitraz (A22C-T8P and T65C-L22S), and organophosphates/ pyrethroids (G1120A) were screened using polymerase chain reaction and sequencing. Information on tick control practices at the household level was collected using a semi-structured questionnaire. Intermediate resistance (21-50%) to amitraz and cypermethrin was detected in both Rhipicephalus and Amblyomma ticks, with both tick genera showing susceptibility to diazinon (&lt;10%). None of the ticks in this study had the reported acaricide resistance-conferring molecular markers that were screened for. The findings suggest that the resistance detected in the studied tick population may be due to other mechanisms yet to be identified. Tick control practices observed amongst the farmers, such as incorrect use of acaricide concentrations and rotations, could be fuelling the development of acaricide resistance. Considering that acaricide treatment is the mainstay of tick control in the country, it is thus critical to comprehensively unravel the factors contributing to treatment failure as this would allow for the application of appropriate remedial actions for effective tick control in Zambia.