Acaricide Application Research Articles

Assessment of Seroprevalence and Associated Risk Factors for Anaplasmosis in Camelus dromedarius.

(1) Background: Anaplasmosis is an infectious disease in camels caused by an obligate intracellular bacterium that is transmitted by ticks. (2) Methods: A cross-sectional study was conducted during 2020 to study the seroprevalence of Anaplasma spp. among Camelus dromedarius in three governorates in Egypt and assess the associated risk factors. Serum samples from 365 camels were examined by a competitive enzyme-linked immunosorbent assay (cELISA) test. (3) Results: Overall, the seroprevalence of anaplasmosis among camels was 18.6%. Multivariable logistic regression was performed, and it was discovered that tick infestation, application of acaricides, grooming practice and body condition were potential risk factors for Anaplasma spp. infection (odds ratio > 1) in dromedary camels. In contrast, the locality in which the camels lived and their age were not significant effects with regard to the occurrence of anaplasmosis. (4) Conclusions: The current findings suggest that improvement of protective measures to limit the effects of the identified risk factors can help to reduce the spread of anaplasmosis among camels in Egypt.

EFECTO DE ACARICIDAS QUÍMICOS EN LA MORTALIDAD DE LA ARAÑA ROJA Tetranychus urticae KOCH (Acari: Tetranychidae)

<p><strong>Background.</strong> Chemical acaricides with different modes of action are an effective alternative for the management of <em>T. urticae</em> and to prevent the selection of resistant population. Objective. To evaluate the effect of chemical acaricides of different toxicological groups on the mortality of <em>T. urticae</em>. <strong>Methodology.</strong> To evaluate the acute toxicity, mites were exposed to leaf discs of eggplants that had been immersed in the acaricides. The mortality was recorded at 4 h period for a total of 48 h. To evaluate the residual effect, the acaricides were applied to eggplant plants, leaf discs were obtained at different periods (1 - 32 days after acaricide application) and <em>T. urticae</em> adults and nymphs were exposed to the leaf discs. <strong>Results</strong>. Abamectin, spirodiclofen and fenpyroximate had the fastest effects in adults and nymphs (4 h after application). Abamectin, spirodiclofen and fenpyroximate had long-term effects, for up to two weeks. Spirodiclofen, fenpyroximate and acequinocyl had also ovicidal effect. <strong>Implication.</strong> Chemical acaricides with different mode of action represent a viable option for the management of <em>T. urticae</em> and the prevention of the selection of resistant populations. <strong>Conclusión.</strong> Abamectin, spirodiclofen, and fenpyroximate are highly toxic against adults and immature <em>T. urticae</em>.</p>

Variability of infestation of rose varieties by the spider mite Tetranychus urticae under conditions of application of Phytoseiulus persimilis or acaricides

The two-spotted spider mite Tetranychus urticae is a dangerous polyphagous pest of agricultural and ornamental plants. In a commercial greenhouse treated with acaricides or biological control using predatory mite Phytoseiulus persimilis individual varieties of roses differed significantly in terms of the average annual infestation by the pest mite. On the poorly populated rose varieties, the biological control agent application was more effective as compared to the acaricides. To effectively control the pest, the required predatory mite rates were 4.6–8.7 times higher on varieties with a minimal spider mite infestation (Aqua and Deep Water) as compared to the maximal pest infestation (Heaven and Brazil).

Selectivity and molecular stress responses to classical and botanical acaricides in the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae).

Acaricide application remains an integral component of integrated pest management (IPM) for the two-spotted spider mite Tetranychus urticae. Species and strains of phytoseiid predatory mites vary significantly in their response to acaricides. For the success of IPM, it is imperative to identify the determinants of selectivity and molecular stress responses of acaricides in predatory mites. The three classical acaricides bifenazate, cyflumetofen, and fenbutatin oxide did not affect the survival and fecundity of Phytoseiulus persimilis regardless of the route of exposure. Selectivity of the orange oil and terpenoid blend-based botanical acaricides was low via a combination of direct exposure, acaricide-laced diet, and residual exposure but improved when limiting exposure only to diet. To gain insights into the molecular stress responses, the transcriptome of P. persimilis was assembled. Subsequent gene expression analysis of predatory mites orally exposed to fenbutatin oxide and orange oil yielded only a limited xenobiotic stress response. In contrast, P. persimilis exhibited target-site resistance mutations, including I260M in SdhB, I1017M in CHS1, and kdr and super-kdr in VGSC. Extending the screen using available Phytoseiidae sequences uncovered I136T, S141F in cytb, G119S in AChE, and A2083V in ACC, well-known target-sites of acaricides. Selectivity of the tested botanical acaricides to P. persimilis was low but could be enhanced by restricting exposure to a single route. Differential gene expression analysis did not show a robust induced stress response after sublethal exposure. In contrast, this study uncovered target-site mutations that may help to explain the physiological selectivity of several classical acaricides to phytoseiid predators.

Tick Immunobiology and Extracellular Traps: An Integrative Vision to Control of Vectors.

Ticks are hematophagous ectoparasites that infest a diverse number of vertebrate hosts. The tick immunobiology plays a significant role in establishing and transmitting many pathogens to their hosts. To control tick infestations, the acaricide application is a commonly used method with severe environmental consequences and the selection of tick-resistant populations. With these drawbacks, new tick control methods need to be developed, and the immune system of ticks contains a plethora of potential candidates for vaccine design. Additionally, tick immunity is based on an orchestrated action of humoral and cellular immune responses. Therefore, the actors of these responses are the object of our study in this review since they are new targets in anti-tick vaccine design. We present their role in the immune response that positions them as feasible targets that can be blocked, inhibited, interfered with, and overexpressed, and then elucidate a new method to control tick infestations through the development of vaccines. We also propose Extracellular Traps Formation (ETosis) in ticks as a process to eliminate their natural enemies and those pathogens they transmit (vectorial capacity), which results attractive since they are a source of acting molecules with potential use as vaccines.

Study on Prevalence of Hard Ticks and Their Associated Risk Factors in Small Ruminants of Boloso Sore Districts of Wolaita Zone, Southern Ethiopia.

BackgroundTicks and tick-borne infections are the most serious health threats to small ruminants in Ethiopia, resulting in huge economic losses.MethodsA cross-sectional study using a simple random sampling technique was conducted to determine the prevalence and potential risk factors of hard ticks in small ruminants of the Boloso Sore district of Wolaita Zone. Ticks were identified to species level under a stereomicroscope using morphological identification keys.ResultsFrom a total of 400 examined animals, 68.75% (275/400) of them were infested with hard ticks with the respective prevalence of 69.09% (152/220) in goats and 68.33% (123/180) in sheep. A total of 1192 (552 males and 640 females) adult ixodid ticks that belong to a total of four species, which were grouped under three genera: Amblyomma, Hyalomma, and Rhipicephalus, and one subgenus; Boophilus were collected from the head, ear, under tail and legs of goats and sheep. In this study, Amblyomma variegatum 44.97% (536/1192) was found to be the most abundant tick species followed by Boophilus decoloratus 30.79% (367/1192), Rhipicephalus pulchellus 20.47% (244/1192), and Hyalomma truncatum 3.77% (45/1192). The sex, age, and body condition score of animals with a high prevalence of hard ticks showed statistically significant differences (p<0.05). Male ticks dominated females in all cases except for Boophilus decoloratus. There was no statistically significant relationship (p > 0.05) between tick infestation and animal origin or species.ConclusionTicks were the most significant production and health constraints for small ruminants in the study region. Therefore, the increasing threat of ticks of small ruminants warrants urgent strategic application of acaricides and the creation of awareness among livestock owners to prevent and control tick infestation.

Acaricidal activity of Shirazian thyme and rosemary methanolic extracts in combination with spirodiclofen and propargite on Tetranychus urticae (Acari: Tetranychidae)

The two-spotted spider mite, Tetranychus urticae Koch is one of the polyphagous pests that attack a wide range of crops. In recent decades, excessive application of synthetic acaricides has led to its resistance to pesticides and environmental pollution. However, considering the importance of the role of pesticides in controlling plant pests, it is impossible to cease using these compounds. In recent decades, new methods such as the use of plant extracts have been proposed that not only control pests but also have no residues and harmful environmental effects. Also, the use of plant extracts in combination with synthetic pesticides while controlling the pest, reduces the amount of pesticide usage. In this study, the efficacy of methanolic extracts of Zataria multiflora and Rosmarinus officinalis was investigated individually and in combination with spirodiclofen and propargite to control two-spotted spider mites. Bioassay tests were performed using the leaf dipping method. Each treatment was performed in three independent biological replications and the mortality was recorded 24 h after exposure. The 50% lethal dose (LC50) of spirodiclofen and propargite as well as methanolic extracts of Z. multiflora and R. officinalis were estimated to 1.89, 12.76, 1934.13, and 4382.07 mg/l, respectively. In addition, results of experiments related to mixing plant extracts with acaricides showed that the combination of Z. multiflora extract with spirodiclofen and propargite caused a synergistic effect with a co-toxicity coefficient of 66.66 and 55.55, respectively. However, the combination of R. officinalis extract with spirodiclofen and propargite caused an antagonistic response with −77.78 and −80.56, respectively.

Alternative applications of the strategic control against the cattle tick Rhipicephalus (Boophilus) microplus in a subtropical area.

Although different evaluations on the efficacy of the strategic control against Rhipicephalus microplus have been performed, the effects of successive applications of these schemes on the abundance of cattle ticks have not been evaluated. The aim of this work was to analyse the long-term effect of strategic applications of chemical acaricides on the R. microplus infestation in cattle in a subtropical area. These schemes are based on the application of three annual treatments between late winter and late spring. Additionally, a trial to evaluate the efficacy of the strategic control by deferring the first treatment from late winter to spring and the third treatment from late spring to summer was also carried out. The efficacy of the strategic control applied on 3 consecutive years was significant. The tick infestation in the treated group always remained at low levels, because mean number of ticks was almost never higher than 20. Regarding the trial where the third application of acaricide was deferred from spring to summer, and the first one from late winter to spring, the differences between treated and control group were significant in all post-treatment counts. The results of this study add evidence that support the sustainability of the strategic control in subtropical areas where the population dynamics of R. microplus is characterized by a well-marked seasonal pattern. Three relevant aspects were determined: (i) the feasibility and efficacy of successive applications of the strategic control in consecutive years; (ii) the time window to start the sequence of treatments is from late winter to mid-spring; (iii) it is achievable deferring the last treatment from late spring to summer if the tick infestation levels on cattle are low enough to allow it.

Identification and Prevalence of Ixodid Ticks of Cattle in case of Haramaya Eastern Hararghe, Ethiopia.

A cross-sectional study was conducted from December 2017 to April 2018 to determine the prevalence and identify major species of ixodid ticks of cattle and tick burden of different sex, age, breed, and body condition of cattle. Standard physical and direct stereomicroscopy techniques were employed for identification of tick species. During the study period, a total of 353 cattle were examined for presence of ticks and around 447 ticks were collected. The study showed that 34.3% cattle were infested with one or more tick species. The study reported different species of ticks in the order of their prevalence: A. variegatum (46.3%), Rh. decoloratus (20.1%), A. cohaerens (15.7%), A. gemma (11.9%), and Rh. pulchellus (6.04%), respectively. The prevalence of tick infestation between different risk factors such as sex, age, and body condition of cattle was statistically significant (p < 0.05). The overall male-to-female ratio of ticks was 2.29 : 1. Also, it was reported that, in A. variegatum, A. cohaerens, and A. gemma, the number of male exceeded that of female, but female number exceeded male number in case of Rh. decoloratus. The result also reported difference in attachment site preference, for example, Amblyomma genus was attached mostly to the scrotum/udder and axial and Rh. pulchellus was specified on the ear and perianal area, while Rh. decoloratus was non site selective. In conclusion, findings of this study suggest that ticks were the most important problems of cattle of the study areas. Therefore, the increasing threat of ticks warrants urgent strategic control including application of acaricides and creation of awareness among livestock owners about the veterinary importance of ticks for the integrated tick control.

Study on Prevalence of Ixodid Ticks of Goats and Acaricide Utilization Practices of Herd Owners in Benatsemay District, South Omo Zone, South-Western Ethiopia.

IntroductionTicks are major health problems of goats that contribute to a significant economic loss in Ethiopia.MethodsA cross-sectional study using a systematic random sampling technique was conducted to determine the prevalence, potential risk factors of hard ticks (Acarina: Ixodidae) of goats, and the acaricide utilization practice of herd owners in the Benatsemay district.ResultsOut of 285 examined goats, 85.26% of goats were found infested by Rhipicephalus and Amblyomma tick genera. The body condition score of goats was the only factor that was significantly (p < 0.05) associated with tick infestations. The frequently identified tick species were Rhipicephalus pulchellus (14.38%), Rh. decoloratus (11.22%), A. cohaerens (5.26%) and A. variegatum (4.21%), and mixed infestation (38.59%). Herd owner’s questionnaire survey revealed that 100% of interviewees responded that tick infestations were frequently encountered throughout the year and prevailed on aged goats (90%) and dry season (60%). Concurrent usage of ethnomedicinal plants and conventional acaricides were dominant practices to control tick infestation as responded by 60% of interviewees. Among the conventional acaricides, Diazinon and Ivermectin were the most practiced acaricides as replied by 90% of the respondents. Moreover, community animal health workers (CAHWs) (43.33%) and owners themselves (33.33%) were primarily responsible for acaricide application to tick-infested animals. About 66.67% of the livestock owner’s responses also disclosed that diazinon was the most effective acaricide followed by ivermectin (16.67%) and amitraz (6.67%). Finally, 56.57% of the respondents replied that acaricidal drugs from private veterinary drug shops were overpriced than the same acaricides from government veterinary clinics.ConclusionIn this study, there was a high prevalence of hard ticks in goats, and irrational application of acaricides was noted in the Benatsemay district; thus, appropriate tick control measures should be taken to minimize tick burden through using acaricides.

English

In Uganda, control of ticks and tick-borne diseases (TTBDs) largely depends on the use of chemicals applied using different methods. This cross-sectional study assessed 17 factors to determine the effectiveness and limitations in the use of the recently adopted acaricide application methods on dairy cattle farms in south-western Uganda. The average annual morbidity and mortality due to tick-borne diseases were 42.6 and 30.0% for farms using bucket pumps, 9.3 and 4.2% for those using motorised pumps and 3.0 and 1.0% for spray races, respectively. For a 20-year period, the estimated cost of acaricide application for a herd of 80 head of cattle was US$ 71,042, US$ 38,694 and US$ 28,710 when using a bucket pump, spray race and a motorised pump, respectively. Bucket pump method may only be cost-effective on farms of 40 to 112 head of cattle, while a motorised pump was only economical for farms of 35 to 170 cattle and a spray race being a better option at farms of 100 to 600 cattle. Farmers should make the most appropriate choice of acaricide application method to achieve the most effective control of TTBDs on their farms. Key words: Effectiveness, acaricide application methods, tick-borne diseases, Uganda.

Biological responses of Tetranychus urticae (Acari: Tetranychidae) to sub-lethal concentrations of the entomopathogenic fungus Beauveria bassiana.

Tetranychus urticae (Acari: Tetranychidae) is one of the most important pests of agricultural crops with worldwide distribution causing considerable damage to different products. Application of chemical acaricides is one of the most important strategies used for the control of this pest. Entomopathogenic fungi, however, have been proposed as alternative control agents. In this study, sub-lethal effects (LC10 = 6.76 × 102, LC20 = 8.74 × 103, and LC30 = 55.38 × 103 conidia ml-1) of Beauveria bassiana strain TV on the life table parameters of T. urticae were evaluated under laboratory conditions. The results demonstrated that by increasing the concentration, a significant decline was observed in adult longevity of both male and female individuals. Total fecundity of T. urticae was calculated as 45.16, 36.28, 23.98, and 18.21 eggs in control, LC10, LC20, and LC30 treatments, respectively. Sub-lethal concentrations drastically affected the population parameters of this mite pest. The intrinsic rate of increase (r) ranged from 0.1983 to 0.1688 day-1 for the mites treated with distilled water and LC20 treatments, respectively. The net reproductive rate (R0) was affected by the sub-lethal concentrations (lower value at LC30 concentration: 11.19 offspring/individual). Considering the detrimental effects of B. bassiana on some biological parameters of T. urticae, it can be concluded that this product can be used to develop targeted interventions aimed at integrated pest management of this pest.

Parallel evolution of Varroa resistance in honey bees: a common mechanism across continents?

The near-globally distributed ecto-parasitic mite of the Apis mellifera honeybee, Varroa destructor, has formed a lethal association with Deformed wing virus, a once rare and benign RNA virus. In concert, the two have killed millions of wild and managed colonies, particularly across the Northern Hemisphere, forcing the need for regular acaricide application to ensure colony survival. However, despite the short association (in evolutionary terms), a small but increasing number of A. mellifera populations across the globe have been surviving many years without any mite control methods. This long-term survival, or Varroa resistance, is consistently associated with the same suite of traits (recapping, brood removal and reduced mite reproduction) irrespective of location. Here we conduct an analysis of data extracted from 60 papers to illustrate how these traits connect together to explain decades of mite resistance data. We have potentially a unified understanding of natural Varroa resistance that will help the global industry achieve widespread miticide-free beekeeping and indicate how different honeybee populations across four continents have resolved a recent threat using the same suite of behaviours.

Bioactivity of oxymatrine and azadirachtin against Tetranychus evansi (Acari: Tetranychidae) and their compatibility with the predator Phytoseiulus longipes (Acari: Phytoseiidae) on tomato

Tetranychus evansi Baker &amp; Pritchard (Acari: Tetranychidae) is one of the main tomato pests in several countries, mainly in Africa, and applications of synthetic acaricides are the main strategy for its control. Efficient biopesticides to suppress pest populations, with low toxicity against natural enemies, is highly desirable for integrated pest management. Here, we evaluated under laboratory conditions the effect of azadirachtin- and oxymatrine-based formulations on each development stage of T. evansi and on the adult stage of the predatory mite Phytoseiulus longipes, the single promising predator of this pest. We also assessed the residual effect of these biopesticides on T. evansi under laboratory conditions on leaflets excised from treated tomato plants maintained in a screen-house 1, 5, and 10 days after application. Azadirachtin-based formulations were effective in controlling T. evansi immature stages. Oxymatrine-based treatments controlled T. evansi immatures and adult females faster than azadirachtin-based treatments. Both biopesticides had no effect on T. evansi eggs, but oxymatrine-based treatments were highly efficient on newly hatched T. evansi larvae. Oxymatrine displayed residual activity that controlled T. evansi up to 10 days after application. Azadirachtin formulations caused lower mortality of P. longipes adults (8–28%) and slightly reduced fecundity (24.8–56.1%). In contrast, oxymatrine treatments caused higher mortality (60–88%) of the predator and reduced substantiality its fecundity (73.1–90.7%). Our findings suggest that Azadirachtin and oxymatrine provide effective control of T. evansi. Azadirachtin may be relatively safer to the predatory mites whereas oxymatrine should be used with caution, to avoid suppression of P. longipes.

Optimizing long-acting acaricide use for integrated tick management of Rhipicephalus australis-infesting cattle in New Caledonia.

The tick Rhipicephalus australis, formerly known as Rhipicephalus microplus, is the most economically important ectoparasite of livestock in New Caledonia, affecting cattle health and production. Decades of control attempts based on the application of chemical acaricides have exerted a strong selective pressure on R. australis populations, some of which have evolved resistance to these treatments. Research to develop integrated tick control programs is now focused on decreasing applications of chemicals. This study reports the implementation of a method of pasture and herd management involving minimal strategic use of long-acting acaricides, here defined as those having substantial efficacy against larvae for several weeks. Diverse parameters concerning the utilization of long-acting acaricides in association with pasture and herd management on 21 New Caledonian farms over a 5-year period were analyzed to optimize their strategic use. Longer larval acaricidal effect was achieved with a commercial pour-on formulation of fluazuron than with a commercial injectable (subcutaneous) formulation containing 3.15% ivermectin. Pasture and herd management allowed an increase in the delay between a long-lasting acaricide application and the subsequent acaricide treatment from 11.0weeks to 17.7weeks. However, if ticks were detected and reported by producers on the day of a long-acting acaricide application, the delay to the following treatment was reduced from 18.5weeks to 11.2weeks. The impact of a long-acting acaricide treatment on larval populations in pastures was greatest with a stocking rate of 5 animals per hectare grazing during 1week. These results provide science-based evidence to cattle producers for adaptive integrated tick management in order to delay the development of acaricide resistance.

Toxicity of chitosan derivatives to Varroa destructor (Anderson and Trueman) and their effects on immune gene expression in honey bees

Varroasisis caused by Varroa destrucor (Anderson and Trueman) is considered the most dangerous honey bee disease. V. destructor mites parasitize both brood and adults, causing considerable losses to the colony population. The control of Varroa mites is highly dependent on the application of synthetic acaricides, however, acaricide resistance can develop. To eliminate the risk of Varroa mite resistance and to reduce residues in hive products, organic-based substances for Varroa mite control are being applied. In the present study, the acaricidal activity of N-alkyl and O-acyl chitosan derivatives against Varroa mites and their side effects on honey bees have been evaluated. Chitosan has been extracted from the corpses of honey bees. The yield, degree of deacetylation, and molecular weight of chitosan from the chitin of honey bee corpses were determined as 89%, 90%, and 20 kDa, respectively. Varroa mite mortalities were observed between 6.28-84.38% and 0.00-90.47% by N-alkyl and O-acyl chitosan derivatives, respectively. The best derivatives against Varroa mite were N-(3-phenylbutyl)chitosan (NAC-5) and O-(heptanoyl)chitosan (OAC-4). The results showed that different lethal concentrations of NAC-5 and OAC-4 had side effects against honey bees less than 26%. No significant difference was found between honey bee mortalities at 24, 48, and 72 hours post-treatment, while mortalities significantly differed between 4, and 24 h post-treatment. Immune gene expression in honey bees exposed to a lethal concentration of NAC-5and OAC-4 showed that the expressions of AmHym, AmBask, and AmSpz were significantly lower compared with those of control honey bees.

Evaluation of two predatory mites and acaricide to suppress Tetranychus urticae (Acari: Tetranychidae) on strawberry

BackgroundThe two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a major pest of strawberry. It was necessary to control this mite pest that can reducing the quality and quantity of the fruits. In this regard, the effect of ZORO acaricide, Neoseiulus californicus (McGregor) and Amblyseius swirskii Athias-Henriot for suppressing the naturally occurring T. urticae populations on three strawberry cultivars were investigated.ResultsThe two predatory mites and ZORO treatments significantly suppressed the populations of T. urticae below the control in all tested cultivars. In most cases of the current study, significantly lower numbers of T. urticae were generally observed in ZORO and N. californicus treatments compared to A. swirskii treatment. In all cultivars, the overall mean of reduction percentages of T. urticae populations in N. californicus and ZORO treatments were not statistically different, and all were significantly higher than that in A. swirskii treatment.ConclusionThe present results suggested that the release of N. californicus and the application of ZORO acaricide could be promising strategies for controlling T. urticae on strawberry, although the release of N. californicus appears to be more competent tactic than ZORO acaricide.

Spatial surveillance and risk factor assessment of ixodid ticks in cattle population of Himachal Shivalik hill zone of North-Western Himalayas

ABSTRACT The present study aimed at assessing the epidemiology and associated risk factors of ixodid ticks from Shivalik hill zone of Himachal Pradesh, India. A total of 602 cattle of different age, breeds, and sex were screened for the occurrence of ixodid ticks from six districts from March, 2019 to February, 2020. The associated data were recorded for the risk factor assessment. The overall tick prevalence was recorded to be 66.4%. Three tick species were found prevalent viz., Rhipicephalus (Boophilus) microplus (68.4%), Rhipicephalus (Boophilus) annulatus (30.85%), and Hyalomma anatolicum anatolicum (0.74%). The highest prevalence was recorded during the monsoon season (74.9%) (OR: 1.25; 0.65–1.86) followed by summer (65.3%) and lowest in winter season (59.4%) (OR: 0.64; 0.26–0.79). Agewise, tick infestation was observed to be highest in age group >1 year (76.5%) (OR: 6.37; 3.32–12.21) followed by age group >6 months–1 year (38.8%) (OR: 9.09; 4.67–17.69) and the lowest in ≤6 months age (29.3%). The prevalence rate was found to be more in female cattle (71.6%) in comparison to males (23.4%). Breedwise, the highest tick infestation was observed in cross-bred Jersey (69.8%) (OR: 3.51; 1.59–7.76) followed by cross-bred Holstein Friesian (69.6%) (OR: 0.95; 0.51–1.75) and lowest in indigenous cattle (45.0%). The risk factors related to management practices revealed that the prevalence of ixodid ticks was significantly (P < 0.05) less when the animals were kept in pucca sheds with acaricide application done both on body and shed with reapplication in 3 months. The odds of tick infestation were high in cattle population in Solan (OR: 2.29; 1.05-5.02) and least in Hamirpur in comparison to Kangra region (reference district) when the regression analysis of the risk factors associated with tick prevalence was studied. The current study represents the first report determining the epidemiological status of ixodid ticks in Shivalik hill zone region and findings of the study would provide a basis for generating new and effective control strategies for management the management of ticks in cattle population of the region.

Mechanisms and management of acaricide resistance for Tetranychus urticae in agroecosystems

The two-spotted spider mite, Tetranychus urticae Koch, is a constant threat to sustainable production of numerous economically important crops globally. Management of T. urticae is heavily reliant on the application of synthetic acaricides. However, T. urticae has rapidly developed resistance to most of the acaricides available for its control due to its very broad host plant range, extremely short lifecycle, high fecundity, arrhenotokous parthenogenesis, and overwintering strategy. Despite the recent progress in identifying genetic changes/markers associated with resistance toward some commonly used acaricides for T. urticae, there is still limited studies that select and apply these markers in field populations to guide sustainable pest management strategy design. Temporal and spatial characterization of acaricide-resistant phenotypes and their underlying mechanisms are crucial for the design and implementation of successful and sustainable integrated mite management programs. This review highlights the current acaricide resistance status of field-collected T. urticae populations and the underlying molecular mechanisms of resistance. Our review found that some genetic mutations in target sites and/or overexpression of metabolic genes confer resistance in geographically exclusive populations, while some resistance markers appear to be specific to populations at biogeographical areas. Thus, there is a need for locally based coordinated efforts to understand the mechanisms of resistance present in endemic T. urticae populations. Moreover, we discuss a prospective template for designing an effective acaricide resistance management program within various agroecosystems.

Effects of white-tailed deer habitat use preferences on southern cattle fever tick eradication: simulating impact on \u201cpasture vacation\u201d strategies

BackgroundRhipicephalus (Boophilus) annulatus and Rhipicephalus (Boophilus) microplus (southern cattle fever tick; SCFT), collectively known as cattle-fever ticks (CFTs), are vectors of protozoal parasites (Babesia bigemina and Babesia bovis) that cause bovine babesiosis (also known as cattle fever). One traditional strategy for CFT eradication involves the implementation of a “pasture vacation,” which involves removing cattle (Bos taurus) from an infested pasture for an extended period of time. However, vacated pastures are often inhabited by wildlife hosts, such as white-tailed deer (WTD; Odocoileus virginianus), which can serve as alternate hosts for questing CFTs. We hypothesized that the distribution of host-seeking larvae among habitat types post-pasture vacation would reflect habitat use patterns of WTD, and in turn, affect the subsequent rate of pasture infestation by CFT.MethodsWe adapted a spatially explicit, individual-based model to simulate interactions among SCFT, cattle, and WTD as a tool to investigate the potential effects of WTD habitat use preferences on the efficacy of a pasture vacation. We parameterized the model to represent conditions typical of rangelands in south Texas, USA, simulated a 1-year pasture vacation under different assumptions regarding WTD habitat use preferences, and summarized effects on efficacy through (1) time post-vacation to reach 100% of pre-vacation densities of host-seeking larvae, and (2) the ecological conditions that resulted in the lowest host-seeking larval densities following pasture vacation.ResultsLarval densities at the landscape scale varied seasonally in a similar manner over the entire simulation period, regardless of WTD habitat use preferences. Following the removal of cattle, larval densities declined sharply to < 100 larvae/ha. Following the return of cattle, larval densities increased to > 60% of pre-vacation densities ≈ 21 weeks post-vacation, and reached pre-vacation levels in less than a year. Trends in larval densities in different habitat types paralleled those at the landscape scale over the entire simulation period, but differed quantitatively from one another during the pasture vacation. Relative larval densities (highest to lowest) shifted from (1) wood/shrub, (2) grass, (3) mixed-brush during the pre-vacation period to (1) mixed-brush, (2) wood/shrub, (3) grass or (1) wood/shrub, (2) mixed-brush, (3) grass during the post-vacation period, depending on WTD habitat use preferences.ConclusionsBy monitoring WTD-driven shifts in distributions of SCFT host-seeking larvae among habitat types during simulated pasture vacation experiments, we were able to identify potential SCFT refugia from which recrudescence of infestations could originate. Such information could inform timely applications of acaricides to specific refugia habitats immediately prior to the termination of pasture vacations.Graphical