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1.
A case control study was carried out within a cross-sectional survey designed to investigate the management by Queensland dairy farmers of the cattle tick Boophilus microplus. Although 199 farmers were surveyed, data on acaricide resistance were only obtained from 66 farms. Multiple models were used to predict the probability of acaricide resistance associated with 30 putative risk factors. The region of the state in which the farm was located and the frequency of acaricide application were consistently associated with acaricide resistance. The risk of resistance to all synthetic pyrethroids (Parkhurst strain) was highest in Central Queensland and increased when more than five applications of acaricide were made in the previous year, when spray races were used and when buffalo fly treatments with a synthetic pyrethroid were applied frequently. The probability of resistance to amitraz (Ulam strain) was highest in Central Queensland, increased when more than five applications of acaricide were made in the previous year, and decreased on farms when a hand-spray apparatus was used to apply acaricides to cattle. The probability of resistance to flumethrin (Lamington strain) was highest in the Wide Bay-Burnett region.  相似文献   

2.
We document the presence of a Rhipicephalus microplus tick population resistant to acaricides (organophosphates (OP), synthetic pyrethroids (SP), amitraz) and macrocyclic lactones (ML) (ivermectin). Engorged females of R. microplus were collected from a cattle farm in Veracruz, Mexico, to evaluate acaricide and ivermectin resistance. The modified larval packet test (LPT) was used to detect OP (chlorpiriphos and diazinon) and SP (flumethrin, deltamethrin and cypermethrin) resistance and the larval immersion test (LIT) to detect resistance to amitraz and ivermectin. Both, LPT and LIT were performed twice at different times with different collected samples. Mortality data with ivermectin were subjected to probit analysis to obtain lethal concentrations and resistance ratios (RR) using an ivermectin-susceptible strain (Deutch) as a reference. The R. microplus population showed resistance to all acaricides tested, with different mortalities at the discriminate dose: chlorpiriphos (1%), diazinon (24.2%), flumethrin (92.8%), deltamethrin (94.2%), cypermethrin (98.0%) and amitraz (1.5%). The studied tick population also showed resistance to ivermectin with a resistance ratio at 99% of 9.58 and 6.52 in the first and second evaluation, respectively. We report for the first time a R. microplus population in Mexico with different levels of resistance to OP, SP, amidines (Am) and ivermectin. The uncontrolled use of these products in the study area may promote the complete failure of tick control within a short period of time.  相似文献   

3.
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4.
As part of a continuing programme to aid in the development of new acaricides, the potentials of three synthetic pyrethroids, permethrin, cypermethrin and decamethrin, were assessed against a range of resistant strains of the cattle tick (Boophilus microplus). The compounds were shown to be acaricidal, with decamethrin the most effective, giving efficient control of susceptible and organo-phosphorus resistant strains of the cattle tick at concentrations as low as one fifth of those previously used for any commercial acaricide. However higher concentrations were required for satisfactory control of the DDT-resistant strain. Permethrin-selection of a field strain containing a low percentage of DDT-resistant ticks led to rapid development of resistance to a level equivalent to that of the DDT-resistant strain. Further selection increased resistance to permethrin to a higher level than that shown in the DDT-resistant strain. This increased resistance to permethrin appears to be restricted mainly to this compound and is not associated with a marked increase in resistance to cypermethrin, decamethrin or DDT. The potential of organo-phosphorus compounds to potentiate the pyrethroids when the two classes of compounds are used as mixtures against the pyrethroid-resistant and susceptible strains was confirmed.  相似文献   

5.
Efficacy trials with flumethrin 1% pour-on were conducted in 9 different areas in 3 southern and central African countries against Amblyomma hebraeum and A. variegatum on cattle. A dose volume of 10 ml/100 kg body mass applied at bi-weekly intervals provided excellent control of both tick species on their predilection sites, irrespective of locally and seasonally high tick pressure. The trial results demonstrate clearly that this new concept of tick control can be effectively applied in commercial and traditional cattle husbandry situations.  相似文献   

6.
A cross-sectional study was carried out in order to investigate the association between management risk factors and the prevalence of organophosphate (OP) and synthetic pyrethroid (SP) resistance in Boophilus microplus ticks in Yucatan State, Mexico. Ninety-eight cattle ranches were randomly selected and a sample of 20-30 engorged female B. microplus ticks was collected at each. The modified larvae packet test was used to detect OP and SP tick resistance. A questionnaire was administered on each ranch. For risk factors, four reference types of response were used: Tuxpan (resistant to coumaphos, chlorfenvinphos and diazinon), Parkhurst (resistant to flumethrin, deltamethrin and cypermethrin), Lamington (resistant to flumethrin in absence of deltamethrin and cypermethrin) and Marmor (resistant to flumethrin and cypermethrin in absence of flumethrin). A primary screening was performed using 2 x 2 contingency tables of exposure variables. All variables with p < or = 0.20 were analyzed by a logistic regression. The prevalence of B. microplus resistance to OP and SP groups were 83.70% and 66.32%, respectively. The prevalence for a single chemical compound was: diazinon (80.60%), coumaphos (45.90%), chlorfenvinphos (35.70%), flumethrin (63.28%), deltamethrin (61.22%), and cypermethrin (59.18%). The prevalence type of response was: Tuxpan (34.16%), Parkhurst (58.16%), Lamington (4.08%), and Marmor (4.08%). The use of a different tick control program was the risk management factor associated with the Parkhurst type of response. It is concluded that the prevalence of cattle ranches with B. microplus resistant to OPs and SPs in Yucatan, Mexico, is a current problem, and a treatment interval of > or =6 times/year and use of a tick control program (macrocyclic lactones and pasture burn) different from standard recommended programs are risk factors associated with the Parkhurst type of response.  相似文献   

7.
Chen AC  He H  Davey RB 《Veterinary parasitology》2007,148(3-4):379-383
The mode of action of amitraz is thought to be its toxic effects on a receptor for a neuromodulator, octopamine. Resistance could arise from modifications of this receptor so that it would not be affected by amitraz. A putative octopamine receptor cDNA was cloned and sequenced from a cattle tick in Australia. However, when the sequence was compared between Australian strains of amitraz-susceptible and resistant ticks, no differences were detected. We have sequenced this putative octopamine receptor gene in tick strains from America. The American ticks have a sequence almost identical to that of the Australian ticks with no deletions or additions in the open reading frame. In a Brazilian strain and a Mexican strain that are very resistant to amitraz, there are two nucleotide substitutions that result in amino acids different from all the susceptible strains. Discovery of these mutations only in amitraz-resistant ticks provides the first evidence for the possibility of an altered pesticide target site as a mechanism of amitraz resistance in ticks.  相似文献   

8.
The response of sheep scab mites to pyrethroid insecticides and organophosphate compounds was studied in vitro with the objective of finding a simple test for detecting insecticide resistance in scab mites. Psoroptes cuniculi from rabbits or P. ovis from sheep were enclosed in small 'tea bags' made from heat sealable paper prior to dipping in insecticide. Mites failed to die 24 h after a 1 min dip in working concentrations of insecticidal sheep dips. With flumethrin a variety of different conditions were tested but most failed to improve the efficacy of flumethrin. It is suggested with freshly collected mites pyrethroids may be taken up by ingestion.  相似文献   

9.
Rhipicephalus (Boophilus) microplus is an important cattle pest in Uruguay, and the law regulates its control. It is resistant to organophosphates, synthetic pyrethroids and, as recently discovered, to fipronil. Resistance to macrocyclic lactones (MLs) and amitraz have not been documented; however, veterinarians and farmers have reported treatment failures. The objective of the present work was to study the susceptibility of cattle tick strains from different Uruguayan counties to ivermectin (IVM) and fipronil by using the Larval Immersion Test (LIT). The Mozo strain was used as the susceptible reference strain. From 2007 to 2009, twenty-eight tick populations were collected from different cattle farms with and without history of IVM or fipronil use. A probit analysis estimated dose-mortality regressions, lethal concentrations (LC), and confidence intervals. The resistance ratio (RR) was determined at the LC(50) and LC(90) estimates. To classify a tick population in relation to resistance, three categories based on a statistical analysis of LC and RR between field populations and Mozo strains were defined: susceptible (no differences), incipient resistance (differences and RR(50)<2) and resistant (differences and RR(50)≥2). Eighteen field populations were tested with IVM and five of them presented a RR(50) range between 1.35 and 1.98 and the LC(50/90), which is statistically different from the Mozo strain (incipient resistance). However, the RR(90) increases ≥2 in four of the populations, confirming that tick resistance to IVM is emergent. The low RR values obtained could be a result of a low frequency of treatments with IVM. Twenty-seven tick populations were tested with fipronil and six were diagnosed as resistant according to the LIT. Cross-resistance was not observed between fipronil and IVM on these tick populations. The current study presents different R. (B.) microplus populations with an incipient resistance to IVM, and indicates that the fipronil tick resistance is restricted to certain areas in Uruguay.  相似文献   

10.
Objective To determine the efficacy of zeta-cypermethrin in controlling buffalo fly ( Haematobia irritans exigua ).
Design Five field trials in northern and central Queensland.
Procedure Zeta-cypermethrin pour-on at 2.5 mg/kg, spray at 62.5 ppm, deltamethrin pour-on and pour-on vehicle were applied to groups of 20 cattle. Buffalo fly counts were conducted three times before treatment and 3, 7, 14, 21, 28 and 35 days after treatment.
Results In central Queensland where synthetic pyrethroid resistance in buffalo fly populations was rare, 2.5 mg/kg of zeta-cypermethrin pour-on gave good control of buffalo fly for 4 weeks and was better than a deltamethrin product. A zeta-cypermethrin spray used at 62.5 ppm gave 14 days control. In far-north Queensland where resistance to synthetic pyrethroids and heavy rain was common, the maximum period of efficacy of zeta-cypermethrin pour-on was reduced to 2 weeks.
Conclusion In areas where there is low resistance to synthetic pyrethroids among buffalo flies, zeta-cypermethrin pour-on can be expected to give good control for 4 weeks.  相似文献   

11.
SUMMARY: A survey was made from late 1976 to late 1977 to determine the extent of resistance to acaricides in the cattle tick Boophilus microplus in Queensland. Questionnaires and requests for samples of ticks were forwarded to more than 900 randomly selected stock owners in the tick infested area which had been divided into 4 regions, Far North, Coastal North, Coastal Central and South East. The response measured by the number of tick samples tested was 43%. The prevalence of resistance to organophosphorus (OP) compounds was highest in South East where 96% of the farms had OP-resistant ticks and 95% had the Biarra strain and lowest in Far North where 12% of the farms had OP-resistant ticks and 10% had the Biarra strain which was the predominant one in all regions. The highest percentages of the Ridgelands strain (35%) and the Tully strain (30%) occurred in Coastal North. The South East had the highest percentage of Mt Alford (30%).
Although chlorinated hydrocarbons were banned for use in control of ticks in 1962, 49% of the farms in South East had some ticks resistant to dieldrin but in Far North it was only 2%. DDT-resistant ticks, which because of cross resistance to synthetic pyrethroids will affect the future use of this group, were present on 8% of the farms in both Coastal North and Coastal Central and 3% in South East and Far North.
No resistance to the amidines, chlordimeform, chloromethiuron or amitraz was found.  相似文献   

12.
OBJECTIVE: To establish the cost to the Queensland dairy industry of cattle tick infestation and its control, excluding the costs incurred from control measures directed specifically at tick fever and morbidity and mortality arising from tick fever. STUDY DESIGN: Economic models are described that have been based on empirical data relating to liveweight and milk yield loss, and on a survey of control practices and tick infestation. The first two models were designed to estimate costs of control and losses resulting from tick infestation on a single dairy farm. The third model developed estimates of the cost of tick infestation for each of four regions within the tick-infested area of Queensland. RESULTS: The overall cost to the Queensland dairy industry of the cattle tick (excluding the costs associated specifically with tick fever) and based on 1998 management practices, was $4,096,000 per annum. About 49% of this cost was related to the costs of control and 51% to losses in production. CONCLUSION: Cattle tick infestation represents a significant impost on dairy producers in Queensland, and although the actual cost will change as deregulation results in economic changes in the industry, infestations of ticks will continue to be expensive to control.  相似文献   

13.
The numbers of bush ticks, Haemaphysalis longicornis, on Bos taurus steers in south east Queensland was recorded regularly from July 1971 until January 1974. The steers had no prior exposure to the tick. The parasitic tick population was large during the first year, but declined to low levels in the second and third years, apparently as a result of the steers acquiring resistance to tick feeding.  相似文献   

14.
While resistance against many other classes of acaricides has been described, products containing benzoylphenyl urea are currently still successfully used against the pesticide-resistant blue tick (Boophilus decoloratus) in South Africa. In order to assess any adverse impact of these tickicides on the important dung beetle (Coleoptera: Scarabaeidae) fauna, a bioassay was undertaken on the ecotoxicological effects of a fluazuron (benzoylphenyl urea) pour-on formulation (Acatak) on the survival and reproduction of the African dung beetles species Onthophagus gazella (Fabricius). The experiment yielded no significant differences in adult or larval survival, egg production, fecundity and fertility between the control and treatment group following three beetle generations over. These results suggested that treatment of cattle with the fluazuron pour-on formulation Acatak was not detrimental to the selected dung beetle species in any notable way.  相似文献   

15.
A strain of Boophilus decoloratus, resistant to fenvalerate, was subjected to larval immersion, adult immersion and stall tests using the following classes of ixodicides: organochlorines, organophosphates, a diamidide and pyrethroids. A susceptible reference strain of B. decoloratus was used for comparative purposes. The results indicated a high level of resistance to DDT and camphechlor, slight tolerance to dioxathion, chlorfenvinphos and pirimiphos ethyl, full susceptibility to bromophos ethyl and amitraz, but marked resistance to cyhalothrin, cypemethrin, deltamethrin and flumethrin. This marked resistance in the strain therefore appears to be widespread within the pyrethroid group of chemicals and may have developed as a result of organochlorine cross-resistance.  相似文献   

16.
OBJECTIVES: To compare the features of farms on which the exposure of young cattle to tick fever organisms is sufficient to ensure that immunity is high and the risk of clinical disease is low (endemic stability) with those of farms on which exposure is insufficient to induce widespread immunity (hence without endemic stability); to examine the relationships between the management of ticks and tick fever, and endemic stability to Babesia bovis, B. bigemina and Anaplasma marginale. DESIGN: Cross-sectional study of 874 cattle between the ages of 6 and 15 months on 64 dairy farms, from three centres in south-eastern Queensland (Mutdapilly, Dayboro and Kenilworth) and one centre in far-north Queensland (Malanda). PROCEDURE: Blood samples collected from between 5 and 20 calves from each farm were submitted for serological assay to determine exposure to B. bovis, B. bigemina and A. marginale. A questionnaire about the farm characteristics and the management of ticks and tick fever was completed with each farmer. RESULTS: On 73% of farms, confirmed clinical cases of tick fever were recalled by the farmer, indicating that tick fever was a threat on most farms. The majority of herds in the study (54 of 64) did not have sufficient numbers of seropositive animals aged between 6 and 15 months to have a low risk of tick fever. Region had an effect on the likelihood of endemic stability for all tick fever organisms. Cattle near Malanda in Far-north Queensland were more likely to be seropositive to B. bovis and B. bigemina. The method, strategy and intensity of tick control were not related to the likelihood of endemic stability when the effect of region was considered. The decision to leave a few ticks on cattle in an effort to induce endemic stability did increase the likelihood of endemic stability to A. marginale. However, in practical terms, it was ineffective, because only 26% of these farms had endemic stability against all three organisms. CONCLUSIONS: Given the low proportion of farms that have endemic stability to the tick fever organisms and the high likelihood of clinical disease, vaccination is recommended to protect dairy cattle from tick fever throughout the tick infested area of Queensland. However, further work is required to determine the economic value of vaccination, taking into account the costs of vaccination, of outbreaks and the protective value of vaccination.  相似文献   

17.
The effects of six new synthetic carbamates on fully engorged females of four Rhipicephalus microplus strains (one reference strain susceptible to conventional ixodicides, two strains multiresistant to ixodicides and one tick field isolate) were compared. In addition, the effect of two other new synthetic carbamates was tested on larvae from the same strains. The first six tested carbamates reduced egg laying and inhibited egg hatching in the four studied strains (P < 0.05). Compared with untreated females, the eggs produced by the treated engorged female ticks of all strains had a dark, dry, opaque appearance and were less adherent. The remaining two tested carbamates induced larval mortality in all of the evaluated strains. The three studied R. microplus strains displayed 50% resistance ratios (RR50) of less than 2 when compared to the susceptible reference strain. These results demonstrate that both carbamates with a larvicidal effect and carbamates that inhibit egg laying and embryo development are efficacious against tick strains that are resistant to commercial ixodicides, no cross resistance was observed.  相似文献   

18.
The efficacy of a flumethrin 1% pour-on (Bayticol, Bayer AH) was evaluated against natural infestations of ticks on cattle on a dairy farm in Ethiopia during 1997/98. The cattle, (n = 92), which were Friesian/ Zebu crosses, were heavily infested with Boophilus decoloratus. Dry cows (n = 8) were randomly selected and allocated either into a treatment or a control group. Flumethrin 1 % pour-on was applied to the treatment group according to the manufacturer's recommendation, i.e. along the dorsal mid-line from the head to the base of the tail. Ticks were counted and identified in situ on treated and control animals. When the total tick counts of the treated group were similar to those on the control, the trial was discontinued. Excellent results were achieved with flumethrin against heavy tick infestations. There was a rapid kill after 24 h post-treatment, and from day 4 onwards 100% control was achieved and maintained for a further 29 days. The results obtained indicate that there was a significant difference between the mean tick counts of the control group compared with those of the treatment group (P < 0,05). The evidence presented here suggests that the flumethrin 1 % pour-on may be applied at 45 day intervals and should provide effective protection against the economically important ticks if it is used at the recommended dosage rate and applied correctly.  相似文献   

19.
Resistance to synthetic pyrethroids (SP) was first recorded in buffalo flies in Australia in 1980, associated with previous use of DDT and fenvalerate. By the 1990s, resistance was widespread. Resistance to SP in the related horn fly of the Americas is associated with kdr and super-kdr mutations in a gene encoding for a voltage-gated sodium channel. We describe 7-20-fold resistance to SP in buffalo flies from south-east Queensland, present evidence of flies that are heterozygous resistant at the kdr locus and show an increase in the frequency of the resistant allele 1 month after treatment of cattle with SP.  相似文献   

20.
Acaricide resistance of the cattle tick Rhipicephalus (Boophilus) microplus is widespread in most of the countries where this parasite is present. Bioassays are used to diagnose the level and pattern of resistance in tick populations. In the present study, we describe a detailed protocol of the Larval Tarsal Test (LTT) using simplified equipment and data on the resistance of 17 tick field populations originating from 5 Brazilian states. Nine acaricidal compounds from 5 major classes were tested: organophosphates (OP), synthetic pyrethroids (SP), macrocyclic lactones (ML), phenylpyrazols (PYZ) and amidines. For comparison, four of the tick populations were also tested with the Larval Packet Test (LPT) with one compound per class. The most common resistances were to SP, amitraz and OP, with frequencies of 94%, 88% and 82%, respectively. Resistance to PYZ was also found to be widespread (65%), suggesting a rapid development of fipronil resistance in Brazil. One case of ML resistance and 2 cases of suspected ML resistance were identified with the LTT. The LTT led to higher resistance ratios to all compounds than the LPT, reflecting its high sensitivity to detect resistance. Finally, the LTT allowed testing a larger number of compounds and doses with reduced labour in comparison to the LPT and turned out to be a reliable bioassay to detect resistance in field populations.  相似文献   

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