Evaluation of a Pour-on Formulation of Fipronil Against Boophilus Annulatus (Acari: Ixodidae) Under Natural South Texas Field Conditions

A long-term field study (60 consecutive weeks) was conducted to determine whether a Boophilus annulatus (Say) population could be eradicated through repeated applications of a 1% pour-on formulation of fipronil on cattle held in an infested pasture. Animals treated repeatedly over time (seven applications) were infested with significantly fewer (p < 0.05) female ticks (5 mm in size) than untreated animals in all except one of the 57 weekly tick counts conducted after the first treatment was applied. As the number of treatments increased over time, there was a progressive decrease in the number of instances in which engorging females were observed on the treated cattle. Tick numbers obtained from sentinel cattle placed in pasture with untreated and treated cattle at various intervals throughout the study indicated that a single fipronil treatment had no observable adverse effect on the field tick population. However, after two treatments had been applied, there were always dramatically fewer ticks obtained from sentinel animals placed with treated cattle than were observed on sentinel animals placed with untreated cattle. Furthermore, tick numbers obtained from sentinel cattle placed with treated cattle over time indicated that the tick population in the pasture declined by stages. While a single treatment had no effect on the tick population, the application of two to four fipronil treatments at various intervals dramatically reduced the tick population, even though substantial numbers of females were still present on the sentinel animals. Ultimately, the application of five to seven fipronil treatments resulted in an extremely low tick population in the pasture, although total eradication of the population was not achieved during the study. The mean weight gain of treated animals was significantly higher (p < 0.05) than untreated animals during the study, indicating that the fipronil treatments had a highly beneficial impact on weight gain production.     

The effects of the bont tick, Amblyomma hebraeum, on milk production of Sanga and Sanga x Brahman cattle

Abstract. The effects of adults of the bont tick, Amblyomma hebraeum on the milk production of Sanga and Sanga x zebu (Brahman) cattle were measured over a period of 11 weeks in the lowveld of Zimbabwe in the summer of 1986. Four groups of lactating cows, consisting of two breeds, each divided into a high and low tick treatment, were exposed to very low or high challenges of ticks and their milk production measured by weighing their calves before and after suckling. The liveweight gains (LWG) of the calves were also measured.
Tick burdens on the infested groups averaged around fourteen engorging females of A.hebraeum per day, which amounted to infestations of about 150 adult ticks. That is greater than most observed field infestations. This caused no significant reduction in milk yield or calf growth over the whole period, provided the teats of the dams had not been damaged by ticks. Mismothering occurred when teats were damaged. No breed differences were observed so all data was pooled for further analysis. Average calf LWGs of the high tick groups were reduced by 2.2kg (P < 0.01) during one 4-week period but overall the 3.9 kg difference in LWG of the tick treatment groups was not quite significant (P < 0.10). Although there was a poor relationship between tick numbers and reduced milk yield or calf LWG, the effects were always in the direction expected. The effects averaged 6 ± lOg reduction of milk and 2.6 ± 1.8g loss of LWG of calves for every female tick that engorged. It was concluded that milk production is not an important consideration when estimating the losses in production caused by A.hebraeum on Brahman x Sanga or Sanga breeds of cattle. Losses due to teat or udder damage could be much more important and need to be quantified.     

Efficiency and cost of strategic use of acaricide for tick control in N'Dama cattle in The Gambia

The efficiency of strategic and strategic/selective applications of flumethrin spray formulation for controlling ticks were assessed, respectively, in two groups of fourteen N'Dama cattle (Group S and Group S/S) by comparison of the number of feeding ticks with thirteen untreated N'Dama cattle (Group U) over a period of 11 months (June 1996 to April 1997). During the expected peak of tick abundance, acaricide was applied fortnightly on the whole body in animals in Group S and only on the most infested body areas in cattle in Group S/S. Weight changes and skin lesions, directly associated with tick attachment, were recorded in cattle in the three groups. The costs of the two tick control schemes were estimated. Maximum level of ticks, all species together, feeding on cattle was observed in the rainy season. Both in Group S/S and Group S, cattle carried a lower (P < 0.001) number of feeding ticks than animals in Group U over the whole study period. Percentage of tick control, over the entire period of tick investigation, was satisfactory in both acaricide-treated groups, reaching 61.2 and 75.2% in Groups S/S and S, respectively. However, the proportion of control varied according to tick species or genus. Significantly lower prevalence of skin lesions was observed on the ano-genital and udder region in cattle in Group S/S (P < 0.05) and Group S (P < 0.01) in comparison with cattle in Group U. Mean amount of acaricide solution used and relative estimated cost of treatment in cattle in Group S/S were, respectively, 25- and 14-fold lower than those in cattle in Group S. At the end of the study, animals in Groups S/S and S were, respectively, 7.2 and 15.9 kg heavier than animals in Group U. The difference was statistically significant (P < 0.02) only between Groups S and U. However, the efficiency, low cost and derived benefits of the strategic/selective acaricide application scheme indicated that it might be the most cost effective.     

Detection of Theileria annulata by the PCR in ticks (Acari: Ixodidae) collected from cattle in Mauritania

We report on the detection of Theileria annulata in infected Hyalomma ticks by the PCR using primers derived from the gene encoding the 30 kDa major merozoite surface antigen (Tams1–1). No inhibition of the PCR was observed and as little as 0.1 pg of parasite DNA, corresponding to 12 sporozoites, could be detected in non-infected tick DNA samples, spiked with T. annulata genomic DNA. Hyalomma dromedarii ticks, fed on a calf experimentally infected with T. annulata, were used to validate the PCR further. The infection rate in the adult ticks, fed as nymphs during the febrile reaction, was high (62%), dropped to zero for 1 day in tick batches that engorged after treatment with ButalexTM and increased to 30% 2 days later and 38% of the ticks acquired the infection after feeding as nymphs during a carrier state piroplasm parasitaemia of less than 0.1%. As an internal control, 16S tick rDNA sequences could be amplified from T. annulata-negative tick samples. Finally, 202 adult ticks from Mauritania, collected from zebu cattle carrying low levels of Theileria piroplasms, were tested by the PCR. Thirty-eight out of 52 (73%) and 17 out of 30 (57%) H. dromedarii from the Gorgol and Trarza regions, respectively and two out of 30 (7%) Hyalomma marginatum rufipes from the Gorgol region were positive. Hyalomma marginatum rufipes, Rhipicephalus evertsi evertsi and Rhipicephalus guilhoni from the Trarza region were negative. These findings confirm that H. dromedarii is the main vector of T. annulata in Mauritania and that the PCR is a useful method of determining the infection rates in ticks collected from cattle carrying low levels of T. annulata piroplasms.     

Status of Haemaphysalis tick infestation in domestic ruminants in Iran

The geographical distribution and ecological preferences of Haemaphysalis in domestic animals in Iran were studied 4 times a year from April 2003 to March 2005. A total of 1,622 ixodid tick specimens were collected from 3 different zones. Among them, 108 (6.7%) Haemaphysalis ticks, consisting of 6 species, were identified; H. punctata (3.4%), H. parva (0.5%), H. sulcata (0.6%), H. choldokovskyi (1.7%), H. concinna (0.06%) and Haemaphysalis sp. (0.6%). H. punctata was the most abundant species, whereas H. concinna was the rarest species collected in humid and sub-humid zones on cattle, sheep and goats. H. choldokovskyi was principally collected from sheep and goats grazed in cold mountainous areas. The infested areas consisted of Caspian Sea (Guilan, Mazandaran, Golestan, and central provinces), mountainous (Azarbaiejan, Ardebil, Kohgilouyeh, and Kordestan) and semi-dessert (Khorasan, Semnan, Kerman, Sistan, and Baluchestan) zones. The Caspian Sea zone (23.6%) was the most highly infested region. The results show that various species of Haemaphysalis ticks infest domestic ruminants in Iran and each tick species show characteristic geographical distributions.     

Cattle lice (Anoplura, Mallophaga) in New York: seasonal population changes, effects of housing type on infestations of calves, and sampling efficiency

A year-long survey was made of commercial dairy herds in New York for cattle lice (Anoplura and Mallophaga). All herds were infested with lice. The cattle bitting louse, Bovicola bovis (L.), accounted for about 90% of the observed infestations; infestations of mature animals were most common during the winter months, especially March (26% infested); and infestation rates of calves were high (30-45%) from January through June. Cows that were housed in stanchion barns were about twice as likely to be infested (24.7%) as were those in free stalls (11.1%). Calves housed in individual outdoor hutches had substantially lower infestation rates (4.5%) than calves maintained inside barns in collective stalls and pens (46.0%).     

Prevalence of hard tick infestations in cattle of Mizoram,India

The present study was conducted to determine the prevalence of hard tick infestations in cattle of Mizoram from April 2017 to March 2018. The prevalence of hard tick infestations was studied in relation to sex and age of animals and seasonal changes in a year. Cattle of selected places were examined carefully for the presence of ticks and in positive cases ticks were collected manually and identified on the basis of morphological characters. A total of 713 cattle were examined and out of which 452 (63.39%) cattle were found to be infested with hard ticks and the prevalent tick species was Rhipicephalus (Boophilus) microplus. A significantly (p < 0.01) higher infestation was observed in female cattle (66.43%) than males (48.83%). Age-wise highest prevalence of tick infestations was found in 1–5 years (73.41%) age group followed by >5 years age group (61.92%) and < 1 year (42.65%) age group, respectively. Seasonally, the prevalence of hard tick infestation was found highest (p < 0.01) in monsoon (77.91%) and lowest in winter (43.16%). The present study provides data on tick infestation in cattle of Mizoram, India.     

The impact of Ixodiphagus hookeri, a tick parasitoid, on Ambl yomma variegatum (Acari: Ixodidae) in a field trial in Kenya

In an experiment to investigate the effect of the tick parasitoid, Ixodiphagus hookeri, on tick numbers on cattle, 150 000 parasitoids were released over a period of 1 year in a field where ten cattle infested with multiple tick species were kept. Amblyomma variegatum was reduced from 44 to two ticks per animal while Rhipicephalus appendiculatus increased over the time of parasitoid release. During the time of release 51% of the nymphs of A. variegatum collected from the animals were parasitized. The recovery of the parasitoids after the releases were stopped was only 9%. The total numbers of A. variegatum remained low up to 1 year after the parasitoid release was stopped. This study gives an insight into how I. hookeri could be used strategically for the management of A. variegatum on small-scale farms.     

Studies on the economics of ticks in Zambia

Two herds of experimental Sanga cattle were maintained under traditional savanna grazing management for three years in the Central Province of Zambia. One herd was kept free of ticks by regular acaricide treatment, while the other was given no tick control. Milk production, growth rate, fertility and mortality were monitored throughout the trial. The tick-free herd performed significantly better than the tick-infested herd, but the value of the additional production was much less than the cost of the acaricide used. it is concluded that there is no economic justification for intensive tick control under these conditions. However, strategic tick control would be justified if the quantity of acaricide used could be reduced by 50% without any major reduction in benefits. The results indicate that treating calves below 45 days of age reduces their performance, as does treating cows during periods of very low tick challenge. Therefore, it seems likely that economically beneficial strategic tick control policies could be developed.     

Boophilus microplus: rejection of larvae from British breed cattle

Larvae of Boophilus microplus were labelled with [32P] and used to study the rejection of larvae from British breed cattle with different levels of resistance. On animals of high resistance the loss of larvae due to grooming ranged from 9-54% during the first 24 h of infestation, and more time was spent grooming by these animals. Most of the grooming activity could be attributed to the presence of tick larvae and the presence of older tick stages did not increase the percentage of larvae lost. Grooming was directed to attached larvae and these could be removed. Animals of low resistance did not lose a significant number of larvae as a result of grooming, but all previously infested hosts lost a proportion of the larvae (18-39%) which could not be accounted for by grooming. This loss was greater than the total loss of larvae (11%) on animals not previously exposed to B. microplus.     

Clinico-biochemical use of serum acetylcholine esterase following treatment with synthetic pyrethroids, cypermethrin and fenvalerate, in cattle and buffalo experimentally infested with Boophilus microplus

Following treatment, cypermethrin and fenvalerate, were found to have inhibitory effect on serum acetylcholine esterase (AchE) activity of cattle and buffalo experimentally infested with B. microplus. The pattern of AchE activity in infested-pyrethroid-treated group was found to be significantly different from either healthy or tick-infested control. There was transient increase in the enzyme activity initially, followed by gradual decline and subsequent increase leading to normal level within 7 days of pyrethroid treatment. The enzyme activity was found to be low in buffalo than in cattle and the values remained below normal level up to day 7 in tick-infested group. The reversion of AchE activity to normal level in pyrethroid-treated group indicated that these compounds are prompt and safe ixodicides with least residual effect. The present investigation concludes that estimation of serum AchE might help in the clinico-biochemical diagnosis of tick toxin and pyrethroid toxicity in cattle and buffalo treated with these pyrethroids against tick infestation.     

Prevalence of ixodid ticks on cattle in Mazandaran province, Iran

A survey was carried out to investigate the prevalence of hard tick species (Acari: Ixodidae) on cattle in Mazandaran province, Iran. A total of 953 ticks were collected from 86 infested cattle during activating seasons of ticks during 2004-2005. Nine species were identified: Boophilus annulatus (51.3%), Rhipicephalus bursa (16.8%), Haemaphysalis punctata (6.3%), Ixodes ricinus (6.8%), Hyalomma marginatum (12.5%), Hyalomma anatolicum excavatum (5.2%), Hyalomma asiaticum (0.6%), Hyalomma detritum (0.2 %), and Dermacentor spp. (0.1%). The results show that Boophilus annulatus, Rhipicephalus bursa, and Hyalomma species are dominant tick species in the surveyed area.     

The history of the cattle tick Boophilus microptus in Australia and achievements in its control

For more than 100 years, tick fever and the cattle tick have caused tremendous financial loss to cattle producers around the world. Since Australia became infected with the disease and infested with its tick vector in the mid-19th century, a great deal of research effort has been directed towards their effective control by Australian farmers, administrators and scientists. Such research has yielded information which has facilitated the development of various control strategies that have equal application in other countries afficted with the same problem. It has been demonstrated that integration of a variety of these strategies is necessary for long-lasting control.     

Resistance in cattle againstRhipicephalus appendiculatus with an assessment of cross-resistance toR. pulchellus (Acari: Ixodidae)

A comparison of the yield of engorged nymphs ofRhipicephalus appendiculatus andR. pulchellus was carried out between cattle highly resistant toR. appendiculatus but susceptible toR. pulchellus, and cattle and rabbits susceptible to both species.Resistant cattle yielded fewer and smallerR. appendiculatus nymphs than either susceptible cattle or rabbits. More nymphs of both tick species dropped from susceptible cattle but no differences were detected in the mean weight of engorgedR. pulchellus nymphs fed onR. appendiculatus-resistant and susceptible cattle, although resistant animals yielded more nymphs ofR. pulchellus than ofR. appendiculatus.An acute inflammatory reaction, accompanied by intense pruritus and grooming, was observed in the ears of the resistant cattle infested withR. appendiculatus, but no reaction was detected in the opposite ears whereR. pulchellus was feeding.The low cross-resistance between these two closely related tick species suggests that different antigens may be involved in the development of resistance in cattle to different tick species.     

Stability and tick transmission phenotype of gfp-transformed Anaplasma marginale through a complete in vivo infection cycle

We tested the stability and tick transmission phenotype of transformed Anaplasma marginale through a complete in vivo infection cycle. Similar to the wild type, the gfp-transformed A. marginale strain established infection in cattle, a natural reservoir host, and persisted in immune competent animals. The tick infection rates for the transformed A. marginale and the wild type were the same. However, there were significantly lower levels of the transformed A. marginale than of the wild type in the tick. Despite the lower levels of replication, ticks transmitted the transformant. Transformants can serve as valuable tools to dissect the molecular requirements of tick colonization and pathogen transmission.     

Immunity against Boophilus annulatus induced by the Bm86 (Tick-GARD) vaccine

Friesian cattle were immunized with two inoculations of anti-tick Bm86 (Tick-GARD) vaccine and were challenged 30 or 90 d later with Boophilus annulatus larvae derived from 1.2 g of eggs. No nymphs or adult ticks were found on the immunized cattle during four weeks after challenge. Repeated infestations (2 to 4) with larvae on three other calves during a period of 160 and 390 d after the immunization did not result in development of nymphal and adult stages. In control, non-immunized cattle infested with corresponding batches of larvae 1380 to 4653 replete adult female ticks were collected. Larvae issued from Babesia bovis-infected female ticks transmitted the infection to Bm86-immunized cattle, but the progeny of B. bigemina-infected females did not. Since B. bigemina is transmitted exclusively by nymphal stages of Bo. annulatus these results support the observation that immunity induced by Bm86 affects the larval stage of this tick.     

Abundance of Ticks (Acari: Ixodidae) Infesting the Western Fence Lizard, Sceloporus Occidentalis, in Relation to Environmental Factors

We examined the impact of environmental characteristics, such as habitat type, topographic exposure and presence of leaf litter, on the abundance of Ixodes pacificus ticks infesting the western fence lizard (Sceloporus occidentalis) at the University of California Hopland Research and Extension Center (HREC), Mendocino County, California. A total of 383 adult lizards were slip-noosed and examined for tick infestation in April and May 1998. At least 94% of the lizards were infested by ticks and at least 20% of the females and 33% of the males carried > 15 ticks. This intensive utilization of western fence lizards (which do not serve as natural reservoirs for Lyme disease spirochetes) by subadult ticks, is probably the primary reason for the low prevalence of infection with Borrelia burgdorferi in I. pacificus nymphs and adults previously recorded at the HREC. Tick loads were higher on male than female lizards. Also, male lizards were generally more heavily infested in late April than in late May. The prevalence of tick infestation exceeded 88% in all habitat types but males collected in woodland and grass/woodland edges had higher tick loads than those collected in open grassland. Male lizards captured in open, exposed grassland tended to carry heavier tick loads in northern/eastern, as compared to southern/western, exposures, and when leaf litter was present.     

Modelling the transmission dynamics of Theileria annulata: model structure and validation for the Turkish context

A mathematical model that describes the transmission dynamics of Theileria annulata is proposed that consists of 2 host components: the Hyalomma tick population and a compartmental model of T. annulata infection in the cattle population. The model was parameterized using data describing tick infestation and the infection status of cattle in Turkey from 2006 to 2008. The tick attachment rates are highly seasonal and because of the temporal separation of infectious and susceptible ticks virtually all ticks are infected by carrier cattle, so that annual peaks of disease in cattle do not impact on infection in the Hyalomma tick population. The impact of intervention measures that target the tick population both on the host and in the environment and their impact on the transmission of T. annulata were investigated. Interventions that have a limited 'one-off' impact and interventions that have a more permanent impact were both considered. The results from the model show the importance of targeting ticks during the period when they have left their first host as nymphs but have yet to feed on their second host.     

Distribution and seasonal activity of tick species on cattle in the West Aegean region of Turkey

The aim of the present study was to determine the identity, seasonal activity and distribution of tick species of cattle in the West Aegean region of Turkey between June 2006 and May 2008. Nine villages within three provinces, viz. Manisa, Izmir and Aydin, were included in the study and a total of 75 animal barns were visited monthly for a period of 24 months and 443 cattle were examined for the presence of ticks. It was determined that 23% of cattle were infested with ticks. A total of 19,679 adult ticks were collected. The most abundant tick species was Hyalomma marginatum (33.5%) and H. excavatum (16.9%) in the study area. Seasonal appearance of the adult ticks varied among species. Adult ticks of the Hyalomma genus were present throughout the year, although in smaller numbers during the winter. Species of Rhipicephalus were detected in all seasons except autumn. Rhipicephalus (Boophilus) annulatus was identified in July and August, Haemaphysalis parva was detected during the autumn. Ixodes ricinus and Dermacentor marginatus were identified during spring, autumn and winter. The study demonstrated the presence of I. ricinus, D. marginatus, Hyalomma rufipes and Hae. parva for the first time in the West Aegean region of Turkey.     

Estimating the impact of Trypanosoma evansi infection (surra) on buffalo population dynamics in southern Philippines using data from cross-sectional surveys

Despite the widespread problem with surra (Trypanosoma evansi) in livestock, there are no published studies on its impact on host populations, probably because of the large financial and time cost involved in performing longitudinal studies. During 2002-6, a cross-sectional survey for T. evansi infection involving 1732 buffaloes from 71 villages in southern Philippines was carried out. Other livestock animals (horses, cattle and goats) in every surveyed village were also tested for infection with T. evansi but domestic buffaloes were the primary survey target. Seroprevalence ranged from 6% to 21% and 13% to 100% for buffaloes in low and high risk areas, respectively. Key demographic parameters were estimated from the age structured distributions of the sampled buffalo population for each sex. All areas were dominated by females (69%) and the annual calving rate for areas of 100% and low seroprevalence was 15% and 47%, respectively. Males were removed at a relatively high annual rate of 27% in all areas. In the main reproductive years (4-10) female removal/mortality was <1% and 10% for low and high risk areas, respectively. Older females were removed/died at a rate similar to males regardless of area. In high risk areas there were consistently more 2-year than 1-year old females and the reverse was true for the low risk areas. This implies that females were imported to the high risk areas for breeding. By assuming a stable age structure and similar size populations in each area, it was estimated that 28% of female calves need to be moved from low to high risk areas to maintain the observed age structure. In high risk areas, surra imposes significant financial losses due to reduced fertility, high mortality/removal rate and the necessity to import replacement buffaloes.