Cattle ticks

Famphur was not very effective in the control of ticks. The tropical horse tick (Anocentor nitens) is a species of serious concern to horse breeders and raisers in Florida mainly because it transmits Babesia caballi, the causative agent of equine piroplasmosis. A secondary concern is that heavy tick infestations may cause injury to the ears of the horse (Gladney etal. 1972). Data were unavailable on famphur control of ticks in horses however, famphur was 99.9 to 100% effective in controlling A. nitens in Hereford steers and heifers when fed in the diet at 5 mg/kg BW for 14 to 21 days. Famphur at 2.5 mg/kg BW in cattle diets for 7 days was only partially effective (39 to 87.5%) in controlling horse ticks (Gladney et al. 1972). Famphur — despite multiple treatments — was not effective in controlling cattle ticks (Haemaphysalis longicornis) when used as a pour-on at recommended application rates in weaned Hereford calves (Heath et al. 1980). 

In Central and South America the torsalo, screwworm, and cattle ticks are responsible for a large part of the injury attributable to external parasites. The bloodsucking flies, lice, and mange mites also are present and cause significant losses to growers of cattle and the wooled animals. 

Support for this is found in the substantially greater octopa-minomimetic activity of DCDM compared to chlordimeform (20) and the observation that mixed function oxidase inhibitors, e.g. piperonyl butoxide and sesamex, strongly antagonized the toxicity of chlordimeform to the southern cattle tick larvae and synergized the toxicity of DCDM (21). Therefore, chlordimeform may be considered to be a propesticide of DCDM. 

Stylosanthes hamata and scabra, which are highly productive and nutritious species of tropical pasture legumes, are covered with glandular trlchomes. The trlchomes secrete a viscous secretion that immediately Immobilize larvae of the cattle tick, Boophllus mlcroplus (39). Ticks have a natural tendency to climb plants, and wait for a host animal. The secretion has no repellant properties, so that ticks do not attempt to seek alternative plants. In addition to Immobilizing the larvae, the plants produce an unidentified volatile compound(s) that poison the larvae, within 24 hours. 

Ndumu et al. evaluated the effectiveness of Azadirachta indica seed oil against the larvae of this parasite [95]. They administered the oil as hydroalcoholic solutions ranging 4.2-100% and computed the mortality within 60 hours. Authors observed that the mortality of larvae was concentration and time dependent 100% mortality was observed with 100% pure neem oil after 48 h. The LD50 of different concentrations were 33.3% (56 h) and 66.7% (48 h). Author also observed little or no adverse effects on treated animals. Furthermore, they stated that the open wound caused by tick bites and therefore exposed to potential fungal and bacterial attacks, could be protected by the microbicidal properties of the neem oil. Previously, the effectiveness of neem oil was also observed by Williams and Mansingh against another tick species of the same genus, A. cajennense, another cattle tick [96]. 

Control of cattle ticks has followed a similar transition from broad spectrum organophosphates to more selective agents with novel mode of action. In 1956 diazinon (81) was introduced into Australia as the first organophosphate for tick control. Evidence of OP resistance was first detected in 1963 and in 1966 chlordimeform (84) was demonstrated to control the OP-resistant strains. 

The control of lice, mites and warbleflies continues to be achieved by the older agents. The selection pressure that caused resistance in cattle ticks and sheep blowfly has not been encountered by these other ectoparasites since their less frequent incidence has required less insecticide/acaricide usage. In addition to the OPs, rotenone (92) (the active principle of derris), an uncoupler of oxidative phosphorylation, continues to be used to combat mange. 

Chen A, Holmes SP, Pietrantonio PV. Molecular cloning and functional expression of a serotonin receptor from the Southern cattle tick Boophilus microplus (Acari Ixodidae). Insect Mol Biol 2004 13 45-54. 

Starting in 1908 in the orchards of the Pacific northwest, the cases of resistance before World War II and the era of the synthetic organics involved the HCN used against scale insects on citrus, the arsenicals used against orchard caterpillars and cattle ticks, and tartar emetic applied against the tiny insect pests called thrips as now, many instances originated in California (Table I). The resistance mechanisms were investigated in two of... 

Successive resistances have driven control of the Boophilus cattle ticks all the way to OP compounds, and from them to chlor-phenamidine (chlordimeform) although it has been recently found that carbaryl is effective in cattle dips if synergized with piperonyl butoxide. The two-spotted mite has gone through a fantastic sequence of acaricides, the only ones to which resistance has not yet been reported being Pentac and the organo-tin compound Plictran. 

Gene Housefly Tobacco Budworm Culex fatigans 2-Spotted Mite Predaceous Mite Cattle Tick... 

Chen, A.C., He, H., and Davey, R.B., Mutations in a putative octopamine receptor gene in amitraz-resistant cattle ticks, Vet. Parasitol., 148, 379, 2007. 

More recently, Chen et al. (2007) found two amino acid substitutions (T8P, L22S) in a putative octopamine receptor in amitraz-resistant cattle ticks. Thus, point mutations may play a role in resistance to formamidine pesticides in ticks. 

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