Host resistance to cattle tick (Boophilus microplus) in Brahman (Bos indicus) cattle. IV.* Ages of ticks rejected

1979 ◽  
Vol 30 (1) ◽  
pp. 211 ◽  
Author(s):  
BM Wagland

The stages of development of Boophilus microplus against which Brahman (Bos indicus) cattle manifest resistance were investigated by analysing the age distributions of ticks in populations on five steers showing different levels of resistance. The populations of ticks were established by infesting the steers each day with 1000 larvae, until each animal yielded a relatively stable number of engorged female ticks daily. The ticks were recovered by killing the steers and processing their hides in hot caustic soda. Ticks were allocated to age categories on the basis of their lengths. Analyses of the age distributions showed that between 36 and 80% of larvae were rejected in the first 24 h, and losses were greater from hosts with high levels of resistance. Some newly moulted nymphs failed to establish and were lost, and the growth of newly moulted females was retarded but most engorged successfully. The results also indicated that significant numbers of larvae and nymphs were lost either during the final stage of engorgement or after they had engorged. These findings are compared with losses of the tick from European (B. taurus) cattle. __________________ * Part III, Aust. J. Agric. Res., 29: 401 (1978).

1975 ◽  
Vol 26 (6) ◽  
pp. 1073 ◽  
Author(s):  
BM Wagland

Four purebred Brahman and four beef Shorthorn cattle which had not previously been exposed to Boophilus microplus were infested four times with 20,000 B. microplus larvae. On first infestation, the yield of engorged female ticks on all animals was about 25% of the larvae applied. Aftcr three further infestations, the mean yield of engorged females on the Brahmans decreased to 7.5% whereas there was no decrease in the yield of ticks on the Shorthorns. On the Brahman cattle. development of larvae to engorged females took 1–2 days longer and the engorged females weighed less. However, there was no difference in the reproductive index of female ticks engorged on either Brahmans or Shorthorns. Increases in rectal temperatures occurred in all cattle 15–17 days after the first infestation and in some cattle on days 6–7 as well as on days 15–17 after reinfestation. It was concluded that resistance to B. microplus is an acquired phenomenon in Brahman cattle.


1978 ◽  
Vol 29 (2) ◽  
pp. 395 ◽  
Author(s):  
BM Wagland

The dynamics of host resistance to Boophilus microplus was investigated in previously unexposed and exposed Brahmans, and in previously unexposed Shorthorn cattle. The animals were infested each day with 1000 larvae, and the development of resistance was monitored by counting the number of female ticks which engorged. The previously unexposed cattle showed an initial period of susceptibility (phase I) which was followed by a period in which most animals developed degrees of resistance (phase II), and which stabilized in some animals (phase III). The duration of phase I was shorter in Brahmans, and they developed higher levels of resistance (phase III). In contrast, previously cxposed Brahmans manifested phase III levels of resistance immediately on infestation. The results provide further evidence that resistance to B. microplus in Brahmans, as well as in European breeds, is acquired rather than innate. __________________ *Part I, Aust. J. Agric. Res., 26: 1073 (1975).


1978 ◽  
Vol 29 (2) ◽  
pp. 401 ◽  
Author(s):  
BM Wagland

Length measurements were used to compare the growth of the parasitic stages of Boophilus microplus on previously unexposed Brahman (Bos indicus) and Shorthorn (B. taurus) cattle. Growth curves based on the length measurements were constructed. Growth was slower on Brahmans than on Shorthorns during the first 24 hr of larval and nymphal instars. After the first 24 hr, the growth rates of larvae, and of nymphs, during feeding to engorgement were the same on the rump and belly regions of both species of cattle. Larvae and nymphs engorged more slowly on the brisket than they did on the rump and belly regions of the Brahmans. The surface skin temperature was lower on the brisket of the Brahmans. On the basis of change in the length of the tick during development on Brahmans, 16 age categories were established, so that the length of the tick may be used to estimate the ages of ticks in populations on Brahman cattle. Age categories were also defined for ticks which had been processed in formalin and hot alkali. __________________ *Part II, Aust. J. Agric. Res., 29: 395 (1978).


1988 ◽  
Vol 39 (2) ◽  
pp. 285 ◽  
Author(s):  
RW Sutherst ◽  
ID Sutherland ◽  
AS Bourne ◽  
GF Maywald ◽  
DA Stegeman

An experiment is described which compared the fluctuations in the numbers of cattle tick, Boophilus miicroplus, that resulted from direct climatic effects or from changes in host resistance. Four herds of cattle, matched for tick resistance and with different Bos indicus (zebu) content, were grazed at each of two locations, one in central Queensland (23� S.) and one in southern Queensland (28� S.), from November 1977 to May 1982. Natural tick populations were counted regularly, and host resistance was measured using artificial infestations, either twice or six times a year. Concurrent exposures of engorged ticks in pastures were used to measure the success of the ticks in producing larvae and to partition mortality during development. Two later papers report other aspccts of the experiment. These include observations on the resistance of cattle to ticks and on the relationship between tick numbers on the cattle on one hand, and the availability of larvae on pasture and survival of parasitic stages on the other. Engorged ticks produced more larvae throughout the year in central Queensland, despite laying fewer eggs. The colder and longer winter in southern Queensland greatly reduced tick reproduction. Failure of engorged ticks to survive predation and find a favourable oviposition site, egg mortality and loss of larvae in the pasture accounted for most of the reduction in the potential number of larvae produced. Reduced oviposition was also important in wintcr.


Parasitology ◽  
1971 ◽  
Vol 63 (2) ◽  
pp. 323-330 ◽  
Author(s):  
D. H. Kemp ◽  
D. Koudstall ◽  
J. D. Kerr

SUMMARYAfter 24 h desiccation at 28–29 °C and approximately 50 % relative humidity about 70 % of B. microplus larvae drank sufficient solution containing 1·5 mCi of 32P per ml for their movements on the host to be followed with a portable G-M counter. Reduced viability of the labelled ticks could not be detected when they were kept for 24 h on the host and either allowed to feed or prevented from doing so. When feeding was continued for 72 h or when larvae were incubated for 3–4 weeks, adverse effects were found, the severity of which could not be directly related to the amount of 32P label. Desiccation, handling of larvae and exposure to radiation in the drinking solution may have contributed to their reduced viability.Since resistance to the tick is manifest within the first 24 h after infestation labelled larvae could be used to compare development on different hosts during this time. Even after feeding for 72 h, larvae were more adversely affected by host resistance than by labelling damage.We would like to thank Mr C. A. Schuntner for helpful advice and Mrs J.Galligan for technical assistance. The financial support of the Australian Meat Research Committee is gratefully acknowledged. Messrs D. Hancox and S. R.Henderson assisted with some of the experiments.


2008 ◽  
Vol 126 (1-2) ◽  
pp. 110-119 ◽  
Author(s):  
Emily K. Piper ◽  
Louise A. Jackson ◽  
Neil H. Bagnall ◽  
Kritaya K. Kongsuwan ◽  
Ala E. Lew ◽  
...  

Parasitology ◽  
1980 ◽  
Vol 80 (3) ◽  
pp. 487-496 ◽  
Author(s):  
D. H. Kemp ◽  
A. Bourne

SummaryCircumstantial evidence suggests that the earlier detachment of Boophilus microplus larvae from highly resistant cattle follows the release of histamine at the attachment site. In vivo and in vitro experiments show that a proportion of the larvae will detach following injection or infusion of histamine. Other mediators such as bradykinin, prostaglandin E2, 5-hydroxytryptamine and dopamine have little or no effect on tick behaviour in vivo. Sensitivity to histamine declines as larval attachments stabilize, and repeated injections have no effect on the weight of larvae after 3 days on the host. Response to histamine is discussed in relation to host resistance, histology of the feeding lesion and larval behaviour.


1988 ◽  
Vol 28 (1) ◽  
pp. 1 ◽  
Author(s):  
RG Holroyd ◽  
PJ Dunster ◽  
PK O'Rourke

The effects of cattle tick infestations on liveweight and fertility of Droughtmaster (1/2 Bos indicus) cows and on calf weaning weights were determined over 3 years. Tick populations on the control (non-dipped) group of cattle fluctuated, with mean annual tick counts/side being 9.5, 8.9 and 13.6 for years 1, 2 and 3 respectively, while the treated group of cattle, which were dipped every 21 days, were free of ticks. Tick counts were not related to fertility or liveweight change in pregnant-lactating cows or to calf growtb or weaning weights. Treatment for ticks significantly (P<0.05) affected liveweight change in pregnant-lactating cows on only a few occasions, and annual liveweight changes were not significantly influenced by treatment. When lactating cow pregnancy rates were low (< 30% for control cows), treatment for ticks increased the pregnancy rate by about 100% in 2 of the 3 years, these differences being significant only in the last year. Calves in the treated group were born significantly earlier in the first year and had significantly lighter birth weights in the third year. Treated calves grew faster to weaning and had higher weaning weights (mean difference 17.9 kg) than control calves but differences were significant in the first and third years only.


1983 ◽  
Vol 34 (3) ◽  
pp. 329 ◽  
Author(s):  
RW Sutherst ◽  
JD Kerr ◽  
GF Maywald ◽  
DA Stegeman

The host resistance of Bos tauvus (British) and B. indicus x B. tauvus (Zebu x British) steers and heifers to cattle tick (Boophilus microplus) was measured at about monthly intervals for periods of up to 2: years in south-eastern Queensland. The cattle either grazed native pasture, with or without a supplement of lucerne pellets, or were fed entirely on lucerne pellets in yards. Animals grazing native pastures, with poor quality feed in late-autumn and winter, suffered substantial losses of resistance. Up to five times as many ticks survived on them in autumn-winter as in spring-summer, regardless of breed. A less-marked cycle of resistance was observed on all animals fed on lucerne or lucerne supplement, with 2-3 times as many ticks reaching maturity from a constant infestation of larvae in autumn-winter as in spring-summer. Zebu x British steers yielded the same numbers of ticks as heifers in winter but twice as many as heifers in summer. No difference was observed in the yield of ticks from the heifers and steers of British breed at any time. A hypothesis is proposed that the primary cause of the seasonal loss of resistance is the hosts' physiological response to shortening photoperiod. Recovery of resistance is spontaneous once some adaptation to winter conditions has been completed, usually around the time of the winter solstice. Nutritional stress accentuates the loss of resistance and delays its recovery.


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