PhD

An investigation was conducted for a period of 5 years from
1974 to 1979 in to the incidence of ticks on domestic animals in Kerala,
the biology of the most common species, and their susceptibility to four
commonly available organo phosphorus compounds..
Nine different species of ticks belonging to 5 genera were
collected from cattle, buffaloes, goats and dogs in different localities of
the eleven districts of Kerala. The species of ticks
identified were
boophilus annulatus, rhipicephalus sanguineus, R.haemaphusaloides,
R.turanicus, haemaphysalis bispinosa, H. turturis, H.spinigera,
Hyalomma anatolicum and Amblyomma integrum. The commonest
among them was boophilus annulatus, which was found mainly on
cattle. The incidence of this tick was very high in the hilly areas and in
the western ghat regions. The other common ticks found on cattle were
Rhipicephalus haemaphysaloides and Haemaphysalis bispinosa. Tick
infestation was found to be rare in buffaloes and goats and the common
species found on them were Haemaphysalis bispinosa and B. annulatus.
IN dogs the species recorded in the present study were Rhipicephalus
sanguienus and R. turanicus. Variations in incidence was evidenced
from the present study. The maximum incidence was found in the
months of July, August, September, October and November.
The life-cycle of B.annulatus was completed experimentally in a
period 44 days. The maximum number of eggs produced by one tick
was 1420 and minimum 680. The incubation period was dependent on
the room temperature and variation in humidity had little influence.
The larvae were found to prefer hairy areas of the body for attachment,
and they did not attach at the hairless and exposed areas. The engorged
females were found to drop off quickly when green grass was spread on
the floor of the experimental animal’s shed.
The life-cycle patter could be summarised as:
Pre-oviposition : 1 to 6 days
Oviposition : 5 to 9 days
Incubation period : 16 to 30 days
Larval fasting : 2 to 5 days
Larval feeding : 4 to 7 days
Larval moulting : 8th to 12th day of infection
Nymphal feeding : 3 to 6 days
Moulting of Nymph : 15 to 19th day of infection
Adult feeding : 5 to 10 days
Detatchment of female : From 20th day of infection
onwards
Four
organophosphorous
compounds
viz.
Malathion,
Fenitrothion, Dichlorvos and Phosalone were tested for their action on
ticks. The ovicidal and larvicidal actions and the lethal effects on
nymphas and engorged females of B. annulatus, R sanguinius and H.
bispinosa were studied in the laboratory. Cythion (malathion 50%) 0.5
to 1%, Sumithion (Fenitrothion 50 %) 0.5 to 1%, Dichlorvos (Nuvan)
0.1 to 0.2%, and Zolone (Phosalone 35 %) 0.2 to 0.3% were found
effective at different degrees. The efficacy was directly proportional to
the concentration of compound and the duration of treatment.
Phosalone showed maximum efficacy followed by Dichlorvos.
In field trials, all the four compounds gave satisfactory results.
But phosalone showed maximum efficacy and least toxicity to animals.
Nuvan was also effective but was the most toxic among the four
compounds. Thus the acaricide of choice for routine use in Kerala was
determined to be Phosalone (35%) at a concentration of 0.3% to be
used as a spray or wash.