Farm animals are attacked by a number of ectoparasites from among insects, ticks and mites. The insect pests generally breed on carrion, wounds of diseased animals and sometimes even on healthy animals. They are good fliers and attack the host for sucking their blood. In this process, they cause a great annoyance to cattle, buffaloes, horses and other domestic animals.
The ticks and mites are wingless and live, more or less, a sedentary life. In their case, infestation from one animal to another is through contact or when an animal touches the objects on which the parasite might be awaiting its arrival. Some of the parasites are also known to transmit diseases.
1. Sucking Cattle Louse, Haematopinus Surysternus Denny (Phthiraptera: Haematopinidae):
It is a universal parasite of cattle. The adult is wingless and slate grey. It is about 3 mm long, has a flat body and pointed legs. The nymph is similar in shape. In addition, many other species of blood-sucking lice infest domestic animals in India, Pakistan and adjoining countries.
Other important species include H. quadripertusus Fahrenhoiz, the tail switch louse of cattle, which attacks mainly the tail switch, but may also be seen among the long hairs, around the anus, vulva and eyes; H. tuberculatus (Burmeister) is louse of wild and domestic pigs but it also occurs on goats; Linognathus vituli (Linnaeus) is the calf louse and is more often seen around the horns and on the neck; goat is also infested with Haematopinus sp. and Linognathus stenpsis as well as L. africanus.
Life-Cycle:
Lice are active throughout the year but breed more actively during summer. A female deposits 25-30 peg-shaped yellow eggs(nits), which are glued fast to the hairs at the base. They hatch in 15-18 days. The nymphs feed frequently, moult three times and are mature in two weeks, when they start laying eggs. They move about very little except when laying eggs. The life- cycle is completed in three weeks and several generations are completed in a year.
Damage:
The lice cling to the hairs with their claw-like legs and thrust their mouthparts into the skin for sucking blood. These lice suck blood of the host and while doing so they inject saliva which has toxic properties. Louse bite produces irritation and causes itching as a result of which the animal attacked rubs itself vigorously against any available rough surface.
Patches of skin become devoid of hairs and sores might develop there. Haematophagus flies which get attracted to these wounds are a further source of annoyance to the animal. The animal becomes restless, loses appetite and does not gain weight. The loss of blood weakens the young host, with the result that the normal production of milk and meat is adversely affected.
Control:
(i) Malathion or carbaryl 5 per cent dust or 0.5 per cent suspension as a dip are effective.
(ii) The application of raw linseed oil all over the surface of the body is also effective in killing the sucking lice.
2. Chewing Lice:
They mostly infest poultry but a few species are parasitic on sheep, goats and buffalo calves. The more common species of chewing lice that infest fowl in India are- Menacanthus stramineus (Nitzsch) (Phthiraptera: Menoponidae) (chicken body louse) occurring mostly on the skin; Menopon gallinae (Linnaeus) (shaft louse) present on shaft of feathers; Cullutogaster hetrographus (chicken head louse) occurring on the skin and among feathers of head and neck; Goniocotes gallinae (DeGeer) (Goniodidae) (fluff louse) occurring on Huffy basal parts of feathers; G. dissimilis (brown louse) occurring on wing covers and large feathers of body; Goniodes gigas Taschenberg (large hen louse) occurring mostly on feathers; Lipeurus caponis (Philopteridae) (wing louse) occurring on large wing feathers and L. tropicalus (tropical hen louse) occurring generally on the base of head and neck feathers. The chewing lice that infest sheep, goat and buffalo calves are Damalinia ovis (Schrank), D. caprae (Gurlt) and D. bovis (Linnaeus) (Trichodectidae), respectively. Among the poultry lice, the shaft louse, Menopon gallinae (Linnaeus), is a universal parasite of domestic fowl.
Poultry Shaft Louse, Menopon Gallinae (Linnaeus) (Phthiraptera: Menoponidae):
It is called the ‘shaft louse’ of fowl because it is seen running towards the body along the shaft of a feather when the bird parts its wings. Its body is dorso-ventrally flattened and wingless. It is about 1.5 mm in length and has biting mouth parts. The louse is more abundant on poultry than on other species.
Life-Cycle:
M. gallinae moves about quickly in the feathers. The female deposits eggs singly on the down or on the feathers. The eggs hatch in 4-7 days. The nymphs feed on the epidermal scales and moult three times. They are mature in 4 weeks. The life-cycle is completed in 4-5 weeks and a number of generations are completed in a year, the eggs being more abundant from November to February.
Damage:
These lice feed on feathers, downs and epidermal scales resulting in itching and falling of feathers. Heavily infested birds lose healthy condition, become weak and egg production is lowered. The young birds suffer from retarded growth and development.
Control:
(i) The chickens may be sprayed individually or in groups with water-based sprays of 0.5 per cent carbaryl or malathion @ 5 litres per 100 birds,
(ii) The dusts of 5 per cent malathion or carbaryl may be thoroughly applied preferably to the individual birds 500 g per 100 birds.
3. Biting Gnats:
They include sand-flies, biting midges and black-flies.
(a) Sand Flies:
Sand-flies of the Phlebotomus spp. are vicious biters and suck blood mostly of cattle and buffalo but they also bite human beings. Thirty species of this genus have been reported from India but P. argentipes Annadale & Brunetti, P. papatasi (Scopoli), P babu and P. minutus (Rondani) (Diptera: Psychodidae), are more important.
These are minute; greyish brown flies about 1.5-3.5 mm in length. They are widely distributed in India. Their bodies and wings are thickly covered with hairs but are devoid of scales. The larva is hairy and carries 2 pairs of long bristles at the last abdominal segment.
Life-Cycle:
Sand-flies are active at night and remain hiding in the day time. They breed in any damp, moist place, containing organic matter but away from light. The biting activity of the flies increases in those nights when the temperature is high and there is little or no breeze.
The eggs laid in organic matter hatch in about 3-7 days. The larval and pupal stages together last about 30 days. The larvae feed on solids and they moult four times. The pupa always carries the last larval skin around two distal segments of the abdomen, which is bent upwards. The adult flies live for 40 days.
Damage:
Sand-flies are vicious biters and suck blood mostly of cattle and buffalo. In addition to debilitating the animals by sucking their blood they transmit canine leishmaniosis. All of them also transmit kala-azar, oriental sore and sand-fly fever in human beings.
Control:
(i) The population of sand-flies may be reduced by keeping the dark corners in and around sheds dry and clean of organic matter.
(ii) The flies are attracted to light at night and, thus, may be killed on the wall around lamps.
(iii) Dust the dark corners in and around sheds with malathion 5 per cent dust.
(iv) Spray the sheds to the point of run-off, using water based sprays @ 5-10 litres per 100 m3 containing 0.5 per cent diazinon or 1 per cent malathion or 1 per cent ronnel.
(b) Biting Midges:
Biting midges of the genus Culicoides are persistent and irritating pests of animals and human beings. About 30 species of Culicoides have been reported from India which is more common in Assam and Bengal.
These midges are dark brown and 1.0-1.5 mm long. The wings are usually hairy and are marked with spots and circles.
Life-Cycle:
The body of larva is slender, has a few hairs and bears 4 pairs of appendages at the last segment. Culicoides breed in water or semi-aquatic situations, containing manure or urine of cattle or washings from the stables. Minute eggs are deposited in several batches. The egg stage is completed in 3-4 days. The larvae feed for 7-70 days and then enter into pupal stage for 3-7 days.
Damage:
The females suck blood and by their bites cause severe irritation. Some species of Culicoides are intermediate hosts of the helminth parasite, Onchocem gibsoni, which causes worm nodules in cattle.
Management:
(i) The breeding of biting-midges can be reduced by not allowing the water flowing out of sheds to stagnate.
(ii) Spray 2 per cent oil emulsion of malathion at the places where these insects are breeding.
(c) Black-Flies:
Of the 100 species of black-flies reported so far, about 32 of the genus Simulium occur in India. These flies are small, robust and dark in colour and measure 3-6 mm in length. Females are vicious biters and suck blood mainly of cattle and horses.
Life-Cycle:
These gnats breed mainly in running water. Eggs are laid in masses on submerged objects such as aquatic plants, rocks and sticks. A female gnat lays about 500 eggs which are enveloped in a gelatinous substance. Eggs hatch after 7 days. The larvae feed on algae and animalcules for 4-5 weeks and undergo pupation inside cocoons. The pupal stage lasts 5-14 days. The adults escape through a slit in the cocoon and are carried to the surface of the water on a bubble of air collected during the transformation period.
Damage:
Black-flies are vicious biters. Their bites cause severe irritation and May also cause swelling which is due to the toxic properties of their saliva.
4. Gad Flies, Tabanus Spp. (Diptera: Tabanidae):
There are more than 2,000 species of blood sucking gad flies or horse flies in the family Tabanidae, of which about 150 occur in India. The female fly bites and sucks blood from its shoots, which include horse, cattle, camel, elephant and sometimes man. The male feeds on nectar, honeydew, oozing tree-sap, etc. The fly is characterized by a thick-set body, a large head and big eyes.
Different species have their feeding preference for certain sites on their hosts. For instance, Tabanus rubidus Wiedemann (Diptera: Tabanidae) settles on the lower parts of the back of the hind legs; T. striatus Fabricius on the undersurface of the abdomen; T. macer Bigot on the sides of the neck; T. ditaeniatus Macquart on the udder; Chrysops dispar Fabricius on the inner side of the fore legs and Haematopota javana Wiedemann on the hump or the neck.
Life-Cycle:
The tabanid flies are abundant in those areas where temperatures are moderately high, water is available and forests are close by. They are particularly common during the monsoon when they are seen sitting on walls or on window panes. They love the sunshine and are active during the day-time only.
It appears they find their hosts by sight and not by smell and they even attack animal dummies. They are also attracted by moving objects such as railway trains. Females generally attack the animals in the sun and a blood meal is essential for the maturation of eggs which are deposited in masses on aquatic and subaquatic vegetation as well as logs of wood near water.
Quite often, the egg masses are cemented together with a thin layer of transparent material which is water-proof. The eggs are torpedo-shaped, 1-2 mm long and are white when freshly laid but become darker later on. In one cluster, there may be 300-600 eggs which hatch in 4-7 days.
A larva, on emerging from the egg, is white and tapers at both end and measures about 3.5 mm. It is aquatic and feeds on small crustaceans or on the maggots of flies. The larvae of Chrysops sp. or of Hamatopota sp. may also be found in mud, moist soil or manure.
They pass through 7- 8 instars and may complete their development in 9 days to almost 7 months, depending upon the species, season and food supply. On completing their development, the larvae move to drier soil on the banks of streams to the edge of ponds or to similar aquatic habitats.
The pupa is generally yellowish brown, finely wrinkled and has a lateral tuft of hairs on each abdominal segment. The pupal stage lasts from 3 to 21 days and the flies, on emergence, have iridescent eyes. In various species, the life-cycle is completed in 4-5 months and there are usually two broods in a year.
Damage:
The female flies are parasitic on warm-blooded animals and suck blood which may ooze from the site of feeding. It is not uncommon to see as man as 50 flies on a single host. While taking blood meal, the female inserts and withdraws the beak several times, shifting to a new place every time.
Thus, she completes her meal in 3-11 minutes from 5-6 places and at the end of that period her abdomen is so fully distended that occasionally a drop of host blood comes out of its anus. Generally, there is an interval of 1-2 days between the meals. The flies are responsible for the dissemination of a number of diseases of cattle, viz., surra, anaplasmosis, anthrax and swamp fever and a kind of filariasis in human being.
Control:
(i) Stagnant water in the area should be drained away to prevent the breeding of the pest, and
(ii) The application of sprays containing 0.1 percent pyrethrins +1 percent piperonyl butoxide at 1-2 litres per animal, twice or thrice a week, is effective.
5. Bot and Warble Flies, Oestrus Ovis Linnaeus and Hypoderma Lineatum (Villers) (Diptera: Oestridae):
The bot flies in the larval stage act as parasites on the flesh of various domestic animals. They attack cattle, horse, sheep, goat, elephant, rhinoceros, etc., and feed in the alimentary tract, the nasal and pharyngeal cavities and in subcutaneous tumours formed by their bites. In India, these flies belong to the genera Oestrus, Hypoderma, Cobboldia, Rhinoestrus (Oestridae), Gyrostigma and Gasterophilus (Gasterophilidae).
The sheep or goat-bot fly, Oestrus ovis Linnaeus, is distributed throughout the Indian Sub-continent and its larva is the familiar head maggot of the two domestic animals. The larva of Rhinoestrus purpureus (Brauer) has been recorded from the nasal passages of horses in the Punjab.
Hypoderma lineatum (Villers) is the well-known warble fly on cattle, which is occasionally found on goat also. It attacks the skin and is responsible for deterioration in quality of the hide. There are instances when larvae of Hypoderma and Gasterophilus have been collected from the skin of man and are known to cause ‘creeping myiasis’.
Life-Cycle:
The parasitic forms of bot flies which live in the alimentary canal of animals deposit their eggs among the body hair, from where their larvae are swallowed through licking. The larvae of the forms that parasitize the naso-pharynx are deposited in the nostrils. Those found in the skin lay their eggs on the legs of host. On emergence from eggs, the larvae penetrate inside and after passing through various tissues reach the back of the host.
The warble fly is common in the western parts of India and causes tumours in the skin of cattle and buffaloes, thus spoiling the hide. The adult fly is 12-14 mm long and has a wing expanse of 23- 25 mm. The body is black, banded with yellowish and orange hairs. Legs are well covered with hairs of black and orange colour.
The wing veins are black. The dull-yellowish-white eggs, which have a smooth shining surface and are about three quarters of a millimetre in length, are deposited on the body hair in groups of 5-12. The total number of eggs laid by a female fly varies from 200 to 500.
The eggs hatch in 4-5 days and the young larvae penetrate the skin through hair follicles. Within 2-3 months, they reach the wall of the oesophagous and later on by way of the thoracic cavity they reach the back where characteristic warbles are produced in about 7 months. There are three larval instars.
The final instar larva cuts a small hole in the skin covering the warble for breathing air from outside. This results in damage to the hide. The mature light brown larva wriggles out of the warbles through a hole and drops on the ground to pupate in soil. After a pupal period of 6-8 days, the adult fly emerges.
It lives only for a few days for mating and reproducing. In the plains of north-west India, the egg-laying season of ox-warblefly extends from March to June. Warbles appear on the back of the cattle from October to January. There is only one generation of this fly in a year.
Damage:
The penetration of the larvae into skin causes irritation and later on hypodermal rash is produced, which may be mistaken for mange. Cows infested by warble-fly yield less milk. The flesh around the mature larva gets inflamed and becomes unfit for consumption.
Control:
(i) Hair close to the hoofs may be cut in order to destroy the eggs during the egg laying season, i.e., monsoon months.
(ii) The larvae can be easily squeezed out from the cyst and this removal decreases the suffering of the animal.
(iii) The water-based sprays containing 1 per cent trichlorphon or 0.05 per cent rotenone are applied for controlling the pest. The entire body of the animal is wetted to the skin. The first treatment is given 40-45 days after appearance of first warbles on the back. The treatment is repeated at 45-day intervals as long as the grubs on appearing on the back.
6. Camel Nasal Bot Fly, Cephalopina Titillator (Clark) (Diptera: Oestridae):
In India, the camel nasal bot-fly is present in Rajasthan. The adult fly looks somewhat like O. ovis, the nasal bot-fly of sheep. The upper part of the head is orange and lower part is pale yellow. The thorax is reddish brown. The legs are yellowish brown and the terminal parts of tarsi are dark. The adult fly measures 8-11 mm long.
Life-Cycle:
The female fly deposits its larvae in the nostrils. The larvae bore into the nasal passages and feed for 3-11 months and then fall down on the ground to pupate in soil. The pupal stage is completed in 18-25 days. The adult fly lives for 38 days.
Damage:
When the flies deposit larvae in the nostrils, the animal sneezes and snorts violently due to severe irritation. The mature larvae leave the nasopharynx and crawl down to the nostrils of the camel. The animal becomes restless, shakes its head continuously, becomes dull, stops feeding and starts sneezing and snoring. The presence of larvae in the nasal passage of the camel sets up inflammatory changes causing great discomfort. An offensive discharge tinged with blood comes out of the nostrils.
Control:
This malady can be controlled by applying inside the nostrils 0.2 per cent suspension of trichlorphon.
7. Stable Fly, Stomoxys Calcitrans (Linnaeus) (Diptera: Muscidae):
This fly and many other species of the subfamily Stomoxydinae are true blood-suckers and are commonly known as the stable-flies or biting flies. They are distinguished from other muscids by their having characteristic elongated apical portion of the proboscis. It is longer than the length of the head, swollen at the base and tapering at the apex. S. calcitrans is cosmopolitan and feeds on the blood of cattle, horse and other domestic animals.
Life-Cycle:
Both sexes suck blood from the host becoming engorged in 2-5 minutes. They feed two times a day. The fly breeds in litter mixed with dung and urine, in sewage mud or fermenting tidal deposits. A female starts egg-laying one week after emergence and may lay up to 600 eggs.
The eggs measure 1.3 mm in length and are white, when freshly laid. They hatch in 36-48 hours. The larval stage is completed in 2-3 weeks and the full-grown larva measures about 10 mm. The puparium is mahogany brown and 4.5 mm in length. The pupal stage lasts about 10 days and the life-cycle is completed in 4-5 weeks.
Damage:
The stable-flies are notorious for biting, irritating and causing restlessness in cattle. According to one estimate, these flies cause 9.26 per cent reduction in milk yield during a month’s infestation as compared to 3.33 per cent reduction caused by Musca nebulo. Stomoxys niger Macquart, a related species, is the vector of surra in Mauritius, but it is not known to be an efficient vector of this disease in India. However, it may spread anthrax.
Control:
(i) The animal can be sprayed with 0.05 per cent pyrethrins +0.5 per cent piperonyl butoxide (1-2 litres per head) once or twice a week. Alternatively, the animal may be treated with malathion 5 per cent dust @ 50 g/ dairy cattle.
(ii) The pest can be controlled by spraying 1 per cent diazinon on the surfaces in the cattle sheds.
8. Buffalo Fly, Siphona Exigua (De Meijere) (Diptera: Tachinidae):
The buffalo-fly is yellowish grey and is smaller than the stable-fly. The proboscis is very slender and projects downwards. Though normally a pest of cattle and buffaloes, it may also attack other species of livestock when the latter are moving with cattle and buffaloes. When feeding or resting on the host, the wings of this fly are held at an angle from its body.
Life-Cycle:
The buffalo-fly lays eggs only on freshly dropped dung of cattle and buffaloes. About 20 eggs are laid by a female. Eggs hatch within a day. The larvae feed for 3-5 days and pupate in the bottom layer of the dropping or in nearby soil. The adult emerges after a pupal period of 3-5 days.
Damage:
The fly is active generally during the day and feeds on the flank and neck of the cattle. The bite of this fly is painful. The fly sucks considerable amount of blood of the host. A constant attack of hundreds of flies seriously affects milk production and work efficiency of the animals.
9. Blow Flies, Calliphora Vicina Robineau-Desvoidy, Lucilia Spp. and Chrysomya Bezziana Villeneuve (Diptera: Calliphoridae):
These flies have a bright metallic appearance, being shining blue or green and are known as blue-bottles or green bottles. They are small to medium, some being smaller and other larger than the common house fly. Three of the genera of the family Calliphoridae namely Chrysomyia, Calliphora and Lucilia include the largest number of flies that feed on carrion and many of them even cause myiasis in man and domestic animals. C. vicina, Lucilia cuprina (Wiedemann), L. sericata (Meigen) and C. bezziana may be considered the type species, being also very common in various parts of India. All these species are widely distributed in various parts of the world, particularly in Eurasia.
Life-Cycle:
C. vicina is the well-known European blow-fly (blue-bottle) and is found in the Himalayas and other places in India where the climate is mild. The fly breeds in cadavers and meat. At 23°C, the eggs hatch in 24 hours and the larval and pupal stages are completed in about 10 days.
L. cuprina and L. sericata are allied species and can be crossbred. The former is the most important blow-fly on sheep in Australia and the latter in England. The colour is variable in different parts of the world. For example, L. sericata (green-bottle) is bright green in Europe and Africa, bronze-green in India and coppery in New-Zealand.
The adults of these species are commonly seen on sweets and meat in Indian bazars. A female deposits clusters of 400-500 eggs in summer. These hatch within 12 hours. The larval and pupal stages last 3-4 and 4-5 days, respectively. A full-grown larva is dirty white and is 12 mm long and the puparium is light brown. The life-cycle, including the pre-oviposition period, is completed in a fortnight. Sometimes, these flies cause muscular myiasis in animals having wounds. Excretions of L. sericata are known to contain a potent bactericide.
C. bezziana is the commonest fly that causes myiasis in India. The site of the disease may be the mouth, ears, eyes, skin or vagina of the farm animals, camels, elephants or even humans. The flies may lay eggs either right on the diseased tissue or near it, and even in the pus-soaked dressing material.
As many as 522 eggs have been recorded from one wound. The egg is cylindrical, 1.5 mm long, and hatches in 1.0-1.5 days. The mature larva is about 12 mm long white with an orange tinge, darker at either extremity. The body segments have transverse rows of short, stout, light brown, black-tipped, posteriorly directed spines.
The projections on the body give the appearance of a screw, hence the name screw worm. The larva fully matures in 5-6 days and drops to the ground where it pupates in soil. The puparium is deep mahogany. The pupal period is completed in 7-9 days. The life cycle is completed in a fortnight.
Damage:
The blow-flies apart from feeding on dead animals, carrion and cadavers also infest meat in butcher shops. Some of the species of blue-bottles, particularly the screw worms, cause myiasis in animals. Wounds and other diseased sites on the body are the most liked for oviposition. The sick cattle in a herd are the preferred victims.
Control:
(i) Larvae may be destroyed in situ by spraying the wounds with chloroform- water to induce them to leave the tissue or by removing them with forceps. Thereafter, the wounds should be dressed with some disinfectant and a repellent like pinetar.
(ii) Proper disposal of carcases, treatment with larvicidal chemicals and trapping of flies with baits may be carried out in order to suppress the population of flies.
10. Horny or Leathery Flies, Hippobosca Maculata Leach (Diptera: Hippoboscidae):
These flattened horny or leathery flies are permanent parasites of horse, goat, sheep, dog, etc. They have long and stout legs, provided with well-developed tarsal claws adapted for clinging to the hair of their hosts.
The common parasites of farm animals are placed in four genera, viz. Lipoptena, Melophagus, Pseudolynchia and Hippobosca. Lipoptena caprina Austen is found on goat, Melophagus ovinus (Linnaeus) on sheep and Pseudolynchia maura Bigot on pigeons. The more abundant species in northwestern India are Hippobosca maculata on bovines and equines, H. capensis Olfers on dogs and H. camelina Leach on camels. The flies are extremely tough and difficult to kill, except by decapitating them.
Life-Cycle:
Their most characteristic feature is that they retain their young inside the body till they are ready to pupate. The matured larvae are deposited on the ground for pupation. The pupal period lasts 24 days and the adult flies live for 28 days. They feed on the blood of the host throughout their life.
Damage:
It appears that the bite of these flies is not painful to the host and it only causes annoyance. Since blood does not ooze from the site of the bite, the muscids and other flies do not gather there. In certain localities, however, the fly population may be so high that the host may lose much blood and die.
Control:
(i) The pest can be controlled by sprinkling malathion 5 per cent dust on the back, neck and flanks of the animal every 10-14 days, if needed,
(ii) A single spray treatment of draught cattle with 0.05 per cent lindane is very effective for controlling the leathery flies.
11. Poultry Stickfast Flea, Echidnophaga Gallinacea (Westwood) (Siphonaptera: Pulicidae):
It probably occurs all over India, and has been recorded from Uttar Pradesh, Maharashtra, Karnataka, Tamil Nadu and Kerala. The adult is a small delicate flea without any comb. The front is angulate and the thoracic tergites together are shorter than the first abdominal tergite.
Life-Cycle:
The adult flea attacks the bare parts of the body of a fowl, such as the comb, wattles, and around the eyes and beak, particularly of the young chicks. These insects bury their mouthparts in the flesh of the bird and remain fixed in that position. The egg-laying by adults begins after 6-10 days of attachment of the host.
The oviposition usually takes place at night. The eggs hatch in 6-8 days. The larval period is completed in 14-31 days. When mature the larvae bury into debris and pupate inside cocoons. The adults emerge in 9-19 days. When the adult becomes 5-8 days old, it attaches to the host. The male flea lives for about 2-6 days after mating but the female lives up to 6 weeks on the host.
Damage:
When the infestation is heavy, the young birds become dull and droopy, and some of them may even die. In older birds, prolonged infestation makes them anaemic which decreases egg production.
Management:
The infested birds may be dipped in 0.05 per cent carbaryl or malathion or dusted with 5 per cent carbaryl or malathion dust. These dusts may also be sprinkled on the litter in poultry houses.
12. Cattle Ticks, Hyalomma Anatolicum Koch and Boophilus Microplus (Canestrini) (Acari: Ixodidae):
Ticks are very important external parasites of cattle, sheep, goat, horse and other farm animals. Many species attack cattle. Of these, B. microplus and H. anatolicum are very common in India. Unlike insects in which the body is divided into three parts (head, thorax and abdomen), ticks have a fused head and thorax.
Damage is done by larvae, nymphs and adults. They suck blood from their host. Larvae are small creatures having three pairs of legs, whereas nymphs and adults have four pairs. The ticks measure about 2.5 × 1.5 mm in size. They increase in size enormously after gorging themselves with blood.
Life-Cycle:
Ticks remain active throughout the year. Eggs are laid in cracks and crevices in buildings or in the soil. A single female may lay more than 2,000 eggs in clusters. They hatch in 2-6 weeks, depending upon the season. The six-legged larvae attach themselves to a suitable host, as and when it might happen to pass by their abode. B. microplus, which feeds on cattle, is a single host species and the larvae moult into nymphs and finally into adults on the same infested animal.
Mating takes place on the host and the fully engorged adults drop to the ground. H. anatolicum which feeds on cattle, goat, horse, donkey and camel, is a three-host species. The larvae feed on the blood of the host for 4-7 days, then drop to the ground and moult into nymphs.
These nymphs may then attach themselves to some other animals, feed on their blood for about two weeks and again fall to the ground to moult and develop into adults. The adults attach themselves to still another animal on which they feed and mature. The life-cycle is completed in about 3-5 weeks and there may be a number of broods in a year. H. isaaci, H. ferozedini and H. hussaini Sharif feed on cattle and buffalo.
Damage:
Ticks usually infest the softer portions of the host animal. Most of them are found on skin near the ears, udder and base of the tail, with their heads embedded deep into the skin. They suck blood and transmit several important diseases like tick fever and Texas fever. Tick bites lead to the formation of abrasion marks in grain of the hide which fetches a lower price in the market.
Control:
(i) Ticks should be removed by hand and killed.
(ii) Dust powders containing 2 per cent lindane, 5 per cent carbaryl or 5 per cent malathion are effective.
(iii) Spray of 1 per cent malathion or 0.2 per cent suspension of bromocyclen (Alugan) is very effective against Hyalomma ticks on cattle, camel and dog.
13. Fowl Tick, Argas Persicus (Oken) (Acari: Argasidae):
The fowl tick is distributed throughout the world and it is known to transmit spirochaetosis. This tick also attacks turkey, goose, duck and pigeon. Whereas the adults and nymphs feed at night, the larvae remain continuously on the skin of the host till they are fully developed.
Life-Cycle:
The females lay eggs in batches of 30-100 in cracks and crevices of fowl-houses. Up to 900 eggs may be laid by single female. Depending upon the season, the eggs hatch in 10-90 days. The first stage larva is full-fed in 3-10 days after which it drops off and moults into the first nymphal stage, within one week. In a few days, it refixes itself to the host and becomes replete in a couple of hours and drops off.
After two weeks, it moults and emerges as the second-instar nymph which again engorges itself with blood for 2-3 hours, drops to the ground and after about two weeks moults into an adult. The female deposits eggs only after taking a meal of blood from the host. The adults are very tenacious and may live without food for as long as 3 years. Normally, the life cycle is completed in 5-6 weeks.
Damage:
Apart from causing spirochaetosis through the transmission of Spirochaeta anserina, the tick causes considerable injury to poultry, resulting in the reduction of egg production.
Control:
(i) The poultry houses should be cleaned thoroughly. The hiding places of ticks should be eliminated by removing the rubbish and by closing the cracks and crevices.
(ii) The fowls should not be allowed to roost in trees.
(iii) The wild birds should not be allowed to nest in and around the poulty houses.
(vi) The pest can be controlled by spraying malathion 3 per cent or carbaryl 2 per cent on walls, ceiling and floor. The spray fluid should be forced into the cracks.
(v) The infested fowls may be dipped in 0.01 per cent solution of dichlorvos or malathion or may be given dust bath containing these insecticides.
14. Mange Mite, Sarcoptes Scabiei (Linnaeus) (Acari: Sarcoptidae); Scabies Mite, Psoroptes Communis (Furstenberg) (Acari: Psoroptidae):
The former species of mite (S. scabiei) lives in subcutaneous galleries made in the skin of man and warm-blooded animals. It has a remarkable range of hosts and in the course of its evolution; various varieties have appeared which are confined to specific hosts. On an average, the male measures about one-quarter of a millimetre and the female about two-fifth of a millimetre.
There are several described varieties of these mites, S. s. var. hominus is found on man; S. s. var. bubulus Oudemans infests cattle; S. s. var. caprae Furstenburg attacks primarily goats but also horses and mules; S. s. var. equi Gerlach is found on horses, mules and donkeys; S. s. var. dromedarii Gervais is common on camels and S. s. var. canis Gerlach appears on dogs. The allied species, P. communis has various varieties, namely bos bubulus, ovis, caprae and equi, which attack buffalo, sheep, goat and horse, respectively.
Life-Cycle:
The mites causing Sarcoptes mange mate on the host skin and then the mated females burrow inside the skin, making galleries. The eggs are deposited along with excrement. The nymphs, on emergence, feed inside the galleries and come out after changing into adults. The cast-off skins may be seen at various points in the skin. At room temperature, the mites may survive for about a week and, in this stage, they infest new hosts on contact.
S. scabiei on cattle and buffaloes appear at the junction of the horns and skin, and then they work their way into the distal extremity, reducing the horny tissue to powder, exposing the sensitive core. The diseased animals keep striking their horns against the manger. In sheep, the scabies appears on skin, matting the hair at first and later causing the fleece to drop. On the affected area, a greasy crust is formed. The affected animal keeps moving its lips, shaking its head and trying to bite its own skin.
Unlike the mange mite, which makes galleries, the scabies mite remains in the skin superficially. On coming into contact with the skin, the female lays about a hundred eggs which hatch in 2 days. The durations of the different stages namely larva, female nymph, male nymph and the pubescent female are 2.2, 2.3, 5.0 and 2.2 days, respectively. The life cycle is completed in about 11 days.
Damage:
Sarcoptes mange appears on cattle and buffaloes in the perineal region, the upper thigh and the neck which the animals keep rubbing against any hard surface. In goats, the mange causes general debility and sudden death, sometimes producing a high mortality in herds. In horse, the disease appears on those areas where skin is thin.
Thus, encrustation appears in patches, there being loss of hair. At places the oozing of blood is also noticed. In camel, the mange is noticed in cold weather and the animals that suffer remain in continual agitation and keep biting the skin or rubbing it against the trunks of trees or any other hard surface.
The disease first starts in the groin and gradually affects the flanks, belly, legs, head, neck and back. In pigs, the mange first appears around the eyes and ears and later extends to other external parts of the body, including the inner side of the thighs. The disease is rare in pet dogs, but is sometimes noticed in stray dogs, which, if touched, can infest human beings also.
The cattle and buffaloes suffering from psoroptic scabies keep striking their horns on the manager, caring little for food and, thus, their milk yield is reduced. In sheep, the scabies spreads over the body and causes loss of valuable fleece and also reduces weight of the animal. The goats infested with this mite give up feeding, keep scratching their ears and eventually start going round and round, showing occasional symptoms of fits. They ultimately die. In horse, the upper part of the neck and the tail show this disease.
Control:
(i) Repeated application of powdered sulphur in vegetable oil base controls the disease.
(ii) Two body-washes at 7-day intervals with trichlorphon 0.25 per cent are recommended against mite on buffalo calves. Five washes of 0.4 per cent carbaryl or 0.5 per cent malathion emulsion on dogs at 7-day interval are also effective.
15. Dog Mite, Demodexis Canis Leydig (Acari: Demodicidae):
This mite measures about 0.25 mm in length and causes a serious disease, follicular mange, of dogs all over the country. Although this species lives predominantly on the domestic dogs, but can occasionally infest humans.
The mite occurs in the hair follicles and occasionally in sebacious glands of various other mammals as the dogs lack sebacious glands.
As the mite is located deep in the dermis, transmission is usually only possible via prolonged direct contact, such as mother-to-pup transmission during suckling. As a result, the most common sites for early appearance of demodicodic lesions are the face, muzzle, forelimbs and periborbital regions.
Demodicosis can manifest as lesions of two types- squamous- which causes dry alopelia and thickening of the skin; and pustular-which is the more severe form, causing secondary infection (usually by Staphylococus), resulting in the characteristic red, numerous pustules and wrinkling of the skin.
Control:
There is no satisfactory treatment although the following preparations are said to have given good results:
(i) Rotenone 1g, alcohol 50 ml, acetone 10 ml and water 40 ml.
(ii) An ointment made of β-naphthol 4g, sublimed sulphur 8 g, balsam of Peru 30 ml and petroleum 30 ml. The mixture is to be applied daily or alternate days on the affected parts.