Arthropods Theory Notes 22.10.2021 PDF

UNIT-4 (ARTHROPODS OF VETERINARY IMPORTANCE) Syllabus Arthropods: Introduction, general account and classification, general life cycle of arthropods with morphological features of their developmental stages. Important morphological features, general bionomics, life cycle, vector potentiality, path...

UNIT-4 (ARTHROPODS OF VETERINARY IMPORTANCE) Syllabus Arthropods: Introduction, general account and classification, general life cycle of arthropods with morphological features of their developmental stages. Important morphological features, general bionomics, life cycle, vector potentiality, pathogenesis and control of following arthropods affecting animals and birds: Bugs (Cimex). Biting midges (Culicoides), black flies (Simulium), sandflies (Phlebotomus), mosquitoes (Culex, Anopheles and Aedes). Horse flies (Tabanus), Haematopota and Chrysops. Musca, Stomoxys, Haematobia and Sarcophaga. Warbles (Hypoderma), stomach bots (Gasterophilus,Cobboldia), nasal bots (Oestrus ovis,Cephalopina), Bottle flies (Calliphora, Lucilia, Chrysomya), myiasis. Hippobosca, Melophagus, Pseudolynchia. Lice (Haematopinus, Linognathus, Trichodectes, Damalinia, Menopon, Lipeurus, Menacanthus and Heterodoxus). Fleas (Ctenocephalides, Echidnophaga, Xenopsylla, Pulex). Arachnids : General account, soft ticks (Argas, Ornithodoros and Otobius). Hard ticks (Hyalomma, Haemaphysalis, Rhipicephalus(Boophilus), Dermacentor, Ixodes and Amblyomma). Mites (Dermanyssus, Ornithonyssus, Demodex, Notoedres, Sarcoptes, Psoroptes, Chorioptes, Cnemidocoptes and Otodectes). Pentasomida (Linguatula). Study of insecticide or acaricide resistance. ETERINARY ENTOMOLOGY AND ACAROLOGY is the branch of parasitology which deals with insects (flies, lice, fleas, bugs) and acarines (ticks, mites) causing disease or act as vectors in animals. PHYLUM -ARTHROPODA Arthropoda is a greek word meaning ‘arthros’-joint; ‘podos’-leg which refers to the fact that members of Phylum Arthropoda have jointed legs. GENERAL FEATURES OF ARTHROPOD o Bilaterally symmetrical o Segmented body o Compound eyes o Chitinous exoskeleton o Jointed legs o Haemocoel 1  o Haemolymph o Dorsal blood vessels o Ventral nerve cord EXOSKELETON- INSECTS The hard outer covering of arthropod is made of chitin, it forms the Exoskeleton which covers the external surface of the body It passes through the mouth and lines the anterior part of the alimentary tract which is called Stomodaeum It also goes through the anus into posterior part of alimentary canal which is called Proctodaeum Exoskeleton is usually in the form of chitinous plates called Sclerites The dorsal sclerite is called Tergum Ventral sclerite is called Sternum Lateral plate between tergum and sternum is called Pleuron The tergum, sternum and pleuron of each segment are united by more flexible portions of exoskeleton which are termed sutures Casting off the exoskeleton is called Ecdysis or moulting. The main function of exoskeleton: Protection to the internal organs The phylum arthropoda has two classes of veterinary importance (i) Class : Insecta (e.g,) Flies, lice, fleas and bugs. (ii) (ii) Class: Arachnida (e.g) Ticks and mites. EXTERNAL ANATOMY - INSECTS The body of an insect is divided into three parts, (i) Head (ii) Thorax and (iii) Abdomen. HEAD - INSECTA o Paired antenna, Compound and simple eyes, Mouth parts 2  o The head is an ovoid or globular capsule. The dorsal wall is formed by vertex and lateral wall by genae (Cheek). The anterior wall of the capsule is formed by frons (fore head) which articulates dorsally with the vertex and ventrally with clypeus. The incomplete posterior wall is known as occiput which articulates with neck. COMPOUND EYES (i) The compound eyes are made up of individual eyes that consist of large number of hexagonal shaped facets termed Ommatidium which is the basic unit of compound eye. These ommatidia have rods and cones which will help in the vision. Holoptic eyes: Compound eyes are very close to each other or may meet one another in the mid line (e.g) Male insects. Dichoptic eyes: The eyes may be wide apart (e.g) female insects. 3  (ii) Simple eyes or Ocelli (singular-ocellus ) : These are photoreceptors (not for vision) and arranged as an inverted triangle on the dorsum or vertex. ANTENNA All the insects have filamentous sensory organs called Antenna (absent in arachnids). It is a segmented structure, inserted between the eyes and varies from species to species. It is composed of three jointed filaments 1. The first segment attached to the vertex is called scape. 2. The second segment is the pedicel which has an olfactory and auditory apparatus called the 'Organ of Johnston'. 3. The third segment is collectively called the flagellum Types of Antenna: There are 16 types of antenna, which help in identification of insects. The most common types found in insects of veterinary importance are (i) Plumose type: Large numbers of bristles on the antenna is called plumose antenna. (e.g.) Male mosquitoes. (ii) Pilose type: Few numbers of bristles on the antenna is known as pilose antenna. (e.g.) Female mosquitoes. (iii) Aristate type: A specillized bristle on the third segment of antenna is called as arista, which is sensory in function. Functions of Antenna: (i) The segmented antenna has specialized bristles which are sensory and tactile in functions. (ii) It is an organ of smell and hearing. MOUTH PARTS 4  These consist of the labrum (upper lip) which forms the upper boundary of mouth and the labium (lower lip) which forms the lower boundary of the mouth. Between these two structures are two pairs of biting jaws, an upper pair, the mandibles, and a lower pair, the maxillae. On the underside of the labrum there is a small membranous structure, the epipharynx which bears the organ of taste. These two are frequently fused to form the labrum - epipharynx. On the upper surface of the labium is a further membranous structure, the hypopharynx, which bears the opening of the salivary duct. There may be modifications of these parts according to the habit of feeding. The labium may be greatly expanded for imbibing liquid food ( House fly) or all parts may be modified into fine piercing stylets (mosquitoes) Types of mouth parts : 1.Based on structure:  (i) Prognathus - projecting forward (e.g) Lice, Sheep ked  (ii) Hypognathus –Projecting downward (e.g) Mosquitoes, Musca, Fleas  (iii) Opisthognathus - projecting backward (e.g) Bed bug. 2. Based on feeding habit: (i) Lapping/sponging/sucking type-(e.g) house fly (Most of Cyclorrhapha flies have lapping type mouth parts) (ii)Piercing and sucking type - (c.g) Mosquitoes, phlebotomus, Culicoides, lice, fleas, and bugs. (iii) Cutting and sponging type - (e.g) Tabanus sp., Simulium sp. (iv) Chewing type - eg. Lice 5 THORAX - INSECTA Has three segments 1.Prothorax 2. Mesothorax 3.Metathorax Appendages on the thorax include o 3 pairs of walking legs, one for each segment o 2 pairs of wings (Meso and Meta thoraxic wings) ABDOMEN - INSECTA Clearly segmented, soft and membranous Copulatory claspers are seen in male on the last abdominal segment called aedeagus while in the females called Ovipositor. LEGS Consist of basal coxa by which the leg is attached to the body, followed by trochanter, femur, tibia and tarsus. Last tarsal segment is provided with a pair of claws. Below each claw a pad like structure called pulvilli is seen. WINGS Normally two pairs-on meso and meta thorax wings In Diptera, the posterior pair is reduced to a pair of balancers or halteres Wings are supported by veins or breathing tubes (trachea) called wing venation. Identification of insects is based on wing venation. INTERNAL ANATOMY - ARTHROPODS The internal body cavity - haemocoel is filled with blood called haemolymph ALIMENTARY/DIGESTIVE SYSTEM - ARTHROPODS Includes o Anterior - stomodaeum or foregut o Mesenteron or midgut 6  o Porterior- proctodaeum or hindgut Lined by chitinous exoskeleton. Anterior part of alimentary canal may have pharynx, behind this, a dilatation -the crop, followed by proventriculus. The proventriculus acts as a valve to prevent regurgitation and may have "teeth" to aid in the grinding of food particles (flea) This leads to mesenteron or mid gut. It is flask shaped and its anterior narrow part is called cardia.It is here that food is digested and absorbed. In midgut, food is covered by a membrane is called Peritropic membrane that prevents pathogens enters into body. The proctodaeum consists of an anterior ileum, colon, dilated rectum and anus. It opens out into exterior through anus. The main function of the hind gut is the absorption of water from the faeces and urine. Urine passes into the hindgut from the malpighian tubules (Excretory system of insects), which open just behind the midgut. Faeces are excreted as dry pellets and nitrogenous waste as uric acid. CIRCULATORY SYSTEM - ARTHROPODS Heart is an enlarged tubular dorsal blood vessel organs are bathed in hemolymph Blood is propelled through the body by the heart 7  It is enclosed in a compartment called pericardium Pericardium is like rest of haemocoel filled with hemolymph When heart sucks hemolymph through openings on its wall called OSTIA and expels it again forwards to head. RESPIRATION - ARTHROPODS Through spiracles in the exoskeleton - exchange of gases takes place. e.g. parasitic mites Through Gills o Portions of body modified to form gills. e.g. Aquatic larvae of mosquitoes Through organs developed which can take air into interior of body o Air breathing organs include  Lung books e.g. Scorpions /spiders/Crabs  Trachea e.g. Ticks, insects  Tracheal lungs e.g. larvae of Hypoderma  Tracheal system has large thin walled dilations- air sacs e.g. Lucilia NERVOUS SYSTEM Head has dorsal brain then connected to a double ventral nerve cord Each thoracic and abdominal segment has one ganglion (i.e. 3 thoracic ganglia and 11 abdominal ganglia). EXCRETORY SYSTEM - ARTHROPODS Excretory organs of insecta are called Malpighian tubules which are arranged in a ring around alimentary canal at the junction of mid gut and proctodeum Coxal glands and Malpighian tubules used for excretion by Arachnida (Ticks) 8 REPRODUCTIVE SYSTEM - ARTHROPODS Male : The male has a two testes and from these arise the vas deferens which conduct the sperm to the seminal vesicles for storage. The common duct (ejaculatory) opens into aedeagus which conduct the sperms into the female. Accessory sex glands are seen on either side of the ejaculatory ducts which secrete a fluid for lubrication of aedcagus. External genitalia are the aedeagus, which is provided with claspers. Female : The female has two ovaries which consist of groups of ovarian tubules, all arising from an apical filament. The ducts unite to form a common duct which bears the receptaculum seminis that ends in ovipositor. Accessory glands are usually present whose secretion serves to attach the eggs to the hair of the host. Oviparous - Flies that lay eggs (e.g) Mosquitoes, Tabanus, House fly etc. Larviparous - Flies that deposit larvae (e.g) Oestrus ovis, Sarcophaga sp, Sheep ked (Melophagus sp) Pupiparous - Flies which give birth to larvae that are ready to pupate (e.g) Hippobosca sp. METAMORPHOSIS - ARTHROPODS Change in form of the insects associated with ecdysis or moulting is called Metamorphosis Two types of Metamorphosis, o Complete Metamorphosis o Incomplete Metamorphosis o Unchanged or Metamorphosis is absent. e.g. silver fish Complete Metamorphosis Incomplete Metamorphosis (Holo-metabola) (Hemi-metabola) Examples: Flies, Fleas Examples: Lice, Bugs, Ticks & Mites, LIFE CYCLE 9  Egg-nymph-adult e.g. lice & bugs Egg-larva-pupa-adult (Flies& Fleas) Egg-larva-nymph-adult- ticks & mite Complete metamorphosis is when the Incomplete metamorphosis is when the adult stages are totally different from the adults and immature stages resemble one immature stages morphologically another morphologically The young one is called larvae. Larvae/Nymph It is immature stage of insect Larvae have ocelli only. Nymph and adult have compound No compound eyes eyes There is a prolonged resting phase- No resting stage pupal stage HABITAT Adults and immature stages occupy Occupy same habitat different habitats e.g. mosquito Mites larvae/nymph and adult are all larvae/pupae are aquatic while the seen in the skin of host adult is terrestrial(Land) FEEDING HABIT Adults and immature stages feed Similar feeding habits and mouth differently parts Adults and immature stages have E.g. In biting louse chewing mouth different types of mouth part parts in larvae, nymph and adult E.g. Mosquito piercing and sucking mouth part in adult, chewing mouthparts in larvae, pupa non- feeding stage 10 TYPES OF LARVAE Classification of types of larvae is mainly based on the head and number of legs Eucephalus Larvae with distinct head and mouth part. e.g. larvae of mosquito Acephalus Larvae with reduced head (or) no head. e.g. larvae of dipteran flies Polypod larvae Eucephalus (True or well marked head) Thorax with three segments, each with a pair of clawed legs Abdomen with ten segments, the first 5 segments bearing fleshy hooked legs called prolegs It has both thoracic and abdominal legs e.g. Caterpillar of butterflies Oligopod larvae Eucephalus Thorax with three pairs of legs No abdominal legs. e.g. beetle larvae Apodous larvae Acephalus (reduced head) No thoracic or abdominal legs e.g. larvae of house flies/blow flies PUPA It is the quiescent phase between larva and imago (adult) IMAGO 11  young adult insect inside pupa TYPES OF PUPA 1. Exarate or Free Pupa Active pupa The wings and legs of developing adult can be seen externally and they are free from the rest of the body. e.g. beetles (Coleoptera-Order) 2. Obtectate Pupa The legs and wings of developing adult is attached to the body by moulting fluid They can be seen externally The adult emerges from pupa through a ‘T’ shaped opening. e.g. Nematocera and Brachycera-Order 3. Coarctate Pupa Last larval skin is not cast off but forms a puparium or Cocoon inside which adult develops Developing adult cannot be seen externally Young adult emerges out through circular opening on pupal case e.g.Cyclorrhapha (Order) - pupa of house fly, stable fly Reference books 1.Veterinary Entomology by Richard wall and David Shearer 2.Medical and Veterinary Entomology by D.S. Kettle 3.Veterinary Parasitology by J,M,Urquhart 12 4. HELMINTHS ARTHROPODS AND PROTOZOA OF DOMESTICATED ANIMALS by SOULSBY.E.J. L. CLASSIFICATION OF ARTHROPODS 13  Section:Acalypterae Calypterae Pupipara Family:Gastrophilidae 1.Muscidae 1.Hippoboscidae 2.Calliphoridae 3.Oestridae Sub-order: NEMATOCERA (Nemato means long, cera means antenna). Family o Culicidae o Psychodidae o Simuliidae o Ceratopogonidae Culicidae- MOSQUITOES Family: Culicidae Species:  Anophles stephensi  Culex fatigans  Aedes aegypti MOSQUITOES -GENERAL MORPHOLOGICAL CHARACTERS Head 14  Small and spherical Eyes: Large compound eyes, holoptic in males and dichoptic in `females , Ocelli absent Antenna: Long and slender antenna, 14-15 segmented, plumose in males and pilose in females Mouthparts: Piercing and Sucking type Only females feed on blood Females show the presence of a pair of mandibles which are long and needle like –they pierce the skin A pair of maxillae which are stylet like are present Male mosquitoes live on nectar or fruit juices and have reduced (or absent) mandibles and maxillae Thorax Wedge shaped Legs: Three pairs of legs, the third pair is called the floating pair since it does not touch the substrate while resting. Wings: Wings are narrow, lanceolate and bears scales Wing venation is characteristic in that the 2nd, 4th and 5th longitudinal veins are forked Abdomen Long and slender LIFECYCLE Egg -Larva(L1-L4) -Pupa- Adult EGG - MOSQUITOES Laid on water Wide variation in habitat occurs It depends on the individual species preference for presence 15  or absence of decayed material, acidity and alkalinity MOSQUITOES - LARVA Mosquitoes - Larva is called as “wigglers” Four larval stages in the life cycle Larvae feed on algae and other organic matter available in the water Body has head, thorax and abdomen Head bears simple eyes, antennae and hairs. The mouth parts are mastigatory and are surrounded by brushes called the feeding brushes. Thorax is unsegmented and bears hairs Abdomen has 10 segments. Stigmal opening is located at the junction of the 8th and 9th abdominal segments. The opening is called respiratory fossa in Anophelines while in the Culicines it is covered by a tube called the Siphon tube On the ventral aspect of the siphon tube is a row of spines called the Pecten PUPA - MOSQUITOES Commonly called the "tumblers" due to the tumbling movement they exhibit Aquatic, comma shaped The head and the thorax are fused together to form the Cephalothorax On the dorsal aspect of the head a pair of breathing trumpets are seen The 9th abdominal segment shows the presence of a pair of paddles which enable the pupa to move The life cycle is usually completed in a week time-it may be prolonged under adverse conditions Difference between Anopheline and Culicine mosquitoes Character Anophelines Culicines Genus and species Genus : Anopheles Genus: Culex Species: C. fatigans Species: A. stephensi Genus: Aedes Species: A. aegypti Common Names Anopheles is referred to as Aedes aegypti is called the dappled mosquito due yellow fever mosquito to the presence of Aedes albopictus-Tiger dappling on the wings mosquito 16 Difference in the adults Resting Posture Rests at an angle to Rests with the abdomen the surface. The proboscis parallel to the surface while is held forward, thus the proboscis is bent down. proboscis and abdomen are So abdomen and proboscis in a straight line are at an angle to one another Maxillary palp is as long as Maxillary palp as long as Mouthparts the proboscis and not the proboscis and has a club shaped appearance clubbed Male Maxillary palp as long as Maxillary palp is short Female the proboscis and is one third the length of the proboscis Thorax Scutellum Unilobed and crescent Trilobed shaped Accumulation of scales at Wings the anterior border of the No dappling wing giving it a dappled appearance Legs No white bands at the White bands are seen at joints of legs the joints of legs in the case of the Aedes alone Last abdominal segment is Abdomen Last abdominal segment is broad and rounded at the tip narrow and pointed Fly almost a mile from While Culex spp. Can fly Habits more than a mile from the their breeding areas, anthrophilic, nocturnal breeding place Aedes spp. biter, painful bites and Do not fly far from their prefer the ankle of man and breeding area. The bites of in animals the fetlock the culicines are not as region painful as that of the 17  anophelines. Difference in the lifecycle Breeding areas Prefer fresh water such as Culex spp. oviposit in running water, rain dirty, contaminated water water, water used for such as those in the irrigation purposes, drains, and ditches etc., streams, lakes etc., Aedes spp. usually prefers water held in containers, such as tanks, water stored in buckets, rain water in the tree holes, tyres, tins, pots etc., 18 Egg Laid single, boat shaped Culex spp. lays eggs in with lateral floats and masses. The eggs are frills arranged vertically with the One female can lay 40-100 pointed end towards the eggs at a time surface of the water. It’s referred to as the “Egg raft” A female can lay around 200-600 eggs at a time. Aedes spp. lays single eggs. The eggs are cylindrical and reticulated Larvae Absence of siphon tube Siphon tube is long and Larvae lie parallel to the conical in Culex spp.and water surface with the it’s short in Aedes spp. respiratory fossa applied to Larvae hang down the water surface. Palmate vertically from the water hairs present on the body surface. Palmate hairs segments enable the larvae are absent. Pecten is to float parallel to the water present, its short in the case surface. ofCulex spp. while in Aedes spp. its long.. Pupae Breathing trumpets are Breathing trumpets are long short and broad. and narrow. No palmate Abdominal segments with hairs. palmate hairs. Difference in the vector potentiality Humans Human malaria(caused by Avian malaria (Culex sp.) Plasmodium falciparum, P.vivax, P.ovale etc.,) Filariasis in man caused by Filariasis in man caused by Wuchereria bancrofti, Wuchereria bancrofti, Brugia malayi. Brugia malayi. Culex spp. is responsible 19  for the transmission of Japanese B encephalitis virus in children which causes brain fever. Aedes spp is involved in the transmission of Yellow fever virus, dengue, Rift valley fever virus, Chikungunya fever virus, Animals Zika virus Both the genus are involved Dirofilaria immitis in dogs in transmission of Setaria digitata in cattle Dirofilaria immitis in dogs, Setaria digitatain cattle, Eastern equine encephalitis virus and St.Louis encephalitis virus MOSQUITOES – CONTROL –Larva & Pupa Managemental practices This is done by elimination/reduction of the breeding areas Stagnation of water to be avoided –fill up pits with sand Removal of vegetations and weeds over the water bodies Aedes spp. can be easily controlled by covering stored water in buckets or over head tank, water in tree holes can be drained or covered up, proper disposal of tires and other containers that can hold water and be a potential source for breeding of the mosquito Application of kerosene on water surface suffocate the mosquito larvae Biological control Fishes such as Gambusia (Mosquito fish), Guppies,Gold fish,Cat fish, tadpoles and frogs feed on the larvae of mosquito Predators such as birds, bats, naiads of dragon fly, spider on adult mosquitoes Toxorhynchites spp -Elephant mosquito feed particularly on larvae of the Aedes mosquito species. Spray of Bacillus thuringiensis (Bacteria)–in water kills larvae of mosquitoes 20  Two species of fungi can kill adult mosquitoes: Metarhiziumsp and Beauveria sp. Sterile male insect technique- Large numbers of male insects are made infertile using gamma radiation. These males are then released into the wild and allowed to mate with females and progeny will be sterile. Chemical control Spraying insecticides is not recommended in fresh water sources – however, the insecticides can be sprayed in sewage, drains etc to control the larvae Spraying of paris green mixed with kerosene is a safe larvicide. Methoprene (Insect growth regulator-IGR) – Larvicide- interferes with natural growth hormones in mosquito larvae, preventing its development. MOSQUITOES – CONTROL -Adults Use of nets, impregnated nets, repellents on individuals DEET (N,N-Diethyl-meta-toluamide), or diethyltoluamide (Odomos) is the most common ly used Mosquito repellent. It is a slightly yellow oil intended to be applied to the skin or to clothing, and provides protection against mosquitoes, ticks, fleas, chiggers, leeches, and many biting insects Use of insecticides in the form of mats, coils, vapourisers and sprays Currently used insecticides are the synthetic pyrethroids. Mosquito control professionals apply pyrethroids as an ultra low volume (ULV) spray. ULV sprayers dispense very fine aerosol droplets that stay aloft and kill adult mosquitoes on contact. Pyrethroids used in mosquito control are typically mixed with a synergist compound, such as piperonyl butoxide, which enhances the effectiveness of the active ingredient. Note: Nilavembu Kudineer, also called Nilavembu Kashayam, is Siddha Medicine recommended for prevention and management of all types of viral infections/fevers. It acts as immunostimulant and immunomodulator, which boosts immunity and modulates defense response in the body, which helps to protect from infections and their complications. It also plays a protective role in dengue fever and chikungunya. It is very popular medicines among people using Ayurveda and Siddha Medicine. Psychodidae-SAND FLIES 21  Family : Psychodidae Genus : Phlebotomus Species : P.argentipes, P.sergenti and P.papatasii o Small hairy flies about 2.5 mm in length o Wings heavily clothed with hairs/scales so venation is obscured, wings are held roof like over the abdomen during rest o Referred to as Sand Flies/Moth Flies/Owl Midges SAND FLIES - MORPHOLOGY Small, like miniature mosquitoes 2-3 mm long, rarely 5 mm Light yellow to grey in colour- hence the common name sand fly Body densely covered with hairs Head Elongated, hangs down from the thorax Eyes: Conspicuous large dark compound eyes-hence the common name owl midges Antenna: similar in both males and females - Moniliform (with a beaded appearance), 16 segmented Mouthparts: adapted for piercing and sucking Palps: pendulous, hairy and 5 jointed Thorax Raised/arched/humped, covered with hairs Wings: large lanceolate, held roof like over the abodomen. 2 nd longitudinal vein- forked twice. Legs: long slender and stilt like covered with hairs Abdomen Long, 8-10 segmented, and covered with hairs 22 LIFECYCLE- SAND FLIES Egg -Larva(L1-L4) -Pupa- Adult Breeding habitat o Cracks, crevices, holes in the wall, rocks o Non aquatic o Dark, moist areas with decaying organic matter SAND FLIES - EGGS Ellipsoidal in shape, 0.3 to 0.4 mm long with rounded endsShow the presence of shining longitudinal black wavy lines, raised slightly and joined by slender cross lines 40-50 eggs are laid in a lifetime by the female fly SAND FLIES-LARVAE Eggs hatch in 1-2 weeks, the emergence of the L1 is by using the egg breaker situated at the anterior end Larvae feed on faeces of lizard and other animals, decaying organic matter and even dried leaves They have a distinct sclerotized head (Eucephalus) Eyes are absent They have 12 segments, 3 thoracic and 9 abdominal All segments have feathered hairs resembling match stick Terminal segments have the characteristic caudal bristles, 4 bristles in L 3 and 2 in L 1 and L 2 The first seven segments possess small false legs called the Pseudopods SAND FLIES - PUPA Pupal stage lasts for 1 to 2 weeks 23  Last larval skin is not discarded, so the pupa remains in an upright position with the last larval skin attached to it It has a triangular head and a curved abdomen It resembles a miniature ram since the long antennal sheath curves below its eyes making it to look like a rams horn SAND FLIES - HABITS Females suck blood while the males feed on plant juices Active at night and hides during day time They are weak fliers and make short hopping flights Seen only in the ground floor of buildings Females bite dogs, men, rodents, reptiles, lizards and other vertebrates In India, life cycle is completed in one and a half to two and a half months time SAND FLIES - EFFECT ON THE HOST Direct Nuisance due to the bites at night Indirect Phlebotomus argentipes-vectors for the protozoan Leishmania donavani (which causes visceral leishmanosis) Phlebotomus sergenti is the vector for Leishmania tropica (which causes cutaneous leishmanosis) Sandfly fever or Papatasi fever due to a virus which is also transmitted by this fly SAND FLIES - CONTROL Removal of dense vegetations to discourage breeding of the flies Mosquito eradication measures also enable control of Phlebotomus species 24 SIMULIDAE- BLACK FLIES Family: Simuliidae Genus: Simulium Species: S. indicum Common Name: Black flies, Potu fly (Himalayas), Buffalo gnats, Turkey gnats Small, dark (hence the name black flies), squat bodied, thick set flies Hump backed, larger than the ceratopogonids BLACK FLIES - MORPHOLOGY Body covered with short golden or silvery hairs Head Eyes: Kidney shaped compound eyes, dichoptic in females and holoptic in males Antenna: Short, thick, cigar shaped which projects forward (resembles the horn of a buffalo and hence the common name) o 11 segmented, compacted and is moniliform or beaded in appearance o Not plumose or pilose- bare Palps: 5 segmented, pendulous, longer than the proboscis Mouthparts: Piercing and sucking type in female Thorax Humped over head Wings: short, broad with large anal lobe Well developed anterior veins, weaker cubital and median veins (posterior veins) Abdomen Male terminal compact and inconspicuous 25 BLACK FLIES- LIFECYCLE Egg- Larva (L1-L6-9)-Pupa- Adult. Breeding site Running water, ranging from torrential mountain streams to slow moving lowland rivers In India seen in the waterfall areas of Himalayan mountains and in Tamil Nadu recorded at Kuttralam, Nilgiri and Palani hills. BLACK FLIES - EGGS Laid during the afternoon and evening times, laid in batches of 200-800 Communal egg mass is common Laid on water/objects close to the waterline or in areas wetted by water or in the splash zone 100-400 μm in size, long ovoid triangular in shape and covered with a gelatinous sticky substance Hatch in 3-4 days or even 12-14 days BLACK FLIES – LARVAE Whitish or greenish in colour 6-9 larval stages, mature larva is 4-12 mm long, elongate, Indian club or hour glass shaped body 26  Prominent pair of cephalic fans (labral fans) which aid filter feeding by the larvae Larvae are anchored to the rocks by means of the thoracic and abdominal prolegs, these are provided with a circlet of hooks which enables adhesion with the substrate Mature larva is recognized by a gill spot on either side of the thorax Larva is also provided with 3 pairs of retractable anal gills Larvae are carnivorous and predacious on aquatic organisms BLACK FLIES – PUPA The larvae moult 6 times to become pupa Obtectate pupa Triangular cocoon BLACK FLIES - HABITS Adult females suck blood, attack in swarms They are opportunistic feeder; feed either on human or animals. PUPA They are diurnal, exophilic and exophagic body BLACK FLIES - EFFECT ON THE HOST Direct Effect Annoyance, painful bites resulting in severe reactions which may lead to death of an individual Petechial haemorrhages especially on areas of fine skin, oedema of throat and abdomen is common Flies enter the natural orifices especially the nose, eyes, ears and mouth of individuals The flies attack in swarms and gadding is seen in animals Milch cows are badly bitten and the teats are bloody and blocked or so sore that they do not tolerate milking, calves cannot suckle Repeated biting in man results in a syndrome called the black fly fever. This is characterised by headache, fever, sweating, shivering, nausea, swelling and 27  tenderness of the lymphnodes, aching joints, lassitude and psychological depression Indirect Effect (vector potentiality) Transmits Leucocytozoon smithi in turkeys and L. simondi in ducks Intermediate host for Onchocerca gutturosa in cattle and O. volvulus of man which is very important since the filarid is the cause of river blindness in man It also transmits eastern equine encephalitis virus and vesicular stomatitis virus in cattle CONTROL - BLACK FLIES Very difficult since the flies breed far away from habitations and the flies can fly 3-5 kms or more in search of hosts. Since they are exophilic, medicated screen can be used in animal houses and animals must be restrained within the houses during the fly season. WHO has recommended the use of a biodegradable product – Abate(Temephos) to be sprayed aerially using helicopters.This is a part of the 20 year programme along the nile river to control river blindness in man. Cholphoxim can be used in areas where resistance to abate has developed. For poultry, dust baths with 0.5% Lindane is recommended. Biological control using Bacillus thuringiensis has been attempted. 28 Ceratopogonidae - BITING MIDGES Family : Ceratopogonidae Genus : Culicoides Species: C.fulvithorax, C.pungens, C.nubeculosus, C.himalayae, C.robertsi Common names : Biting midges, No- see-ums, Punkies o Small inconspicuous flies with wings folded over the abdomen, usually appear as swarms MORPHOLOGY - BITING MIDGES Small, 1-2mm long Head Small with prominent eyes Antenna : 12-14 segmented, plumose in male and pilose in female Mouthparts Piercing and sucking type Maxillary palps : Long Thorax Wings with light and dark pattern, due to pigmentation in the wing membrane-grey with pale spots covered with minute setae Legs are relatively short Abdomen 9 segmented, dull grey to yellowish black or brown in colour Male slender than female with conspicuous claspers Posterior end is rounded in females 29 LIFECYCLE - BITING MIDGES Egg- Larva (L1-L4)-Pupa-Adult Breeding site Wet soil- can be seen in a wide variety of habitats. Individual species utilize only a very limited range of breeding sites Usually can be seen along the muddy shoreline of dairy waste, water ponds and muddy sites contaminated with decaying vegetable matter or even excreta Most species disperse only short distance from their breeding site- important point to be noted for control of these pests, Mostly are crepuscular or nocturnal in habit EGGS - BITING MIDGES PUPA Small, 0.5 mm long, laid in batches of 30-40 They are banana shaped, cylindrical and curved They are dark in colour and hatch in 2-9 days LARVAE - BITING MIDGES Four larval instars They are cylindrical, white with well sclerotized head There are 11 body segments i.e. 3 thoracic and 8 abdominal and are without appendages Larvae show a characteristic eel like or serpentine movement At the posterior end they have 2 pairs of narrow, bifid anal papillae (gills) which are retractable into the rectum This stage lasts for 14-25 days 30 PUPA-BITINGMIDGES 2 - 4 mm, brown and highly chitinised Head and thorax are fused together It bears moderately long, tubular prothoracic horns for respiration Dorsal surface of pupa is covered with spines and tubercles Segmented abdomen ends in a pair of caudal spines with the help of which the pupa moves over the substrate. This is a short lived, non feeding stage Usually seen buried in the substrate and only prothoracic horns protrude on the surface This stage lasts for 3 - 10 days HABITS - BITING MIDGES Females suck blood from both man and animals They are painful biters, crepuscular in feeding habit Following a blood meal, the female usually appears like a drop of blood flying in the air EFFECT ON THE HOST- BITING MIDGES Direct They cause very painful bites and are a source of irritation to man and animals C. robertsi is known to cause an allergic dermatitis in horses in Queensland, Australia, The condition is called as Queensland itch, sweet itch, sweat itch or summer dermatitis The withers and base of the tail of the horse which are bitten by the fly are mainly affected There is an immediate hypersensitivity reaction and intense pruritis is observed in affected horses Further, there is loss of hair and hyper pigmentation Indirect (vector potentiality) They act as vectors for, o Blue tongue virus in sheep o African Horse sickness virus o Bovine ephemeral fever virus 31  Eastern equine encephalitis virus Epizootic haemorrhagic disease in Deer-Emerging disease o Leucocytozoon caulleryi in fowls o Haemoproteus nettionis in ducks, geese etc. They also act as intermediate host for filarid nematodes like Onchocerca cervicalis in horses and O. gibsoni in cattle Dipetalonema perstans-Nematode CONTROL - BITING MIDGES Identification and modification of breeding areas is essential Since Culicoides spp. breed around leaking water troughs- stagnation of water giving rise to the optimum breeding condition of this fly should be prevented For man, clothes impregnated with DEET (N N diethyl m toulamide) is recommended Light/U.V traps are available for trapping Culicoides Baits using a potential attractant - 1 Octane 3 Ol which simulates the body odour of cattle can be made use. Biological control can be affected using Bacillus thuringiensis 32 Sub-order:BRACHYCERA Tabanidae - HORSE FLY Family : Tabanidae Genus : Tabanus Species : T.striatus,T.orientus Common Names: Blind fly, horse fly, gad fly, marsh fly, breeze fly, green heads MORPHOLOGY- HORSE FLY Large and robust fly Head Mouth parts Eyes: Large compound eyes, unicolorous and horizontally banded. Holoptic in males and dichoptic in females. Ocelli vestigial Antenna: 3 segmented. Third segment is the largest and equal to the 1st and 2nd put together. Third segment has a tooth like projection/spur at the base and 4 annulations Mouthparts: cutting and sponging type. Coarse biting parts, mandibles are blade or sword like, maxillae ending in rasp like structures distally. Mandibles cut the skin of the host while the maxillae probe deeper, hypopharynx adds the anticoagulant and blood is drawn into the food channel. The flies are pool feeders Labium ends in labella containing the pseudotracheal membrane which also helps to lap up blood during the feeding process. Maxillary palps are two segmented and prominent The coarse mouth parts and feeding habit of the tabanids frighten the host and hence the tabanids are interrupted while feeding which necessitates the intermittent feeders to visit many animals for engorgement. This intermittent feeding habit of Tabanids makes them potential vectors of diseases 33 Thorax Has longitudinal white stripes Wings are clear with the 3rd longitudinal vein being forked at the apex is hexogonal in shape Abdomen Brown in colour Frequently has longitudinal stripes LIFE CYCLE - HORSE FLY Egg - Larva (L1-L 7-11) - Pupa-Adult. Breeding areas They lay eggs on the soil or vegetation near water EGGS - HORSE FLY Laid in masses of 200-1000, glued to the surface of substrate especially vegetation overhanging water Cigar shaped and water proofed HORSE FLY - LARVAE Hatch out in 4-7 days and drop into the water or the mud 7-11 larval instars are seen They are 11 segmented, maggot like, cylindrical with pointed ends. The larvae are carnivorous and can even bite man They have a distinct chitinous head, 3 thoracic and eight abdominal segments,which has fleshy tubercles. A retractible siphon tube is seen on the 8th abdominal segment. An organ called the Graber’s organ is located on the penultimate segment and is known to have respiratory and sensory functions 34  The 1-7 abdominal segments show the presence of fleshy projections on the ventral aspect which are referred to as the pseudopods (False legs) Terminal abdominal segment has fleshy anal papillae PUPAE - HORSE FLY Obtectate with distinct cephalothorax and 8 abdominal segments Usually seen in the drier parts of the breeding area Have ear shaped spiracles to enable respiration The terminal abdominal segment has six lobes bearing spine like processes called the caudal aster This stage lasts for 1-3 weeks HABITS - HORSE FLY Flies are very fond of sunlight, usually seen in morning hours Flies have a habit of skimming over water and occasionally dipping their bodies into it 35  Females suck blood around the naval area, neck, withers, abdominal region also the back and hindlegs Vicious biters and bite intermittently. They bite indiscriminately and cannot be easily disturbed while feeding and hence the common name blind fly Feed during the hottest parts of the day Flies prefer large animals like horses, cattle but attack man when animals are not available EFFECT ON THE HOST - HORSE FLY Direct Effect The sight of the fly results in panic amongst the animals and they run madly- gadding. This results in the animals getting fractured, abortion in pregnant animals and even death The bites are painful and irritating and may give rise to weals in soft skinned animals The tabanids also feed blood @0.2-0.3ml per day which can result in anaemia Due to the addition of anticoagulant through the saliva of tabanids, blood continues to ooze out of the wound and this attracts other flies like Musca domestica to feed on the oozing blood- which can result in myiasis of the affected animal 17% reduction in feed conversion efficacy has been recorded in animals affected by Tabanid infestation Indirect Effect (vector potentiality) Interrupted method of feeding of Tabanus makes mechanical vector for Trypanosoma evansi and cyclical vector for Trypanosoma theileri Mechanically they can also transmit Anaplasma marginale and the causative organisms of anthrax, tularaemia, rinderpest and equine infectious anaemia CONTROL - HORSE FLY Very difficult since they fly far from their breeding areas Adults Residual sprays of malathion on the shed walls 36  Since the fly skims over water kerosene on water was used earlier to control the flies Ear tags with cypermethrin are effective Avoid the sunny parts of the day for grazing the animals Traps which are coloured black can be placed near breeding areas to trap tabanids Immature stages Biological control using hymenopteran insects such as Hunterellus hookeri and ants such as Telenomus spp., which feed on the eggs of tabanids ******Note: Species of Nematocera and Brachycera have no ptilinal sac and pupa emerge from the pupal case through a “T-shaped split” on dorsal surface where as species of cyclorrhapha emerge from puparium by pushing Ptilinal sac through “circular opening” in the anterior end of pupal case. 37 Sub-order: CYCLORRHAPHA 1.Section: Acalypterae Family: Gasterophilidae-HORSE BOT FLIES Genus :Gasterophilus Species : G.intestinalis(G.equi), G.nasalis, G.haemorrhoidalis Common Name : Horse bot fly, Horse grub fly, Stomach bot Adult stages are non parasitic and the larval stages are parasitic They are seen in the stomach of horses MORPHOLOGY - HORSE BOT FLIES Adult flies are brown in colour, hairy, somewhat resembling bees 18mm long Head Vestigial (non functional) mouth parts Thorax Wing shows the presence of a dark, irregular transverse band running across it Abdomen Ends in a characteristic crooked prominent ovipositor LIFECYCLE - HORSE BOT FLIES Female fly hovers around the animal and oviposits around scapular or the fetlocks region of the forelimb. The eggs are glued to the hair and hatch 5-10 days later only when the horse rubs and licks the area The moisture and friction is essential for the hatching of the eggs 38  The first stage larvae penetrate the mucosa of the tongue and wander for a period of 28 days They moult to the second stage and this stage passes down the pharynx, oesophagus and reach the cardiac end of the stomach where they attach themselves They remain for 5 weeks after which they moult to the third stage mature larvae The larvae remain in the non glandular portion of the stomach for a period of 10 months and the mature larvae is excreted in the faeces Pupation is on the ground and one month later the adult flies emerge Total life cycle takes a year for completion DESCRIPTION OF THE LARVAL STAGE - HORSE BOT FLIES Brown in colour with 2 rows of spines dorsally and ventrally Oral hooks present in all the three stages The posterior spiracle is bean shaped with three wavy longitudinal slits 39 EFFECT ON THE HOST - HORSE BOT FLIES Adult flies The presence of the hovering flies result in gadding in horses and the resultant injury, loss of condition due to improper feeding Larval stages The first stage larvae during its migration in the tongue can result in ulceration of the tongue The second stage larvae may attach itself to the epiglottis, the pharynx and can cause injury to these regions by its oral hooks Since the second and third stage larvae ultimately attach to the non glandular part of the stomach they do not seem to cause much damage However there is a inflammatory reaction to the attached larvae and the stomach mucosa is thickened into a rim around the site of attachment Debility is observed in animals with the infestation and is believed to be due to the toxicity of the excretions and secretions of the larvae The third stage mature larvae is also capable of causing injury by its oral hooks and other spines to the rectal region when its passed out in the faeces TREATMENT - HORSE BOT FLIES Old Treatment Carbon disulphide given in a stomach tube or in a capsule at the rate of 2- 5ml/kg Bwt. after an 18 hour of fasting. Piperazine, Carbon disulphide complexor this mixture with phenothiazine complex @ 110mg/kg is effective against Gasterophilus larvae Trichlorofon in feed or in water by stomach tube @ 39.6 mg/kg Combination of Thiobendazole and Trichlorofon @ 2gm Thiobendazole and 18gm Trichlorofon per 50kg Bwt Dichlorovos @ 26-50mg/kg feed or as a paste @ 20mg/kg Butonate @ 45mg/kg given by stomach tube CONTROL - HORSE BOT FLIES: Sponging the fetlock and scapular areas of horses with a warm insecticidal solution will simulate the licking of horses and thus the eggs hatch. The released larvae are killed when they come into contact with the insecticide 40 Cyclorrhapha 2. Section: Calypterae Family : Muscidae Genus Musca Stomoxys Species M.domestica, S.calcitrans Common name House Fly Stable Fly Stomoxys calcitrans Difference between House fly and Stable fly MORPHOLOGY Common House Fly Stable Fly Name (Musca domestica) (Stomoxys calcitrans) Medium sized, grey in colour, 6 Resembles M.domestica to 7 mm long Head Two large compound eyes Differs in that the arista is Three segmented antenna plumed only on the dorsal Arista bilaterally plumed aspect- has 8-10 bristles upto the tip Mouthparts- lapping and Mouthparts are non retractile sponging type of mouth and a forwardly directed Retractible into the head baton like proboscis. Flies are not blood suckers 41  Biting type of mouth part Flies have prestomal teeth and are blood suckers Thorax Grey with four longitudinal Grey with four longitudinal dark stripes all of which stripes but the lateral pair are extend to the posterior narrow and do not extend border of the thorax upto the posterior border Wing venation is The apical cell is open characteristic in that the Wing kept at divergent angle 4th longitudinal vein curves upwards at about the middle and joins the 3rd vein to form the closed apical cell Abdomen Yellowish round colour Ground grey Five segments of which 4 Yellowish stripes on 2nd and are visible. Presence of 3rd segment which do not median black longitudinal reach the lower border stripe which diffuses on Three circular dots on 2nd the 4th abdominal and 3rd segment. segment in male while in females either side of the abdomen is marked with a diffuse dark band LIFE CYCLE Breeding Garbage, manure- horse Prefers to lay eggs on the areas dung preferred, decaying bedding material of horses- organic debris ,Poultry that is straw which is soiled manure, human excreta, with urine of the horses abundant in rainy season Never breed on human excreta, abundant in summer and autumn Eggs 100-150 eggs are laid at a 25- 50 eggs are laid after time and an average of blood meal 600/lifetime Eggs are dirty white or yellow Elongate creamy white, in colour, 1 mm, with only oval/banana shaped/ 1mm one dorsal ridge or hatching long with two ridge like pleat thickenings on the dorsal Both male and female suck 42  aspect- the hatching pleat blood Larvae Smooth larvae, Acephalus, apodous. The Acephalus, apodous larval stages last 20 days Three larval stages. Larval Similar to Musca spp. except development takes a week that the posterior spiracles are widely separated and are roughly triangular in shape with three ‘S’ shaped stigma slits L3 12 mm long, white, maggot like with 12 segments, 3 thoracic and 8 abdominal segments. o Head with two chitinised black oral hooks with sensory tubercles (2) o Mouth lies between them o Above mouth is a pair of hooks- black and chitinous o Oral (or) mouth hooks- Its part of cephalopharyngeal skeleton. Left hook smaller than right o Last segment largest with obliquely truncated shape o Fan shaped lateral spiracles on Prothorax o D shaped with 3 ‘m’ shaped winding slits- button-posterior spiracles 43 Pupa Last larval skin retained- Pupation in drier part of puparium breeding area Barrel shaped,6-8 mm Similar to Musca spp. Pupal long, creamy then turn stage lasts for 8 days Coarctate , brown, oval shaped Pupa emerges out through circular opening This stage lasts for 3 days Adult Sexually mature in 10-14 Life span- 1 month days after imergence Entire lifecycle is completed Average life span- 1 month in one month Musca adult flies do not Both male and feed on blood – they lap female Stomoxys spp. are blood which flow out of haematophagus wounds etc Entire lifecycle is completed in 7 to 12 days EFFECT ON THE HOST Direct Nuisance, fly worry is Both male and female suck effect known to bring down blood and are painful biters production and feed Anaemia in young animals conversion efficacy Fly worry Feed on wounds etc and result in production of myiasis Indirect Musca is a synanthrope Mechanically effect- and hence has a high transmits Trypanosoma vector vector potentiality evansi potential- Bacterial diseases such as Also is a mechanical vector lity cholera, typhoid, for anthrax, rinderpest, tetanus paratyphoid, T.B, bacteria and poliomyelitis salmonella, E.coli virus dysentery, anthrax etc., Its an intermediate host Viral diseases such as for Habronema majus poliomyelitis and infectious hepatitis Protozoan diseases such as amoebic dysentery, 44  giardiasis Acts as the intermediate host for Habronema muscae, Draschia megastoma, Thelazia rhodesii, Raillietina spp., Choanotaenia infundibulum Mechanical transmission of the eggs of the following is also possibleTaenia solium, Toxocara sp, Ancylostoma, Hymenolepis, Dipylidium caninum and Diphyllobothrium latum Method of feeding Vomit drops: Liquifiable solid foods such as sugars, may be made fluid before it sucked up by ejection of saliva and crop fluid.These fluid drops are called vomit drops, and important in disease transmission. The fly regurgitates or vomits at frequent interval to aid its feeding and while feeding they defecates at random (5-10 minutes).The last tarsal claw ending in pulvillus has full of hairs. These activities are responsible for the mechanical transmission of diseases by contamination of food. CONTROL - HOUSE FLY Managemental Potential breeding sites should be avoided by o Regular removal of manure o Stacking of manure- heat generated kills fly larvae- treating sides of stack with insecticides o Improve sanitation, collect garbage in cans. with tight fitting lids, incinerate garbage/ Hodge's garbage trap/ Babers Fly trap, latrin system on open ground should be avoided o Do not expose food 45  o Use of various types of screens, electrocution grids o Fly line (resin+paraffin oil sticky coat ---> 1,50,000 flies killed within 310 mts long string o Insecticidal use,  Aerosol sprays  Residual sprays for walls, ceilings  Insecticide impregnated cards/strips  Insecticide in solid or liquid baits  Insecticide dust bags "back rubbers"  Impregnated ear traps, tail bands and halters Insect Growth Regulations (IGRs) Cyromazine (Larvadex): it prevents larvae moulting, 1% premix@ 500 gms per tonne of feed. Diflubenzuron :Chitin synthesis inhibitor in larvae @) 0.1% in feed, banned due to presence of residues in meat. Methoprene (Insect growth regulatori-IGF)- juvenile hormone analog and can be used as larvicide. Methoprene does not kill insects. Instead, it acts as an insect growth regulator, mimicking natural juvenile hormone. Juvenile hormone must be absent for a pupa to moult to an adult, so methoprene-treated larvae will be unable to successfully change from pupae to adults. This breaks the biological life cycle. Methoprene is commonly used as a mosquito larvicide used to help stop the spread of the West Nile virus. Methoprene is also used as a food additive in cattle feed to prevent fly breeding in the manure Sugar bait: sugar-0.25% mixed with 1% melomyl Biological Control Steinernema feltiae- a common soil nematode is used to kill fly larvae (box with granules of S. feltiae) Fungus- Beauvaria bassiana on larvae Sopres of Bacillus thuringiensis (BT) on larvae Parasitic wasps/cannibal fly- Predators on Pupa, Hymenopteron fly –on Pupa Family : Oestridae 1. Oestrus ovis - Sheep nasal flies Common name: Sheep nasal fly, nasal bot fly, Sheep head fly, Sheep gad fly 46 Morphology - Sheep nasal flies Dark grey coloured hairy fly Head Arista bare Mouth parts vestigial in adults Thorax Tarry spots are seen on the thorax Muscid type wing venation Abdomen Few black coloured spots are also seen on the abdomen The adult stages are non parasitic while the larval stages are seen in the nasal cavity and other sinuses of sheep/sometimes in goats and man as well LIFECYCLE-SHEEPNASAL FLIES The flies are larviparous The female fly darts at the sheep When the sheep raises its head it deposits a larvae around the nostril of the sheep The first stage larvae then crawls into the nasal passage The larvae moves within using its oral hooks and feeds on the excess nasal discharge produced by the affected sheep The rate of the development of the first instar varies, may take just 2 weeks or could get extended to many months The larvae moults to form the second stage larvae which moves into the frontal and maxillary sinuses, here they develop rapidly and form the third stage mature larvae 47  Generally the third stage larvae is sneezed and the pupation occurs on the ground Usually the larval development is completed in 25 days time but can be extended to 9 months in unfavourable conditions The adult emerges in a month’s time DESCRIPTION OF THE LARVAE - SHEEP NASAL FLIES The first stage larvae is whitish in colour The mature third stage larvae is large, around 3 cm long, with black oral hooks, dark black bands on all the segments on the dorsal aspect On the ventral aspect they have small rows of rose thorn shaped spines The posterior end of the larvae appears large and truncated and the posterior spiracles are very clearly visible The spiracles are brown, ‘D’ shaped with radiating stigma slits EFFECT ON THE HOST - SHEEP NASAL FLIES Due to adult fly The very presence of the flies causes panic in sheep The flies may cause gadding in animals which run madly about resulting in injury and even death of young animals The animal stops feeding, becomes restless, shake their heads or even press their noses to the ground or between other sheep in an attempt to avoid the fly from larvipositing. Since the feed intake is affected the condition of the animals deteriorate Due to larval stages 48  The first stage larvae move around in the nasal passage causing considerable irritation with its oral hooks and spines. This result in the secretion of viscid mucous exudates on which the larvae feed. At times the damage may result in blood tinged mucous being secreted The infected sheep shakes its head, has a nasal discharge and sneezes frequently The nasal region of the affected sheep is dirty in appearance and hence the condition is sometimes called ‘snotty nose’ Sometimes from the frontal and maxillary sinus the second stage larvae may accidentally move towards the brain, causing injury to the brain and even erosion of the skull all of which leads to neurological symptoms in sheep which resemble the condition caused by Coenurus cerebralis. Hence the condition is termed as ‘False gid’ or ‘sturdy’ At times the larvae are deposited by the adult fly on man- frequently affected are the shepherds who are in close contact with the animals The larvae have been reported to have been deposited on the eyes, nostrils, gums, lips etc., of man TREATMENT - SHEEP NASAL FLIES Treatment of the affected animals Rafoxanide (7.5mg/kg ) - drench orally Ivermectin ( 200 micro gram or 0.2 mg/kg BWT Subcutaneously) Closental (10mg/kg BWT) orally –highly effective Instillation of HCH in oil 1-4% into the nostrils or applying tobacco powder into nostril to remove larvae by inducing sneezing. CONTROL - SHEEP NASAL FLIES Feed sheep in narrow troughs The edges of the trough should be smeared in tar. This enables the animals to smear themselves with a repellent Neem oil can also be used as repellent 49 2.Hypoderma bovis - commonly known as Northern Cattle crub 3. Hypoderma lineatum - Ox warble flies Common name : Ox warble fly, Heel fly, Cattle grub fly MORPHOLOGY - OX WARBLE FLIES Hairy flies, resembles a bee Head Vestigial mouth parts Covered with yellowish white hairs Thorax Covered with yellowish white hairs Abdomen Light yellow hairs on the anterior end, darker hairs in the middle, posterior end of abdomen has orange yellow hairs LIFECYCLE - OX WARBLE FLIES 50  The adult fly does not feed and only oviposits on the cattle – usually the lower regions of the hind legs, hence the common name‘heel fly’ A fly oviposits atleast 6 eggs towards the base of the hair of the cattle during the summer months The eggs are spindle shaped and provided with a clasper with the help of which they hold on to the hair The egg hatches in 3-4 days The first stage larvae pierces through the skin and migrates in the inter muscular connective tissues to reach the diaphragm Most larvae reach the tissues of the oesophagus in 4 months time and spend the winter in the submucosal connective tissue of the oesophagus- hence the site is referred to as the winter resting site of L1 larvae The first stage larvae moults to form the second stage larvae which in the beginning of spring, i.e., January migrate towards the dorsal aspect of the body, reaches the subcutaneous tissue of the back and moults to the third stage.The back of the animal is hence referred to as spring resting site of L3 Larvae When the larvae reach the skin of the back an inflammatory reaction results in the formation of swellings The second stage larvae perforates the swelling It then moults and the third stage larvae lies upside down with the posterior spiracle directed against the perforation.The mature larvae have no oral hooks and feeds on the inflammatory exudates in the swelling. These swellings in the skin of the cattle are referred to as warbles or warble stage of infection The warble stage lasts for 30 days It falls off the warble into the soil and pupates Pupation take 1 month time Entire lifecycle is completed in one year DESCRIPTION OF THE LARVAL STAGE - OX WARBLE FLIES Mature larvae lacks oral hook, 2.5 cm in size, presence of fleshy tubercles on all the segments except last, presence of fine spines on the segments Posterior spiracles are kidney or bean shaped with radiating slits 51 EFFECT ON THE HOST - OX WARBLE FLIES Due to Adult fly The characteristic buzzing noise and the persistant ovipositing behaviour of the fly causes panic in cattle called “Gadding” The flies may cause gadding in animals which run madly about resulting in injury, spontaneous abortion, and even death of young animals The animal stops feeding, becomes restless. Since the feed intake is affected the condition of the animals deteriorate There is retarded growth and reduced milk yield Due to larval stage Due to first larval stage o Many larvae enter through the same opening in the skin which results in an exudate from the injured heel region o The opening made by the larvae is prone to bacterial infection and to myiasis-Cutaneous myiasis o The entry holes are oedematous and inflamed Due to the second and third stage larvae o Migration of the larvae through the subcutaneous tissue results in the production of greenish yellow tracts with Eosinophilic infiltrations o The affected beef is called ‘licked beef’ while the gelatinous tracks in the beef are temed ‘butchers jelly’ o The beef is unaesthetic and hence extensive trimming of the affected areas are required before sale, this results in extensive loss to the farmer o The affected beef even following trimming has a short shelf life o The presence of the first and second stage larve in the oesophageal region can cause stenosis of the oesophagus o The presence of the second and the third stage larvae on the back of the animal results in formation of warbles o In addition to being painful to the animal these warbles due to the perforation in them downgrades the quality of hide to a great extent o Accidental rupture of the warbles can result in anaphylactic shock o It can also result in the production of abscess, due to bacterial infection o The perforation can also attract other myiasis producers o Thus carcass and hide depreciation are the most important features of this infestation Abberant host 52  o Man has been known to be affected – result in painful warbles in the chest region o Horses can also be affected CONTROL - OX WARBLE FLIES Mechanical removal of the larvae – can be done when the larvae is mature However attempts to squeeze out the larvae may rupture it which in turn results in localised swelling and abscess formation Insecticides can be used – Ivermectin at 0.2mg/kg or 200 micro gram/kg BWT subcutaneously is highly effective. Dry dressing could be applied to the warble especially to clog the pores which results in the death of the mature larvae CONTROL or PROPHYLAXIS - OX WARBLE FLIES Prevention of the fly from ovipositing is possible if water bodies are available for the cattle to wade into and thus protect their heel region Prophylaxis using vaccine is under study Hypodermin A is a potential vaccine candidate for H.lineatum FAMILY: CALLIPHORIDAE Includes large number of species whose larvae are saprophagus-flesh feeders Family has 2 subfamilies- Calliphorinae and Sarcophaginae CALLIPHORINAE Sub Family : Calliphorinae Genus : Lucilia o Species: L.cuprina and L.sericata Lucilia cuprina Genus : Chrysomia o Species: C.bezziana,C.megacephala  Callitroga hominivorax These are the “blow flies” Metallic blue or green in colour 1. Genus: and L.sericata) Causes blow fly strike 53  Common name: Green bottle flies, Copper bottle flies Flies with bright metallic colours Bright green Primary myiasis producer fly Hypopleural bristles are prominent Mouth,Wing- similar to Musca Adults are free living and larval stages are parasitic Oviparous fly Chrysomia bezziana 2.Genus : Chrysomia (C.bezziana) Common Name: Old world screw worm fly or Blue green bottle fly Medium sized, stout Bluish green fly Four dark stripes on prescutum Face is orange – yellow Mouth,wing- similar to Musca Adults are free living and larval stages are parasitic Lay eggs on living tissue, Never on carcass - (Oviparous fly) Secondary myiasis fly Strike A disease condition called “STRIKE” is caused by the larvae of genus Lucilia sp, and Chrysomyia sp. MATURE LARVAE L3 larva resembles larvae of Musca 10-14mm long Greyish white/pale yellow in colour Anterior extremity with a pair of oral hooks Posterior spiracle on broad, flattened posterior end 54 Posterior spiracle Three long slender slits more or less parallel to one another Two types of larvae recognised o Smooth larvae eg. Lucilia sp o Hairy larvae – has thorn like projections with small spines at the tip eg. larvae of Chrysomyia sp SARCOPHAGINAE Subfamily: Sarcophaginae 3. Genus : Sarcophaga Sarcophaga ruficornis- Flesh flies Common Name : Flesh flies Scavenger fly, Carrion fly Species of this genus lays their larvae in decomposing flesh, wounds and ulcers - Larviparous fly Secondary myiasis fly Sarcophaga dux is seen in lesions in skin of camels, cow and bullock in India Morphology Arista: Bilaterally plumose to middle and rest of its bare Grey 3 longitudinal striped thorax Checker– board marking on abdomen/chess board marking on abdomen 55  Arista- Bilatearlly plumosed to middle and rest of its bare Circular posterior spiracle with 3 longitudinal stigmal slits with imcomplete peritreme Flesh fly lays fully developed larvae on flesh, and fresh wounds of animals and even on dead carcass- Facultative myiasis Myiasis MYIASIS - INTRODUCTION Myia - (Greek word for fly) Hope 1940 coined it and it refers to animal disease due to fly larvae Zumpt (1965) defined myiasis as: o “Infestation of live human and vertebrate animals with the larvae of dipteran fly which atleast for a certain period feed on the host’s dead or living tissues, liquid body substances or ingested food” o In sheep it is referred to as “strike” or blow fly myiasis. Generally caused by larvae of Chrysomia, Lucilia, Phormia 56 57 4. Based on area in which strike occurs Depends on inherent and temporary factors. Sheep are struck mostly in breech region – breech or crutch strike (Merino breed has narrow breech with excessive wrinkling) Around tail – tail strike In Rams and wethers penile sheath has a narrow opening and is soiled by urine resulting in pizzle strike Rams with deep head folds or with horns lying close to head – sweaty condition of head results in poll strike Any wounds can be struck – wound strike When dorsal region of body is affected it is called Body strike (after prolonged wet weather + bacterial activity) leads to fleece rot. Sheep with long, fine wool commonly affected Foot rot also predisposes sheep to strike 58 REASONS FOR MYIASIS Wool of sheep which is kept moist for long time, soiled skin with urine and faeces, these produces decomposition and smell of it attracts the primary flies. The larvae of these flies initiate strike and create favourable condition for secondary flies. These flies liquify the tissue of host and feed on this material developing in the lesion. The central portion of lesion heals by scab formation, with further extension of lesion due to action of larvae. The smell produced from such lesion attracts other flies to deposit the eggs CLINICAL SIGNS IN AFFECTED ANIMALS- MYIASIS IrritationAnimal stands with its head down Does not feed, moves away from flock Attempts to bite affected area If lesion is in tail region, animal stamps or jerks its hind legs, wags its tail Examination reveals discoloured moist wool with bad odour and presence of foul smelling liquid Trimming the wool reveals presence of maggots Progression of disease lead to o Malnutrition o Loss of production o Death A condition called lightning strike occurs when toxaemia / septicaemia occurs wherein the animals dies within few days of strike Animal does not feed properly Weak and debilitated Toxaemic (absorption of toxic substances from lesion) Septicemia and death Financial loss: o decrease in the value of fleece o reduction in meat and milk production Death of animal Labour cost towards surveillance and handling of blow fly strike Diagnosis Clinical signs Trimming the wool helps to reveal the presence of larvae 59 MYIASIS-TREATMENT Ascertain extent of lesion Clip hairs, remove larvae and kill them Dress wound with bland non toxic material MYIASIS - CONTROL Render sheep less attractive to flies by 1. Selective breeding to eliminate folds in poll region / narrow breech 2. Surgical removal of breech folds - Mules operation  A crescentric area on either side of urinogenital area is removed, resultant scarring flattens the skin – effective for breech strike  ‘Chemical mulesing’ -40% phenol when applied along prepuce of young wethers or even in breech region 3. Docking at 4th instead of 2nd caudal vertebrae reduces strike. The short tail produced by docking at the 2nd caudal vertebrae results in a stump surrounded by folds – “rose tail” appearance which is susceptible to strike. A longer tail stump covers the anal area and thus makes it less susceptible 4. Crutching  Regular clipping of wool around tail, breech to prevent soiling of wool 5. Dagging  Removal of faecal soiled wool 6. Burial or burning of carcasses 7. Use of chemicals – Insecticides in wounds infested with larvae 5% coumaphos Ivermectin jetting fluid Oral ivermectin / closantel Chitin synthesis inhibitor – cyromazine is a larvicide Synthetic pyrethroids MYIASIS-BIOLOGICAL CONTROL Wettable powder formulation of Bacillus thuringiensis was found effective against Lucilia cuprina Sterile insect technique (SIT)or Sterile male technique (SMT) o Release of irradiated sterile male flies into a wild population is called SITor SMT o Female that mate with irradiated males produce eggs that fail to hatch 60  o When enough irradiated males are released, a large proportion of mating with fertile female is obtained, eventually driving the species to extinction MYIASIS - GENETIC CONTROL Female killing (FK) system or Genetically impaired female technique (GIFT), o Genetic modification of male flies results in mutations, which affect eye colour o When wild females mate with these genetically altered males a large percentage of the progeny are homozygous for one or more of eye pigment mutations o Its expressed as white or yellow eye colour o These female flies lack the light filtering pigments and hence are blind in daylight such blind females die rapidly in wild MYIASIS - VACCINES PM44 / PM48/PM95 : A concealed antigen, obtained from peritrophic membrane of larval gut of Lucilia cuprina (Sheep blow fly).It is used in vaccination against blow fly strike in sheep in Australia (Under experimental trials) MYIASIS - BAITS AND LURES Screwworm adult trapping system (SWASS) chemical lure, food and 2% dichlorvos For Lucilia spp o Carrion baited traps were used along with insecticide / chemosterilant/ IGR to decrease the population of Lucilia Swormlure is a synthetic chemical attractant used against Cochliomyia spp 61 Series : Pupipara Family : Hippoboscidae o Genus : Hippobosca; Melophagus, o These include flies which lay larvae which immediately pupates o The larvae unlike that of Glossina spp. is incapable of movement, feeding and hence the group has been placed under pupipara HIPPOBOSCIDAE Family : Hippoboscidae Genus : Hippobosca; Melophagus; Common Morphological Characters Body is broad and flattened dorsoventrally Head Large compound eyes are present, ocelli are absent Antenna immovable, single segmented and lies within a pit in the head region Mouthparts are biting type. Porrect The main portions of the proboscis is retracted into the head and generally the narrow terminal part is hidden by the 2 palps Thorax Wings may or may not be present Few of this series do have wings which fall off once the host is reached Wings when present have a characteristic venation- veins crowded in the anterior margin while the posterior portion reveals fine wrinkling Legs are provided with strong claws, since the flies of this series are generally almost permanent ectoparasites of the host the strong claws provide them with firm attachment to the host In species affecting birds additional spurs are observed Abdomen Abdomen is indistinctly segmented, soft and leathery 62 Family : Hippoboscidae (Hippo-horse.Bos-tofeed) Genus : Hippobosca 1. Species : Hippobosca maculata – cattle ked H.capensis–dogked H.equina-equineked Common name: Forest flies, Louse fly, horse keds. MORPHOLOGY Flies are known as pupiparous flies Thorax is marked with clear yellow markings. Veins are crowded together at the anterior margin, legs are provided with powerful claws LIFE CYCLE Female flies are viviparous, oviposit one larvae at a time in sheltered spots off the host such as crevices in mud walls They are creamy white, flattened posterior end with dark spiracular plates The larvae pupates immediately within 4-6 hours Initially its yellow in colour and then turns red black in colour, The pupal stage gives rise to the adults usually in 4 weeks The adult female fly attaches to the host in areas which are thin and hairless and feeds frequently several times In horses it is seen feeding under the tail/genitlia, in cows the tail, udder region, in buffaloes the inner aspect of the thigh, genitalia while in dogs the ears and the neck region are preferred feeding sites They feed for long periods on blood of their hosts and their claws are so efficient that neither the host, nor human beings can dislodge them easily HABITS Active in summer, remain long periods on the host, not inclined to fly although they are strong fliers, usually leave the host to larviposit only 63  They cluster in hundreds in the perineal region, under the tail, between the hind legs to the pubic region. Female fly does not lay eggs but it deposits the larvae singly in dry soil EFFECT ON THE HOST Direct The flies are a source of irritation to newly infested animals Animals which are not used to the fly react adversely No such reaction is seen in animals where infestation is common Blood sucking habit of the fly can result in anaemia in young animals Indirect Transmits Trypanosoma theileri cyclically to cattle CONTROL The flies can be readily controlled by use of insecticides such as synthetic pyrethroids, 0.25% DDVP etc., oral ivermectin 2. SHEEP Genus : Melophagus Species : M.ovinus Common names : Sheep ked, sheep tick fly. MORPHOLOGY Characters similar to Hippoboscidae with the following exceptions, PUPA Head short broad and immovable Wingless Abdomen is large, broad and hairy strong legs provided with claws both sexes suck blood 64 LIFE CYCLE They are permanent ectoparasites and the females glue the mature larvae to The larvae is initially yellowish and soon turns into chestnut brown colour pupa Pupa is ovoid with broad ends and lasts for 21days The female fly survives for 5 months and produces 10-15 larvae during her lifetime The gestation period is 10-12 days for each larva. The infection from sheep to sheep is spread by contact Sheep with dense wool are known to spread the infestation EFFECT ON HOST Direct The keds are permanent ectoparasites and live on the host and suck blood, large infestations can result in anaemia The irritation caused by the biting fly is so great that its feeding is impaired- loss of condition of the sheep The infested animal bites the wool, rubs the body on hard objects which in turn leads to injury to the animal and damage to the wool The bites and the wounds are susceptible to myiasis The excreta of the ked stains the wool, the stain cannot be washed off, so downgrading of wool occurs The skin blemish affects the quality of leather Heavy infestation leads to a condition called ‘sheep cockle or rib cockle’ – the affected skin is pitted due to allergic reaction to the bite of the ked which results in scattered brown nodules on the skin. Another condition reported due to sheep ked is ‘back loss’ wherein the intense irritation leads the sheep to fall on its back to alleviate the irritation, then its unable to rise, suffocates and dies Transmits Trypanosoma melophagium in sheep CONTROL Shearing especially before winter markedly reduces keds Rafoxanide 7.5 mg/kg BWT 65 FLEAS SIPHONAPTERA Order : Siphonaptera (siphon: suck blood from host; aptera- no wings) MORPHOLOGY The body is laterally flattened- an important adaptation for parasitic lifecycle, enable the fleas to move rapidly, minimise damage from host reactions to their bite Thick dark brown chitinous covering- mahogony brown in colour 1-6mm long Females larger than males Not host specific and are found parasitizing a large number of hosts HEAD No compound eyes, lateral ocelli are present on either side of the head (certain authors feel that these are the reduced compound eyes) Antenna is three segmented, short, clubbed and found recessed in deep antennal fossa- another adaptation of the flea to easily move about on the host Mouth parts are piercing and sucking type in the adult and its mastigatory type in larvae Backwardly directed bristles or spines are seen in the gena region- called the genal combs Adaptation to impede flea being dragged backwards due to the host activity 66 THORAX Three segmented – the first segment shows the presence of spines or bristles which are backwardly directed- the pronotal combs Three pairs of legs present, the third pair being long and powerful - aids in the jumping and leaping movement exhibited by the flea-energy for jumping is stored in the pleural arches which are pads of a rubbery protein called resilin Legs end in powerful claws and bristles Two pairs of spiracles are seen on each segment ABDOMEN Shape of abdomen helps to distinguish the sexes Female fleas have both ventral and dorsal surfaces convex while in male the dorsal part is more or less flat while the ventral surface is curved 10 abdominal segments 8 being easily recognisable The 8th ,9th and 10th segments are fused –anal segments 9th abdominal segment in the case of both the male and the female bears a pincushion like dorsal plate called the sensilium or pygidium –this is covered with sensory setae which aids in detection of air currents etc The tergum of the 9th abdominal segment in the male forms the paired manubria – a part of the aediagus or the penis In females the 7th abdominal segment bears a single spermatheca - this is ‘s’ shaped haing a head , a small constriction-base, and a tail portion. This enables species identification in fleas LIFE CYCLE Both male and female suck blood The female produces eggs EGG Large pearly white, glistening and oval in shape 200 eggs produced in 2-4 days time Eggs may be sticky or dry as in E.gallinacea- enabling the egg to roll off the host It falls on the floor or bedding and L1 develops in 2 days time 67  The first stage larvae use the hatching spine or egg tooth to emerge from the egg LARVAE Three larval stages Has a distinct head and 13 body segments, with no difference between the thoracic and abdominal segments Whitish in colour 4-10mm in size Has mastigatory type of mouth parts and feeds on organic matter as well as undigested blood from the adult flea They are semipredatory and attacks damaged adults and even kills them PUPA The third stage larvae spins a cocoon around its body The cocoon is sticky and so becomes covered with dust and debris- camouflaged Remain quiescent till the arrival of the host The pupa emerges from the cocoon in response to the bark of the dog or the footfall of the host Usually the pupa is ready to moult by 1-3 weeks FAMILY : PULICIDAE Genus Species C.canis Ctenocephalides C.felis felis C.felis orientalis E.gallinacea (poultry) - stick Echidnophaga tight flea P.irritans (human flea) Pulex Xenopsylla cheopis - Rat CTENOCEPHALIDES Ctenocephalides C.canis-dog flea, combled flea) C.felis felis- cat flea, combled flea) 68  Important morphological characters include, o Thorax is not reduced and is well developed o Presence of genal combs o Presence of pronotal combs DIFFERENCE BETWEEN C.CANIS AND C.FELIS Difference between C.canis and C.felis is as follows, Character C. felis C. canis Head Long and slender head Short and rounded head Frons Frons elongate Sloping frons Comb First genal comb is as First genal comb is half