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Housefly as Vector

Geetanjali Mishra

Associate Professor

Department of Zoology

University of Lucknow

Lucknow

VECTORS AND THEIR CONTROL

Vectors may be simply defined as any agent that acts as an intermediate carrier or alternative for a pathogenic organism and transmits it to a susceptible host.

Two types:

• Mechanical: Physically transmit

• Biological: Life cycle of the organism should be advanced in the host or they should multiply in numbers

Thus, a large number of including several work as vectors and facilitate the of disease causing organisms from one host to another. Some of the common vectors: , Anopheles, Culex, Aedes, Pediculus, , Phlebolomus, Glossina, etc.

1. HOUSE : (Musca nebulo domestica)

Class: Insecta

Divison: Endopterygota

Order: Diptera

Family:

It is world wide in distribution. It is abundant in hot and humid conditions and most common around habitation, filthy and dirty places. It transmits many diseases of man and contaminates our food by its insanitary habits. External Features: It measures 6mm in length. It is dark grey dorsally with yellowish tinge ventrally. It is distinguished from other common by the presence of four dark longitudinal lines on the and one black band on the abdomen. The body is distinctly divided into head, thorax and abdomen, head bears two compound eyes, three ocelli and two aristate antennae, consisted scape, pedicel and flagellum with three jointed hairy process, the arista. The mouth part are sponging type adapted to suck the liquid food, the food canal is formed by labrum+epipharynx and hypopharynx. Thorax bear three pairs of jointed legs located ventro -laterally on each thoracic segments. Mesothorax bears a pair of broad and transparent membranous wings. The hindwings are reduced to drumstick shaped structures, the which possess sense organs and serve as balancing organ during . It produces buzzing sound during the flight, The abdomen is eight segmented in male and nine in female. The last four segments for the genital pouch, and accessory reproductive organs in male and tubular and retractile ovipositor in female. The entire body is covered with hairs. Life Cycle: Sexes are separate. Female is slighty bigger than male.the flies mate within 24 hours of emergence. The flight mate during spring and summer, especially during august and September. Females lay 6-8 days of mating, in clusters on decaying organic matter. Single female lays 500-600 eggs in 5-6 batches in one season. The eggs are small, white and elongate. The legless (apodous) and headless larvae, the hatch in 8-12 hours. Newly hatched is soft, transparent, white and cylindrically elongated worm like. There are three larval . The full grown is 8-12mm in length and creamy white in colour. The larval period lasts for 5-15 days. The immature larva seeks dry place shrinks his body and transforms into a cyrindrically ovoid . During larval skin turns dark brown and functions as a protectivecovering, called the puparium. Pupal period lasts for 4-5 days, thereafter the adult fly emerged out. A generation is completed every two weeks. Economic Importance: is the most important agent in spreading the diseases and is one of the deadliest enemies of humanity, because of being associated with filth of all kinds (scavengers). It contaminates our food due to its insanitary habit of feeding on human excrement, sputum, exudates of sores, diseased bodies, manures etc. The rough and hairy body surface and feeding habits facilitates the transmission of disease causing organisms of: typhoid, dysentery, , T.B., leprosy, trachoma, , gonorrhea and helminthic disease caused by Taenia solium, , Enterobius, Trichocephalus, Ascaris and viral disease (Poliomyletis). It works as both the mechanical and biological carriers of disease germs; i. Because of its insanitary sitting and feeding habits; and rough and hairy body surface, they carry lots of germs of disease to human food/ drinks (mechanical carrier). A single fly may carry 8 to 50 crores of bacteria. ii. Some of the disease germs are ingested by the fly with food. They and multiply in the crop of the fly and transfer them to food by regurgitation (biological carrier). Because house fly cannot ingest solid food and they release (spit) enzymes of liquify the solid food to facilitate it ingestion and in the process germs are transferred.

Control Measures:

1) Prevention of breeding: This is the best approach and can be achieved by: (a) proper and quick disposal of manure, garbage, etc., (b) keeping premise clean and without accumulation of materials, (c) accumulates manures on arms should be either covered or spread in their layers to dry, (d) outdoor toilets should be either dispensed withor at least excreta be covered with soil. 2) Chemical treatment of breeding ground: Disinfectant like lime, borax, copper sulphate, crude oil, formaldehyde etc., should be sprinkled over their breeding grounds to prevent laying. 3) Protection of edibles: (a) all edibles should be kept covered to prevent flies sitting and contamination of food, (b) the edibles having flies sitting on them should not be bought or eaten. 4) Destruction of adults: (a) manual destruction of adults by fly swatter, (b) baiting by formaline and sweetened milk in a saucer or attracting to a mixture of fermenting banana and milk or cheese and sugar and killing with , (c) stretching a wire smeared with boiled resin and caster (flies sitting on wire will die),(d) flit/ finit, baygon, etc., should be used inside the house, (e) 5% DDT, malathion, diazinon , or 2% lindane or chlordane. 5) Biological control a. Natural enemies like entomic pathogenic fungi, nematodes, fire ants, predatory, beetles, , parasitic wasps (not harmful for human and animals), flies (hHdrotaea aenescens ), and birds. b. Other biological control methods include the use of MdSGHV virus, this virus infects both sexes of flies, but the rate of infection in males is rapid. Young flies are not developed in females, it is because of the inhibition of yolk protein transcription and hexamerin production. As compared to healthy flies, infected flies show shorter life span and reduced rate of successful mating,; c. Bacterial (larvae of could be controlled by feeding Bacillus thuringensis to cattle and chickens breeding sites in a manner for release exotoxin d. New strains of bacteria have been discovered in different countries of the world including Korea, Egypt, and South Africa for housefly control due to the acidic conditions (pH) of digestive system of flies or deficiency of receptors for endotoxin e. Fungi like and E. schizophorae. f. Essential oils obtained from plant sources (the use of botanical oils, change in the behavior of houseflies like attraction, repellence, and toxicity on their contact to flies at different developmental stages have been reported. Essential oil possessing specific amounts of 1,8-cinesle, menthol, limonene, and pulegone shows effective toxicity to adult houseflies. g. The essential oils possess fumigant insecticide properties due to the presences of acetyl cholinesterase inhibition and octopaminergic action); and use if insects as predator, parasite, or housefly (histerid beetles and macrochield mites eat up eggs and larvae of housefly population at large scale h. Pteromalid parasitoid that feeds on houseflies at the pupal stage is used as a more suitable biological control agent of housefly population for decades.

Photograph of Haltere

Life cycle of House fly

8-24 hours E 500-600

24 5- ho 15 ur Musca nebulo domestica da s ys (11-22 days)

A

4-5 days

References

Jawaid Ahsan, Sinha, S. P. 2008. A Handbook of Economic Zoology. S. Chand Group Publ.

Khan, A.A. (Editor), 2007. Encyclopedia of Economic Zoology. 2 vols. Anmol Publications Pvt. Ltd. (April 1, 2007)

Shukla, G.S. & Upadhyay, V.B. Economic zoology. Rastogi Publs. 2005. 487 pages.

Nigam, H.C. 2006. ModernTrends in Biology & Economic Zoology. Vishal Publ. Co. 444+xii pages.