Karachi: a hub of house flies By Dr. Abdullah G Arijo


Recent rains, on one hand, has virtually ruined infra-structure across the country in general and Karachi in particular, house flies, on the other hand, have breed extra-ordinary and taken over rest of the pests. The organism has both medical significance in acting as mechanical and biological vector for quite a few viral, bacterial, protozoal and fungal diseases, dysentery (bloody faeces) being on top. The fly has short life cycle on a month and has great reproductive potential, a tool of success.

The house fly is a recognized insect. This species mostly found in connection with humans. It is mainly common species of large and small ruminants including poultry farms, horse stables and houses. House flies are not only producing irritation, but they also play a major role in transporting pathogens, which leads to organisms sick. Due to, too much fly populations their effect is not only an irritant to farm workers but, whenever they are nearby human being habitations; a public healthiness problem could occur.

The common housefly is a famous mechanical vector of various organisms, which are mostly responsible to transmit pathogens and parasites. Approximately 100 different pathogens are linked with the house fly. They could cause many diseases in humans and animals, including anthrax, trachoma, leprosy, T.B, Q-fever, bacillary dysentery and infantile diarrhea. These pathogens are taken up by flies from dirty areas, pollutant sewage water and other sources of filth and attached with on their mouthparts, through vomits, faeces and infected body surfaces to human being and animal food (Azizi et al., 2014).
Mostly use of chemicals, which kill the insect is not only harmful to the environment and have unwanted effects on non-target organisms, but its long term use also leads to development of resistance among insects. The house flies creating nuisance and affects the healthiness of the animals in the farm, but also become infuriation to the workers of the farm and the people who live in the villages nearby the farms of animals. In poultry houses the manure accumulates in commercial cage-layer houses are the major resource of attraction for the house flies. These flies play a vital role and act as a vector to various disease-causing organisms and thus possess a great threat to the working person and poultry health. House flies can grow in wide range of environmental conditions with high reproductive rate and can breed throughout the year. Thus, manage these potential and effective vectors of disease is a serious concern. The house fly control is largely based upon the use of chemicals which kill the insects such as organ chlorines, and pyrethroid. (Thomas and Jespersen, 1994).

It plays a major role to produce many diseases and act as a mechanical carrier of pathogenic bacteria, such as Shigella spp. Vibrio spp, Escherichia coli, Staphylococcus aureus and Salmonella spp.House flies have resisted human being attempts to control them since the distant past, and the worldwide problem of house fly resistance to conservative insecticides has resulted in renewed interest in biopesticides as another management tools to conservative insecticides. However, they have continued to pose a serious health threat to human beings and livestock by transmitting many infectious diseases (Bharkadet al., 2013).

Controlling house files have always been the focus of attention in scientific community, however, such challenging situation requires a management strategy to interfere with the insect development in order to maintain adult stage population as lower as possible through controlling larval stage population. Due to the high price of chemical pesticides and the ecological hazards as a result of pesticide usage had been encouraged by scientists to seek less harmful and cheaper pesticide groups. Considerable efforts have been made to synthesize an alternative to overcome this problem. Botanical products have become more well-known in assessing present and future pest control alternatives. Numerous plants have been reported about their latent insecticidal actions on different stages of M. Domestica via crude extract or extracted active compounds. Many results also showed their effects on metamorphosis or emergence or fecundity or life span of house flies (Mansour et al., 2011).

The ecological problems caused by overuse of pesticides have been the subject of concern for both scientists and public in recent years. It has been expected that about 2.5 million tons of pesticides are used on crops each year and the world-wide harm caused by pesticides reaches 100 billion annually. The reasons for this are twofold: a) the high toxicity and no biodegradable properties of pesticides and (b) the residues in soil, water resources and crops that affect public health. Thus, on the other hand, there is need to search the new specifically selective and eco-friendly pesticides to solve the problem of long term toxicity to mammalians and, on the other side, study must be carried out on ecological friendly pesticides and develop techniques that can be used to reduce pesticide employ while maintaining crop yields (Suresh et al., 2008).

To utilization of plant and animal parts for medicines has long been in survival and is generally documented in records kept very old in India, China and Egypt. These very old local practices were exposed by a series of “trial and error” which they could not be substantiated by approval scientific theories (Taiwo et al., 2004).

Onions and garlic are underground modified stem. They are tasty ingredients in food items and help to keep away harmful insects. The Sulphur compound in the onion keeps to producing peculiar odour, which acts as a housefly repellent. There have been attempts to develop different concentrations of onion with water in a spray bottle and then spray on surrounding environment in order to keep the harmful insects away. Many plants are known to have repellent effect on specific insect species, onion being an ideal one, due to repellent activity, there is increasing trend on attempting to repel dangerous pests and to avoid use of chemicals regarded as bio hazardous (Brickell and Christopher., 1992).

In the recent scenario, house flies may be controlled, if not eliminated by mass counselling and application of pest management through spraying at the broad-spectrum level. This must be a repeated activity or flies will breed at broad-spectrum scale and will because of infectious diseases.

Here I share experimental data obtained by my postgraduate student, concluding that spray of onion extract inside house may help repel house flies from houses.