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  1. 1. ARDHI UNIERSITY SCHOOL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY DEPARTIMENT OF ENVIROMENTAL ENGENEERING NAME;RAPHAEL, GLORIA B. REG;1689/T2009 ASSIGMENT NO 1Qn; Write on the life cycle of the following , mosquitoes, cockroach, lice,ascarislumbricoides,hookworm and rat.
  2. 2. LIFE CYCLE OF MOSQUITOESMosquitoes are both intermittent parasites and ectoparasites. There immature stages eggs, larvaeand pupae are all aquatic that is they all live in water. The adult mosquitoes on other hand areterrestrial they live in dry land. All mosquitoes must have water in which to complete their lifecycle. This water can range in quality from melted snow water to sewage effluent and it can be inany container imaginable. The type of water in which the mosquito larvae is found can be an aidto the identification of which species it may be. Also, the adult mosquitoes show a very distinctpreference for the types of sources in which to lay their eggs. They lay their eggs in such placessuch as tree holes that periodically hold water, tide water pools in salt marshes, sewage effluentponds, irrigated pastures, rain water ponds, etc. Each species therefore has unique environmentalrequirements for the maintenance of its life cycle.Most female mosquitoes have to feed on an animal and get a sufficient blood meal before shecan develop eggs. If they do not get this blood meal, then they will die without laying viableeggs. However, some species of mosquitoes have developed the means to lay viable eggs withoutgetting a blood meal.The length of life of the adult mosquito usually depends on several factors: temperature,humidity, sex of the mosquito and time of year. Most males live a very short time, about a week;and females live about a month depending on the above factors. Mosquito Life Cycle
  3. 3. The mosquito goes through four separate and distinct stages of its life cycle and they are asfollows: Egg, Larva, pupa, and adult. Each of these stages can be easily recognized by theirspecial appearance. There are three common groups of mosquitoes living in the Bay Area.They are Aedes, Anopheles and Culex . Aedes transmit yellow fever, Anopheles transmit malariaand filariasis and Culex transmit filariasis.Eggs are laid one at a time and its depend to the type of genera of mosquito Culex, andAnopheles lay their eggs on water while Aedes lay their eggs on damp soil that will be flooded bywater. Most eggs hatch into larvae within 48 hours.Larva : The larva live in the water and come to the surface to breathe. The larva feed on micro-organisms and organic matter in the water. On the fourth molt the larva changes into a pupa.Pupa: The pupal stage is a resting, non-feeding stage. This is the time the mosquito turns into anadult. It takes about two days before the adult is fully developed. When development iscomplete, the pupal skin splits and the mosquito emerges as an adult.Adult: The newly emerged adult rests on the surface of the water for a short time to allow itselfto dry and all its parts to harden. Also, the wings have to spread out and dry properly before itcan fly.LIFE CYCLE OF COCKROACHCockroach are organism who are attracted to human excreta in the latrines where as they findmoisture and food for there survival and growth. They eats both food and faeces of human beingand domestic animals. By feeding on infected faeces and later on food cockroach contaminatethe food and hence transmit diseases.The cockroach undergo four stages which is egg, nymph one and two then the adult one.
  4. 4. They prefer to live in close association with there food and in dark place in order to obtain waterand food. In most time cockroach move from sewers into homes and carries faeces on theirbodies,legs or in their gut.They transmit typhoid bacteria, cholera, dysentery and enteric virus.The best way of there control is by protection of food and an emproved domestic sanitation.
  5. 5. LIFE CYCLE OF LICEHead lice are insects that feed off the of the blood of their host. One louse can produce hundredsof eggs during its lifespan. Head lice live for nearly two months and have three stages of life. Amature or adult head louse can lay up to 10 eggs or nits each day. These nits, or lice eggs, hatchin about 7 to 12 days. Baby lice or nymphs are about the size of a pinhead when they hatch, andquickly mature into adult lice in about 9 to 12 days. In just a few days, adult lice are readymate, starting this lice life cycle all over again during their 3 to 4 week lifespan.Nits are laid by female lice at the base of the hair shaft. Once laid, nits take five to 10 days tohatch. Eggs, which are about the size of sesame seeds, are yellowish-brown to white in color.When the nits hatch, they release nymphs.Nymphs look like adult lice, but are smaller in size. Nymphs molt (outgrow their exoskeleton)three times before becoming an adult. The nymph stage lasts up to seven days.The adult is the third stage of head lice. Adults can live up to 30 days and feed off the host up tofive times a day. Adult females will lay up to a dozen eggs a day.
  6. 6. Lice are often transmitted from host to host via objects that come in contact with hair. Head licecan go two or three days without feeding and can live on detached hair strands, clothing, hats,combs, towels and bedding.
  7. 7. LIFE CYCLE OF ASCARIS LUMBRICOIDESAre also known as round worms of man. Is the largest of the intestinal nematodes parasitizinghumans. It is the most common worm found in human. It is worldwide in distribution and mostprevalent through out the tropics, sub-tropics and more prevalent in the countryside than in the city.The adults are cylindrical in shape, creamy-white and pinkish in color. The female averages20~35cm in length, the largest 49cm. The male is smaller, averaging 15~31cm in length anddistinctly more slender than the female. The typical curled tail with a pair sickle like copulatoryspine readily distinguishes males. On the tip of the head there are three lips, arranged as a Chineseword “ 品 ”. They have a complete digestive tract. Reproductive organs are tubular. male has asingle reproductive tubule. The female has two reproductive tubules and the vulva is ventrallylocated at the posterior part of the anterior 1/3 of the body. There are three kind of the eggs. Theyare fertilized eggs, unfertilized eggs and decorticated eggs. We usually describe a egg in 5 aspects:size, color, shape, shell and content. Fertilized eggs: broad oval in shape, brown in color, an average size 60 x45µm . The shell isthicker and consists of ascaroside, chitinous layer, fertilizing membrane and mammillatedalbuminous coat. The content is a fertilized ovum. There is a new-moon shaped space at the eachend inside the shell.Unfertilized egg: Longer and slender than a fertilized egg. The chitinous layer and albuminous coatare thinner than those of the fertilized eggs without ascaroside and fertilizing membrane. Thecontent is made of many refractable granules various in size.Decorticated eggs: Both fertilized and unfertilized eggs sometimes may lack their outer albuminouscoats and are colorless. . Life Cycle 1. Site of inhabitation: small intestine 2. Infetive stage: embryonated eggs 3. Route of infection: by mouth
  8. 8. 4. No intermediate and reservoir hosts 5. Life span of the adult: about 1 yearLIFE CYCLE OF HOOKWORMSHookworm is the second most common human helminthic infection (after ascariasis).Hookworm species are worldwide in distribution, mostly in areas with moist, warmclimate. Infection of the host is by the larvae, not the eggs. While a duodenal can be ingested, theusual method of infection is through the skin; this is commonly caused by walking barefootthrough areas contaminated with fecal matter. The larvae are able to penetrate the skin of thefoot, and once inside the body, they migrate through the vascular system to the lungs, and fromthere up the trachea, and are swallowed. They then pass down the esophagus and enter thedigestive system, finishing their journey in the intestine, where the larvae mature into adultworms The cycleOnce in the host gut, Necator tends to cause a prolonged infection, generally 1–5 years (manydie within a year or two of infecting), though some adult worms have been recorded to live for15 years or more. On the other hand, Ancylostoma adults are short lived, surviving on averagefor only about 6 months. However, infection can be prolonged because dormant larvae can be"recruited" sequentially from tissue "stores" (see Pathology, above) over many years, to replace
  9. 9. expired adult worms. This can give rise to seasonal fluctuations in infection prevalence andintensity (apart from normal seasonal variations in transmission).LIFE CYCLE OF RATRats are born in a nest, in a litter of 6-8 young. The nest is often in a secure place with nestingdebris such as in an attic in the insulation. They are born tiny and hairless (pinkies), with eyessealed shut. After two weeks of nursing, their eyes open, and within 4 weeks, they are weaned.After three months of life, they are independent and on their own, although they typically use thesame habitat as their birthplace (i.e. they live in the same home or attic).Small rats after bornRats dont live particularly long in the wild. Like all rodents, they rely upon breeding in highnumbers and eating a lot and growing quickly. In this respect, they are somewhat like insects,and thus can sometimes swell to large numbers given the right conditions. In normalcircumstances, disease and predators keep their numbers in check. Rarely do rats live for morethan a year in the wild. During that year, however, they can create a lot of new rats and aRats dont live particularly long in the wild. Like all rodents, they rely upon breeding in highnumbers and eating a lot and growing quickly. In this respect, they are somewhat like insects,and thus can sometimes swell to large numbers given the right conditions. In normalcircumstances, disease and predators keep their numbers in check. Rarely do rats live for morethan a year in the wild. During that year, however, they can create a lot of new rats and a lot ofdamage. Just one adult female can create more than 40 new rats in a year. In their lifetime, rats
  10. 10. tend to stick to familiar territory.They are not explorers. They find an area that suits their needs, with shelter and food (humanhomes and attics quite often fit the bill) and rarely venture more than a few hundred feet fromthat area. They rarely die naturally, but when they do, its often in safe place like your attic, andyoull notice the smell. Most will be killed by predictors. Cycle of rat.