top of page
BZYET-143: Insect Vectors and Vector Borne Diseases

BZYET-143: Insect Vectors and Vector Borne Diseases

IGNOU Solved Assignment Solution for 2023

If you are looking for BZYET-143 IGNOU Solved Assignment solution for the subject Insect Vectors and Vector Borne Diseases, you have come to the right place. BZYET-143 solution on this page applies to 2023 session students studying in BSCG courses of IGNOU.

Looking to download all solved assignment PDFs for your course together?

BZYET-143 Solved Assignment Solution by Gyaniversity

Assignment Solution

Assignment Code: BZYET-143/TMA/2023

Course Code: BZYET-143

Assignment Name: Insect Vectors and Vector Borne Diseases

Year: 2023

Verification Status: Verified by Professor


Note: Attempt all questions. The marks for each question are indicated against it.




Q1) Which structural, developmental and behaviouristic characteristics make insects highly successful organisms on Earth? (10)

Ans) Insects are among the most diverse and successful groups of organisms on Earth. They have colonized nearly every habitat on the planet, from the oceans to the highest peaks. There are over one million known species of insects, and it is estimated that there may be as many as ten million more yet to be discovered. Insects play important roles in ecosystems, acting as pollinators, decomposers, and as a food source for other animals.


The structural, developmental, and behavioural characteristics that make insects so successful are:


Structural Characteristics: One of the key structural characteristics that have contributed to the success of insects is their exoskeleton. The exoskeleton is a tough, chitinous outer covering that provides protection against predators, physical damage, and dehydration. The exoskeleton also provides structural support for the body, enabling insects to maintain their shape and size even when they are not supported by water. Additionally, the exoskeleton provides a surface for muscle attachment, allowing insects to move and manipulate their environment.


Insects also have a highly efficient respiratory system, which enables them to obtain oxygen directly from the air. Insects breathe through a system of tubes called tracheae, which branch throughout the body and deliver oxygen directly to the cells. This system is much more efficient than the mammalian respiratory system, which requires a circulatory system to transport oxygen to the cells.


Developmental Characteristics: The developmental characteristics of insects have also contributed to their success. Insects have a unique life cycle, consisting of four stages: egg, larva, pupa, and adult. This life cycle allows insects to exploit a wide range of food resources and habitats. For example, the larvae of some insects feed on different foods than the adults, and some larvae are adapted to live in aquatic environments while the adults live on land.


Another key developmental characteristic of insects is their ability to undergo metamorphosis. Metamorphosis is the process by which insects transform from one stage to another, for example, from a larva to a pupa or from a pupa to an adult. During metamorphosis, the insect undergoes a radical restructuring of its body, allowing it to adapt to different environments and food sources. Metamorphosis has enabled insects to colonize a wide range of habitats, including land, water, and air.


Behavioural Characteristics: Insects have also evolved a wide range of behavioural characteristics that have contributed to their success. One of the most important of these is their ability to communicate with each other using pheromones. Pheromones are chemicals that are released by insects and detected by other insects, often for the purpose of mating or marking territories. This communication system allows insects to coordinate their activities and respond to changing environmental conditions.


Insects are also known for their social behaviour, particularly in the case of ants, bees, and termites. Social insects live in large, organized colonies, with individuals performing specialized roles such as worker, queen, or soldier. This social organization allows insects to exploit resources that would be impossible for solitary organisms to access. For example, ants can work together to carry objects much larger than any individual ant could move on its own.


Q2) Write short notes on following: (10)


i) Mouthpart modifications in insects

Ans) Insect mouthparts have become very different over time to meet the needs of different feeding habits. There are many ways for insects to use their mouth parts, such as piercing sucking, chewing, sponging, and lapping.


Insects that eat plant sap, nectar, or blood have mouth parts that can pierce and drain. Most of the time, these mouthparts are long and needle-like, and they are used to pierce the host organism and pull fluids out. Mosquitoes, aphids, and ticks all have mouth parts that can pierce and then feed.


Insects that eat solid food, like leaves, stems, or other insects, have mouth parts that help them chew. The mandibles and maxillae make up these mouth parts. They are used to bite and crush food. Bugs like grasshoppers, beetles, and caterpillars have mouth parts that can chew.

Bugs that eat liquids like fruit juice or plant sap have mouth parts that can soak up liquids. The labella and maxillae make up these mouth parts. They are used to soak up food. Fruit flies and butterflies both have mouth parts that look like sponges.


Insects that eat liquids, like nectar or blood, have mouth parts that overlap. This part of the mouth is a long, thin tube called a proboscis. It is used to lap up food. Moths and butterflies are examples of insects with mouthparts that overlap.


ii) Types of antennae in insects

Ans) Insects' antennae are highly specialised sensory organs that play a key role in how they act and how they stay alive. They help insects learn about their surroundings, find food, find mates, and talk to each other. Insects have many kinds of antennae, and each one is built and works in a different way.


The length and width of a filiform antenna are the same all the way along its length. They are often found on beetles, ants, and other insects that live in the soil or on dead leaves. Filiform antennae are used to find chemicals and vibrations in the environment.


Moniliform antennae look like beads and are made up of several segments. They can be found on aquatic insects like water beetles and dragonflies. Moniliform antennae are used to find prey and sense currents.


Serrate antennae look like saws and have tiny bumps all along their length. They are found in insects like moths and butterflies that eat flowers and other plants. Chemicals in the environment can be found by using antennas with sharp edges.


Lamellate antennae have flattened parts that look like leaves and are used to find chemicals in the air. They can be found in moths, beetles, and bees, among other insects.


The tip of clubbed antennae is thickened and rounded, which makes them look like clubs. They are found in beetles, moths, and butterflies, among other insects. With clubbed antennae, chemicals can be found, and the environment can be sensed.


iii) Typical structure of insect wing

Ans) Insect wings are highly specialised structures that have evolved over time to allow insects to fly. This ability has helped insects thrive and become more diverse on Earth. Even though the shape and size of insect wings vary a lot from one species to the next, they all have the same basic structure.


An insect wing is usually made up of a thin, flat membrane that is held up by a framework of veins. The membrane has two layers of cuticle that are separated by air spaces that help make the wing lighter. The veins, which are also made of cuticle, give the wing its shape and strength. They also let hemolymph, which is like blood in insects, flow through them.


The veins are set up in a branching pattern that is different for each insect species. The main veins, called the costa and subcosta, run along the leading edge of the wing, and the other veins branch out from them. The thin wing membrane fills the space between the veins, which is called the intercostal region.


Taxonomic characters like the shape and arrangement of the veins and the presence or absence of structures like cross veins or nodus are used to put insects into different groups.

iv) Leg modifications in insects

Ans) Insects have changed their legs in many ways to adapt to different environments, ways of life, and behaviours. Because of these changes, they can move, climb, dig, swim, jump, and grab with a high level of accuracy and efficiency.


One of the most common ways that insects change their legs is by adding spines, hooks, or sticky pads to the tarsi, which are the tips of the legs. These structures help insects climb up vertical surfaces and stick to rough or slippery surfaces, like tree trunks, rocks, or smooth leaves. Geckos, spiders, and flies are all examples of insects with sticky pads.


Insects often change their legs so that they are long and thin, which helps them move quickly and efficiently over long distances. For example, grasshoppers, crickets, and spiders all have long legs.

Some insects' legs have been changed to help them swim or dive. These legs may be flattened, fringed, or paddle shaped. They may also be water-repellent or water-attractive, which helps the insect stay on the surface of water or sink. Water striders, backswimmers, and diving beetles are all kinds of insects that can swim or dive with their legs.


Some insects' legs have been changed so that they can dig or burrow. These legs may be thicker or longer than usual, and they may have sharp spines or ridges that help them dig into the ground or other surfaces. Ants, termites, and mole crickets are all examples of insects with legs that can dig or burrow.


Q3i) Read the following sentences and tick mark the correct alternative. (4)


a) Incubating/Convalescent carriers are infected and can spread the pathogen, but do not show the symptoms of illness.

Ans) Convalescent carriers are infected and can spread the pathogen, but do not show the symptoms of illness.


b) The only function of mechanical/biological vectors is to transport the infectious agents which don’t really need vectors to complete their life cycle.

Ans) The only function of mechanical vectors is to transport the infectious agents which don’t really need vectors to complete their life cycle.


c) In propagative/cyclopropagative transmission the pathogen undergoes a developmental cycle and multiplication in the body of arthropod.

Ans) In propagative transmission the pathogen undergoes a developmental cycle and multiplication in the body of arthropod.


d) Some virus and rickettsia are transmitted from male/female parent through the sperms/eggs to the offspring.

Ans) Some virus and rickettsia are transmitted from female parent through the eggs to the offspring.

Q3ii) Differentiate between: (6)

Q4i) Name four insect orders which are of medical importance. Write at least one conspicuous feature and three examples of each order. (4)

Ans) There are several orders of insects that are important to medicine because they can spread diseases to people and animals. Diptera, Hemiptera, Siphonaptera, and Anoplura are four orders of insects.

  1. Diptera: Diptera are easy to spot because they have two wings that they use to fly and small knobs on their bodies called halteres that help them keep their balance in the air. Mosquitoes (Anopheles, Aedes, and Culex), sand flies (Phlebotomus and Lutzomyia), and black flies are all types of insects (Simulium).

  2. Hemiptera: Hemipterans are often called "true bugs" and have piercing-sucking mouth parts that they use to get fluids from plants or animals. Bed bugs (Cimex lectularius), kissing bugs (Triatoma), and assassin bugs (Cimex niger) are a few examples (Reduviidae).

  3. Siphonaptera: Fleas, which are Siphonapterans, stand out because their bodies are flattened so they can move through the fur or feathers of their hosts. Cat flea (Ctenocephalides felis), dog flea (Ctenocephalides canis), and human flea (Ctenocephalides scapularis) (Pulex irritans).

  4. Anoplura: Anoplurans, which are commonly called "lice," stand out because their bodies are flattened, and their wings are short. They are also obligate ectoparasites that live on the skin or feathers of their hosts.


Human body louse (Pediculus humanus humanus), human head louse (Pediculus humanus capitis), and crab louse are all kinds of louses that can live on humans (Pthirus pubis).  Diseases like malaria, dengue fever, Chagas disease, Lyme disease, plague, and typhus fever have all been linked to these insect orders. Understanding how these insects live and act is important for coming up with effective ways to control them and stop the spread of disease.


Q4ii) Give reasons for the following features found in insects. (6)

a) Fleas have a laterally compressed body.

Ans) Fleas have bodies that are flattened from side to side, which is called "lateral compression." The shape of their bodies is unique because they have evolved to live and move through the fur or feathers of their hosts.


There are several reasons why fleas have a body that is shorter on one side than the other:

  1. Efficient Movement: Fleas can move quickly through the thick hair or feathers of their hosts because their bodies are flat. It helps them get around in the fur and feathers without getting stuck or tangled up. Fleas need to be able to move quickly so they can find new hosts and avoid getting eaten.

  2. Concealment: Fleas can hide in the fur or feathers of their hosts because of the way their bodies are shaped. This helps them blend in with their surroundings, making it harder for their host to find them and get rid of them.

  3. Blood feeding: Fleas are obligate ectoparasites, which means that they must feed on the blood of their hosts to stay alive. Fleas can get into the skin of their hosts and feed on their blood with their piercing-sucking mouthparts because their bodies are narrower on the side. This shape also keeps them from being seen by the host while they are feeding.


b) Forewings of a few hemipterans are called hemelytra.

Ans) Hemelytra are the modified forewings of some hemipterans that have a hardened base and a soft tip. Hemelytra are an important part of the suborder Heteroptera, which includes many important insects for medicine, such as assassin bugs, kissing bugs, and bed bugs.

There are a few important things about hemelytra:

  1. Flight: The insect can fly because the end of the hemelytra is made of a membrane. The wings give the insect lift and help it move, while the hemelytra help it stay still and move in the right direction.

  2. Thermoregulation: The hemelytra also help control the temperature. The hard part at the bottom of the hemelytra helps to keep heat in and keep the body temperature stable. The soft part at the top of the hemelytra allows heat and moisture to be exchanged with the environment.

  3. Communication: Some hemipterans talk to other members of their species by moving their hemelytra. For example, bed bugs use their hemelytra to make a smell that helps them find potential hosts and attracts other bed bugs.


c) Hind legs of fleas are saltatorial types with large coxae.

Ans) Fleas are wingless, jumping bugs. Their jumping back legs help them escape danger. Saltatorial back legs help fleas leap. Fleas' hip joints, called coxae, are large and robust. This supports their strong jumping muscles. Back leg tibias and tarsi form the tarsus-tibia. The flea's tarsus-tibia helps it store and use energy while jumping.


Fleas have jump-ready legs. The flea can jump 200 times its length, like a person jumping over a big skyscraper. When a flea jumps, its large coxae and strong muscles generate a lot of force, and its unusual tarsus-tibia enables it store and release energy. Fleas can jump and move through hair and feathers using their legs. Fleas' lengthy legs and large coxae allow them to pass through fur and feathers. Their sharp tarsus-tibia claws attach to their host.


d) Saliva of hematophagous insects contain anticoagulant.

Ans) Mosquitoes, ticks, fleas, and bed bugs feed on vertebrate blood. These insects generate saliva anticoagulants to eat blood. Haematophagous insects' saliva contains several anti-clotting proteins and enzymes. Thrombin inhibitor enzyme is crucial to insect saliva. This enzyme blocks blood clotting protein thrombin.


Besides thrombin inhibitor, haematophagous insects produce anticoagulants such hirudin and apyrase to prevent blood clotting and make eating simpler. Anticoagulants enlarge blood arteries and prevent platelets from sticking together to keep blood moving.  Haematophagous insects need salivary anticoagulants to feed on blood without being detected by their host's immune system. Anticoagulants can prolong bleeding and increase infection risk in the host.


e) Heteroptera have a characteristic scutellum which is absent in homopterans.

Ans) Hemiptera includes Heteroptera and Homoptera. Hemipterans are "real bugs." Crop loss and disease transmission make them essential to the economy. Heteroptera and Homoptera appear and behave differently. The scutellum, a shield-like structure on the back of the thorax, differs.


Heteroptera contains numerous genuine bugs. These bugs have a triangular or shield-shaped scutellum that covers the mesothorax and portion of the metathorax. The scutellum helps identify Heteropterans by family. The scutellum covers the wings and body and helps the bird fly. The scutellum releases fragrance and defence compounds.


Homoptera lacks a scutellum. The back is plain, and the thorax is flat or slightly rounded. Most Homopterans have smaller wings than Heteropterans. Homopterans evolved without scutellums to suit their lives and ecological niches. Homopterans dwell in water and land and eat many different foods. Their keen, sucking mouthparts help them feed on plant sap. Heteropterans have a larger diet.


f) The under surface of the housefly labella has prestomial teeth.

Ans) At the end of a housefly's proboscis, there are two fleshy structures called labella. They help flies taste food and move it around. Houseflies have special structures called prestomial teeth on the underside of their labella. On the underside of the labella, these teeth are small chitinous structures that are arranged in a comb-like pattern. People think that the fly's prostomial teeth help it eat many kinds of food.


They can pierce and hold soft or semi-solid foods like fruits or dead animals, and they can also scrape and drink liquids like nectar or blood. The teeth may also help us sense and understand how different foods taste and feel. Houseflies are not the only insects with premolar teeth. Blowflies and fruit flies, which are related, also have similar structures. But the size and arrangement of the teeth can be different between species, which may be a result of how they eat.


Q5i) Explain the role of Reduviid bug as a biological vector in the transmission of Chagas disease. (5)

Ans) The protozoan parasite Trypanosoma cruzi causes Chagas disease, which is also called American trypanosomiasis. People get the disease from the bites of infected triatomine bugs, also called kissing bugs or assassin bugs, which are common in South and Central America. One of the most important biological carriers of Chagas disease is the Reduviid bug (Triatoma infestans).

Reduviid bugs are bloodsucking bugs that are often found in poor, rural areas of South and Central America.


Most of the time, these bugs feed at night on the blood of mammals, including people. When they bite, they inject their saliva into the host's skin. This saliva contains anticoagulants and enzymes that break down the host's tissue and make it easier for the bug to feed. During feeding, if the bug is infected with T. cruzi, the parasite can be passed to the host.

Once the T. cruzi parasite is inside its host, it can multiply and spread to different organs, causing fever, fatigue, muscle aches, and swollen lymph nodes, among other symptoms.


In some cases, the infection can cause heart and stomach problems that last for a long time and can be fatal. There are several reasons why reduviid bugs are good biological carriers of Chagas disease. First, they are very well-suited to eating human blood, and their mouths are made to break through the skin and get to the blood vessels. Second, they eat at night, so they are more likely to meet people who are sleeping. Third, they can poop while they are eating, which can make it more likely that T. cruzi will spread. Lastly, they can live for a long time without eating. This means that they can stay infected with T. cruzi for a long time, which makes it more likely that it will spread to new hosts.


Chagas disease can be prevented and controlled by making it less likely that people will meet infected reduviid bugs. This can be done in several ways, such as by making homes safer, spraying them with insecticide, and using bed nets. Also, early diagnosis and treatment of people who are infected can help stop the disease from spreading and stop it from getting worse.


Q5ii) What preventive measures will you take for controlling the bed bugs from entering your house? (5)

Ans) Bed bugs are parasitic insects that feed on the blood of people and animals. People have seen them in homes, hotels, and other buildings. Their bites can cause skin irritation, allergies, and other health problems. The best way to stop bed bugs from coming into your home is to take steps to keep them out.


Here are some things you can do:

  1. Keep Your Home Clean: The first step to keeping bed bugs away is to clean your home often. You should regularly vacuum your carpets, floors, and furniture, and wash your clothes and bed sheets in hot water.

  2. Seal Cracks and Crevices: Bed bugs can get into your home through cracks and crevices, so seal any holes in the walls, floors, and ceilings. This will also stop other bugs from getting into your house.

  3. Use Bed Bug-proof Encasements: Use encasements that keep bed bugs out: Put your mattress, box spring, and pillows in covers that will keep bed bugs out. Bed bugs will not be able to get in and hide in these places.

  4. Reduce Clutter: Bed bugs can hide in messes, so try to keep your home as clean as possible. Don't leave clothes, papers, or other things piled up.

  5. Inspect second-hand items: Before bringing used furniture or clothes into your home, check them carefully for signs of bed bugs.

  6. Use a Bed Bug Detector: Bed bug detectors can help you find out if your home has bed bugs. Bed bugs are attracted to CO2, so these detectors can help you find where bed bugs are hiding.


Hire a professional pest control service: If you think you might have bed bugs in your home, it's best to call a pest control service. They will be able to figure out how bad the bed bug problem is and take the right steps to get rid of the bugs.





6i) Read the following sentences and write True (T) or False (F). (6)


a) Malaria is a disease caused by Anopheles mosquito.

Ans) False.


b) The vector for malaria is Culex species.

Ans) False.


c) The infection of malaria starts when a female mosquito injects sporozoites of Plasmodium sp. present in her saliva into a human skin.

Ans) False.


d) Plasmodium cannot complete its life cycle at temperature below 20oC.

Ans) False.


e) During pregnancy malaria can lead to premature baby delivery.

Ans) Ture.


f) Most malarial deaths occur in urban areas.

Ans) False.


ii) Discuss the preventive and control measures of Anopheles mosquito. (4)

Ans) Preventive and control measures for Anopheles mosquito include both personal and environmental interventions.


Personal Interventions

  1. Use of Mosquito Nets: One of the best ways to stop malaria is to sleep under a long-lasting insecticidal net (LLIN) or an insecticide-treated bed net (ITN).

  2. Use Insect Repellents: DEET, Picaridin, and IR3535 are some of the best insect repellents that you can put on your skin or clothes to keep mosquitoes from biting you.

  3. Putting on Protective Clothing: Long-sleeved shirts and pants can help keep mosquito bites away from the skin.

  4. Limit Your Time Outside: You're less likely to get bitten if you don't do things outside at dusk or dawn, when mosquitoes are most active.


Environmental interventions

  1. Source Reduction: Reduce the number of mosquito breeding sites by getting rid of standing water around homes and communities.

  2. Larvicides: Larvicides can kill mosquito larvae in still water sources like ponds, ditches, and swamps before they turn into adults.

  3. Spraying Insecticides: Indoor residual spraying (IRS) with insecticides like pyrethroids can kill mosquitoes that get into homes and stop the spread of malaria.

  4. Biological Control: Putting mosquito predators like fish that eat mosquito larvae and copepods in water can help control the number of mosquito larvae.

  5. Genetic Modification: Making mosquitoes with genes that kill them or that make them resistant to malaria can help reduce the number of mosquitoes.


When these steps are taken together, they can help prevent and control the Anopheles mosquito and, in the long run, stop it from spreading malaria.


Q7i) Write a short note on dengue prevention and control. (4)

Ans) Dengue is a disease caused by a virus that is spread to people by the bite of an infected Aedes mosquito, especially an Aedes aegypti mosquito. It is common in tropical and subtropical parts of the world, and its symptoms include high fever, severe headaches, pain in the joints and muscles, and a rash.


Dengue can be stopped and kept under control by:

  1. Eliminating Mosquito-Breeding Areas: Aedes mosquitoes lay their eggs in still water, so it's important to get rid of anything that can hold water, like flower vases, old tyres, or other containers. This can be done by keeping the place clean and taking care of trash the right way.

  2. Using Insect Repellents: Putting DEET-based mosquito repellents on your skin and clothes can help keep mosquitoes from biting you.

  3. Wearing Protective Clothing: Long-sleeved shirts and pants that cover exposed skin can make it less likely that mosquitoes will bite you.

  4. Use of Mosquito Nets: Sleeping under an insecticide-treated mosquito net can help keep mosquito bites from happening.

  5. Community-based Interventions: Controlling dengue is impossible without the help of the community. Programs to teach people about mosquitoes and regular clean-ups can help get rid of places where they can breed.

  6. Vector Control: Insecticides and larvicides can be used to control the number of mosquitoes. Adult mosquitoes can also be taken care of by fogging and spraying.


Q7ii) Draw a labelled diagram of: (6)



Q8) Write short notes on: (10)


a) Traps used for controlling houseflies

Ans) Houseflies are one of the most common pests that can be found in homes, businesses, and the outdoors. They are known to spread diseases like typhoid, cholera, and dysentery, which makes it important to keep their numbers in check. Putting out traps is one way to get rid of houseflies.

There are different kinds of traps used to get rid of houseflies, such as:

  1. Sticky Traps: These traps have a sticky substance on them that attracts flies and stops them from moving. They are usually put where houseflies are most likely to be, like near garbage cans or places where food is stored. Sticky traps are easy to set up and throw away, but you need to replace them often.

  2. Light Traps: UV light is used to draw flies to these traps, which then trap them inside. Most of the time, they are used in places like restaurants and supermarkets where there are a lot of houseflies. Fly numbers can be cut down with light traps, but they can be expensive to keep up.

  3. Bait Traps: Flies are drawn to these traps with a mixture of sugar and water. Once the flies get inside, they can't get out. Most of the time, they are used outside, in places like gardens or barns. Bait traps are easy to set up and don't cost much money, but they need to be put in places where there are a lot of houseflies.

  4. Electronic Traps: Flies that touch the electric grid inside these traps will die. They are usually used in places like restaurants and hospitals where there is a need to get rid of flies quickly and effectively. Electronic traps are expensive to buy and keep up, but they do a good job of catching and killing flies.


b) Cultural control of Musca

Ans) Cultural control is the practise of stopping housefly (Musca domestica) infestations by doing things that make it hard for them to breed and eat. Some cultural control measures for Musca are:

  1. Sanitation: Houseflies have less places to live and eat when organic waste, garbage, and animal waste are thrown away in the right way. This means covering trash cans, cleaning up dropped food, and taking out animal waste and animal bedding on a regular basis.

  2. Exclusion: Houseflies can't get into buildings if doors, windows, and vents are sealed up. Screens, weather stripping, and door sweeps can all be used to do this.

  3. Changing the Environment: Lessening the number of wet areas and organic matter around buildings can keep houseflies from living there. This can be done by fixing leaks, using fans to move the air around, and cleaning the gutters.

  4. Biological Control: Predators and parasitoids that live in nature can be used to keep houseflies in check. Wasps like Spalangia endius and Muscidifurax zaraptor, which are parasitic, are known to eat the pupae of houseflies.

  5. Trapping: Houseflies can be caught and killed with sticky fly paper, fly strips, and electronic traps. Adult flies can also be caught and killed with the help of UV light traps.

  6. Chemical Control: Insecticides can be used to kill adult flies or treat places where they breed. But care should be taken to use them according to the directions on the label and to keep the environment clean and not hurt organisms that aren't the target.


c) Chemical control of housefly

Ans) For chemical control of houseflies, insecticides are used to kill or scare away adult flies or stop fly larvae from growing. These are some of the most common chemical ways to get rid of houseflies:

  1. Sprays: Aerosol or long-lasting sprays can be used in places where houseflies tend to rest or lay their eggs. These sprays have insecticides in them that kill flies as soon as they touch them.

  2. Baits: Adult flies can be caught and killed with fly baits. Most of the time, these baits have a toxic insecticide mixed with sugar or protein. The bait draws flies, which eat it and then die within a few hours.

  3. Larvicides: Garbage cans, compost piles, and manure heaps can all be used to kill fly larvae by putting chemicals on them. With these larvicides, fly larvae will not grow up into adult flies.

  4. Residual Treatments: Insecticides that stay in place can be put on surfaces like walls, floors, and ceilings where flies tend to rest. These insecticides can kill flies for up to a few weeks if they meet them.


It's important to carefully follow the instructions on the insecticide's label and use it in line with the rules in your area. Too much use of insecticides can make insects resistant to them, and some of them may be harmful to organisms other than the ones they are meant to kill.

Integrated pest management (IPM) strategies, which use more than one way to get rid of pests, can help reduce the number of houseflies while using less insecticide. This could include things like making sure the area is clean and changing the way it looks, as well as biological methods like using natural enemies like parasitic wasps.


d) Myiasis

Ans) Myiasis is a parasitic infestation caused by the larvae of dipterous insects that feed on living or dead tissue or body fluids of vertebrate animals, including humans. The fly larvae feed on the host tissue, causing tissue damage, pain, and infection. The infestation can occur in various body parts, including the skin, eyes, nose, ears, mouth, and gastrointestinal tract.


There are different types of myiasis based on the location of infestation, including cutaneous myiasis, ophthalmic myiasis, nasopharyngeal myiasis, aural myiasis, and gastrointestinal myiasis. The symptoms of myiasis vary depending on the type and location of infestation. Some common symptoms include itching, pain, swelling, inflammation, and discharge.


The prevention and control of myiasis involve different measures depending on the location of the infestation. For cutaneous myiasis, personal hygiene, proper wound care, and covering the wound with a clean dressing can prevent the infestation. Insect repellents can also be used to prevent fly infestation.

For the prevention and control of gastrointestinal myiasis, proper disposal of feces and management of animal waste can reduce the breeding sites for flies. Food should be covered and stored properly, and garbage should be disposed of properly. Insecticides can be used to control fly infestations in certain circumstances, such as in animal husbandry and agricultural settings. However, the use of insecticides should be done with caution to avoid harm to human health and the environment.


Q9i) Write the ecological factors favourable for the transmission of Kala-azar. (4)

Ans) Visceral Leishmaniasis, which is another name for Kala-azar, is a parasitic disease that is spread to people by the bite of an infected female Phlebotomus sandfly.


Several environmental factors play a role in how Kala-azar spreads:

  1. High population Density of Sandflies: Kala-azar is more likely to spread in places where there are a lot of sandflies. This is because the chance that an infected sandfly will bite a person goes up as the number of sandflies goes up.

  2. High Humidity and Temperature: Sandflies like places that are warm and have a lot of moisture in the air. When the temperature and humidity are high, sandfly populations grow, and Kala-azar is more likely to spread.

  3. Deforestation: Sandflies and Kala-azar may spread because of deforestation and other changes in how land is used. This is because when trees are cut down, people are more likely to meet sandflies and the ecological balance can change in ways that help sandflies grow.

  4. Poverty: Kala-azar can spread more easily in places where people are poor and don't have good housing or sanitation. Poor living conditions also make people more likely to be malnourished and have weaker immune systems, which makes them more likely to get sick.

  5. Reservoir Hosts: It has been found that domestic dogs are important sources of Kala-azar. The risk of transmission is higher in places where there are a lot of infected dogs, especially if they live close to people.


Q9ii) Illustrate the transmission of visceral leishmaniasis in human beings. (6)

Ans) The protozoan Leishmania donovani is the causative agent of the parasitic disease known as visceral leishmaniasis. It is also known by the name Kala-azar. The bite of a female phlebotomine sandfly belonging to the genus Phlebotomus is responsible for the transmission of the disease in the Old World. Sandflies of the genus Lutzomyia, namely the females, are responsible for the transmission of the disease in the New World. The disease known as visceral leishmaniasis can be passed on from human to human as well as from animal to animal.


Sandflies are responsible for the transmission of visceral leishmaniasis when they feed on the blood of diseased animals or humans. Along with the blood feast, the parasites that cause leishmania are also consumed. After a few days have passed, the parasites will have grown and multiplied inside of the sandfly's midgut and will be ready to feed. When the infected sandfly feeds on blood a second time, the parasites have the opportunity to be transferred to a new host.


Macrophages are white blood cells that play an important role in the immune system. When a person is infected with Leishmania, the parasites that cause the disease enter the circulation and are consumed by macrophages. After that, the parasites can reproduce and spread throughout the body, which can result in a number of symptoms such as fever, weight loss, spleen and liver enlargement, and anaemia.


There are a number of environmental elements that can contribute to the spread of visceral leishmaniasis. The majority of occurrences of the condition are found in rural areas, which are characterised by high rates of poverty, substandard housing, and a lack of access to medical care. The disease is also more prevalent in areas with a high population density of both humans and animals, particularly dogs, who serve as a potential reservoir for the parasites that cause the disease.


Temperature and humidity can affect how long sandflies live as well as how they behave. Deforestation and other changes to the natural environment can also change the location of sandfly breeding sites, which can further contribute to the spread of visceral leishmaniasis. These are some of the other factors that can influence the transmission of visceral leishmaniasis. There are a number of methods available for preventing and managing visceral leishmaniasis.


Among these include limiting the amount of time that people spend in close proximity to infected sandflies and streamlining the diagnostic and treatment processes for those who do contract the disease. Sandfly populations can be managed through the use of insecticide-treated bed nets and other personal precautions, as well as through the spraying of insecticides indoors in a manner that allows them to remain there for an extended period of time. In addition, programmes that work on lowering the number of sick dogs and other animal hosts may be able to halt the progression of the disease and put a stop to its further spread.


Q10i) Explain the concept of Integrated Vector Management. (5)

Ans) Integrated Vector Management (IVM) is a way to control diseases that are spread by vectors. It focuses on using many different strategies and tools to control vectors and stop the spread of diseases. The goal of IVM is to reduce the number of vectors and the spread of diseases in a way that is good for the environment and doesn't cost too much. To control vector populations, the approach uses a mix of interventions, which may include biological, chemical, physical, and environmental steps.


IVM is made up of five main parts:

  1. Advocacy, organising the public, and passing laws: This part is about letting people know how important vector-borne diseases are and how important it is to have integrated vector management. It also includes producing rules and policies to help put IVM strategies into action.

  2. Collaboration and coordination: IVM require collaboration and coordination between many different sectors and stakeholders, such as public health, agriculture, the environment, and education.

  3. Integrated vector control: This part of the plan involves using a mix of biological, chemical, and physical methods to control vectors. The best way to stop a disease depends on the type of vector, how the disease spreads, and the local environment.

  4. Capacity building: This part involves training and building up the skills of people who control vectors, people who work in health care, and communities, so that IVM strategies can be used effectively.

  5. Monitoring and evaluating: This part involves keeping an eye on the number of vectors, how often diseases happen, and how well control measures are working.


The IVM approach is flexible and adaptable, and the choice of interventions is based on the specific disease and vector ecology, local resources, and the social, cultural, and economic context of the affected communities. The IVM approach is based on the idea that diseases spread by vectors are complicated and have many different parts. To control them in a way that is both effective and long-lasting, you need a broad and multidisciplinary approach.


IVM is good because it encourages people to use more than just chemicals to control vector populations. This is one of its strong points. This method makes it less likely that resistance will develop and has less of an effect on the environment and organisms that are not the target. IVM also focuses on getting the community involved and involved, which can help control efforts last longer and be more successful.


10ii) Why have insects vectors developed resistance to insecticides? (5)

Ans) Insects can become resistant to insecticides when their genes or bodies change in ways that make them immune or tolerant to the effects of insecticides. Malaria, dengue, and Zika are all diseases that are spread by insects, and resistance is a big problem when it comes to stopping them. In many countries, insecticide resistance has become a major problem.


There are a number of reasons why insect vectors have become resistant to insecticides:

  1. Too much Use of Pesticides: One of the main reasons why bugs become resistant is that insecticides are used too much. When insecticides are used often and in large amounts, the insects that live become immune to them. Too much use of insecticides can also cause populations to become resistant.

  2. Poor Application Techniques: How you use an insecticide makes a difference in how well it works. Poor application methods, like using the wrong concentration or not covering all of the target areas, can help resistance grow. If there is not enough coverage, some insects may not be exposed to the insecticide. This could let them live and breed.

  3. Genetic Selection: Insects have a high rate of reproduction, so through natural selection, their populations can change quickly. Some insects may have genes that make them resistant to insecticides if they are exposed to them. These people are more likely to live and have children, so their genes for resistance will be passed on to the next generation.

  4. Cross-Resistance: Insects can become immune to more than one type of insecticide. This is called "cross-resistance," and it happens when resistance mechanisms from different classes of insecticides are used by the same insect. Cross-resistance can happen when different insecticides work in ways that are like each other.

  5. Evolutionary Pressure: When insecticides are used, they put pressure on the insects they are meant to kill, forcing them to evolve resistance so they can stay alive. This is a natural result of the way the insecticides cause natural selection to happen.

100% Verified solved assignments from ₹ 40  written in our own words so that you get the best marks!
Learn More

Don't have time to write your assignment neatly? Get it written by experts and get free home delivery

Learn More

Get Guidebooks and Help books to pass your exams easily. Get home delivery or download instantly!

Learn More

Download IGNOU's official study material combined into a single PDF file absolutely free!

Learn More

Download latest Assignment Question Papers for free in PDF format at the click of a button!

Learn More

Download Previous year Question Papers for reference and Exam Preparation for free!

Learn More

Download Premium PDF

Assignment Question Papers

Which Year / Session to Write?

Get Handwritten Assignments

bottom of page