Arthropods as Parasites and Vectors
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Questions and Answers

Which of the following is an example of a permanently parasitic arthropod?

  • Melophagus ovinus (correct)
  • Culicoides midge
  • Rhipicephalus (Boophilus) microplus
  • Dermanyssus gallinae
  • What is true about the life cycle of the poultry red mite?

  • Adults spend most time on avian hosts
  • They reproduce through cocoon formation
  • Larvae and nymphs often attack birds for blood at night (correct)
  • They feed during the day and hide at night
  • How do mange mites reproduce?

  • Females produce larvae that adhere to their hosts (correct)
  • By producing eggs that fall into the environment
  • By splitting into smaller parasitic units
  • Adults pupate before laying eggs
  • What distinguishes ectoparasites from endoparasites?

    <p>Ectoparasites live on the surface of their hosts (A)</p> Signup and view all the answers

    What is a characteristic feature of the sheep ked, Melophagus ovinus?

    <p>They are wingless and have flattened bodies (D)</p> Signup and view all the answers

    Which characteristic allows some mites to be classified as temporarily parasitic?

    <p>They only visit hosts for a blood meal (C)</p> Signup and view all the answers

    What feature enhances the survival of adult arthropod parasites against predation?

    <p>Strong legs and claws for attachment (B)</p> Signup and view all the answers

    What type of metamorphosis do house flies undergo?

    <p>Complete metamorphosis (C)</p> Signup and view all the answers

    How many larval stages are present in the life cycle of house flies?

    <p>Three (A)</p> Signup and view all the answers

    What is a key characteristic of the feeding method of adult fleas?

    <p>Sponging mouthparts (D)</p> Signup and view all the answers

    What are the stages of the life cycle in arachnids typically classified as?

    <p>Egg, 6-legged larva, 8-legged nymph, 8-legged adult (C)</p> Signup and view all the answers

    What is the primary advantage of arthropod life cycles and reproductive strategies?

    <p>To enhance survival across varying conditions (B)</p> Signup and view all the answers

    What happens to larvae in the three-host tick life cycle after feeding on a host?

    <p>They drop to the ground and moult to nymphs (C)</p> Signup and view all the answers

    Which of the following best describes the condition of larval stages feeding on rotting organic material?

    <p>They are independent and survive on decaying matter (A)</p> Signup and view all the answers

    What is the term used for the stages between larva and adult in complete metamorphosis?

    <p>Pupal stages (A)</p> Signup and view all the answers

    What term is used to describe the juvenile stages of insects that undergo partial metamorphosis?

    <p>Nymphs (A)</p> Signup and view all the answers

    Which of the following characteristics is unique to the Arachnida group of parasites?

    <p>Four pairs of legs (D)</p> Signup and view all the answers

    In insects that undergo complete metamorphosis, what stage typically follows the larval stage?

    <p>Pupa (D)</p> Signup and view all the answers

    How long does it typically take for the life cycle of the human head louse to be completed?

    <p>2 weeks (D)</p> Signup and view all the answers

    What distinguishes the juveniles of insects that undergo complete metamorphosis from adults?

    <p>They have different feeding adaptations (B)</p> Signup and view all the answers

    How do female human head lice secure their eggs?

    <p>By cementing them to hair shafts (C)</p> Signup and view all the answers

    During which stage do insects undergoing partial metamorphosis shed their old cuticle?

    <p>Nymph stage (D)</p> Signup and view all the answers

    Which of the following statements about the life cycle of the cat flea is true?

    <p>Females lay eggs continuously (A)</p> Signup and view all the answers

    What feature of the labella assists in the feeding process of certain parasites?

    <p>They act like a sponge for secretions. (D)</p> Signup and view all the answers

    Which mouthpart structure is specifically adapted for incising the epidermis in blood-feeding parasites?

    <p>Chelicerae (C)</p> Signup and view all the answers

    How do temporary parasites effectively attach and feed from their hosts?

    <p>Through wings and antennae to locate hosts. (B)</p> Signup and view all the answers

    What is the primary role of the hypostome in blood-feeding parasites?

    <p>To form a barbed tube for blood feeding. (A)</p> Signup and view all the answers

    What characteristic helps fleas find their hosts for feeding?

    <p>Their powerful legs for jumping. (B)</p> Signup and view all the answers

    Which mechanism do sponging mouthparts utilize during feeding?

    <p>They spongy absorb blood or secretions. (A)</p> Signup and view all the answers

    What type of parasites utilize the structure of the hypostome during feeding?

    <p>Ticks and mites. (C)</p> Signup and view all the answers

    During which action do the labella with teeth extend for feeding?

    <p>When sponging up fluids. (C)</p> Signup and view all the answers

    What adaptation do fleas have to help them remain on their hosts?

    <p>Flattened bodies to navigate through fur (B)</p> Signup and view all the answers

    What is the survival condition for Sarcoptes scabiei outside of their host?

    <p>They do not survive for more than a few days. (A)</p> Signup and view all the answers

    What defines mechanical transmission by arthropods?

    <p>Pathogens are transferred without involving the vector's life cycle. (C)</p> Signup and view all the answers

    What is required for biological transmission to occur in arthropods?

    <p>Pathogens must move from the gut to the mouthparts. (A)</p> Signup and view all the answers

    In trans-statial biological transmission, how many hosts do ticks typically feed on at different life stages?

    <p>Three hosts at each stage (A)</p> Signup and view all the answers

    What happens to pathogens during the moulting of ticks?

    <p>Pathogens survive the moulting process. (C)</p> Signup and view all the answers

    Which of the following is NOT a factor contributing to biological transmission?

    <p>Transmission through mechanical means (D)</p> Signup and view all the answers

    What characteristic is common among parasites adapted to live on their hosts?

    <p>Adapted body shapes for their niche (A)</p> Signup and view all the answers

    What adaptations do the mouthparts of chewing lice like Columbicola columbae and Trichodectes canis exhibit?

    <p>They possess strong mandibles for chewing skin and hair. (C)</p> Signup and view all the answers

    Which insect is known for having mouthparts adapted for slashing and sponging?

    <p>Tabanid fly (A)</p> Signup and view all the answers

    What functionality do the hypodermic sucking mouthparts of mosquitoes provide?

    <p>They act as proboscis for piercing the skin. (D)</p> Signup and view all the answers

    Which of the following best describes the mouthparts of the stable fly?

    <p>A long proboscis adapted for piercing. (C)</p> Signup and view all the answers

    What is the primary purpose of the cutting and slashing mouthparts seen in midges and tabanids?

    <p>They facilitate the creation of wounds for blood feeding. (C)</p> Signup and view all the answers

    When considering parasitic adaptations for feeding, which type of mouthpart is associated with myiasis fly larvae?

    <p>Curved hooks for tearing tissues. (B)</p> Signup and view all the answers

    Which element of insect mouthparts is primarily responsible for creating a wound during feeding?

    <p>Proboscis (B)</p> Signup and view all the answers

    What type of mouthpart adaptations do Tabinid horses flies possess?

    <p>Cutting and slashing mouthparts. (D)</p> Signup and view all the answers

    What role do nymphs play in the life cycle of insects with partial metamorphosis?

    <p>Nymphs resemble adults and undergo several molts to mature into sexually mature adults.</p> Signup and view all the answers

    How does the life cycle duration of the human head louse influence its transmission among hosts?

    <p>The rapid life cycle, completing in about two weeks, facilitates quick transmission from one host to another.</p> Signup and view all the answers

    What is the significance of female fleas laying eggs continuously in relation to their survival?

    <p>Continuous egg-laying ensures a steady population, increasing the chances of survival and reproduction on their hosts.</p> Signup and view all the answers

    What does complete metamorphosis entail in the life cycle of parasites like the Culex mosquito?

    <p>Complete metamorphosis involves transforming from larvae, which are adapted for feeding, to adults adapted for reproduction.</p> Signup and view all the answers

    In which stage do insects undergoing partial metamorphosis significantly grow in size?

    <p>Insects grow in size significantly during each nymph stage as they molt and mature.</p> Signup and view all the answers

    How does the adaptation of having mouthparts designed for piercing benefit blood-feeding arthropods?

    <p>Piercing mouthparts allow blood-feeding arthropods to access a critical food source for their survival.</p> Signup and view all the answers

    What is the primary advantage of juveniles being adapted for feeding during complete metamorphosis?

    <p>This adaptation allows larvae to grow and accumulate energy reserves vital for their transformation into adults.</p> Signup and view all the answers

    Why is the absence of antennae in arachnids like ticks significant in their classification?

    <p>The lack of antennae distinguishes arachnids from insects and highlights their unique morphological features.</p> Signup and view all the answers

    What are the implications of complete metamorphosis in the life cycle of arthropods?

    <p>Complete metamorphosis allows larvae to exploit different ecological niches than adults, reducing competition for resources.</p> Signup and view all the answers

    How does the life cycle of house flies contribute to their rapid population expansion?

    <p>House flies lay eggs in decaying matter, allowing their larvae to feed on abundant resources, which facilitates rapid reproduction.</p> Signup and view all the answers

    What role does moulting play in the life cycle of arachnids?

    <p>Moulting allows arachnids to transition between life stages, enabling growth and development as they progress from larvae to adults.</p> Signup and view all the answers

    What is the significance of larvae feeding on rotting organic material in arthropod life cycles?

    <p>Feeding on rotting organic material helps larvae to obtain nutrients and recycle organic matter within ecosystems.</p> Signup and view all the answers

    Describe how the three-host tick life cycle maximizes survival and reproduction.

    <p>The three-host tick life cycle allows ticks to feed at different life stages, optimizing nutrient intake from multiple hosts.</p> Signup and view all the answers

    How do the reproductive strategies of arthropod parasites adapt to adverse conditions?

    <p>Arthropod parasites can survive adverse conditions by entering dormant or pupal stages, reducing metabolic needs.</p> Signup and view all the answers

    What is the impact of having multiple larval stages in the life cycle of certain arthropods?

    <p>Having multiple larval stages increases their capacity to exploit various habitats and resource availability.</p> Signup and view all the answers

    Explain the advantages of the partial metamorphosis observed in some arachnids.

    <p>Partial metamorphosis allows arachnids to gradually transition into adults without a pupal stage, enabling quicker adaptation to their environment.</p> Signup and view all the answers

    What structural feature of adult arthropod parasites aids in their protection against desiccation?

    <p>The chitinous exoskeleton helps protect adult arthropod parasites from desiccation.</p> Signup and view all the answers

    Explain how temporary parasites like the poultry red mite utilize their environment for feeding.

    <p>Temporary parasites like poultry red mites spend most of their time away from hosts and attack birds at night to feed on blood.</p> Signup and view all the answers

    Identify a reason why some arthropod parasites adapt to be permanently parasitic.

    <p>Permanent parasitism allows arthropod parasites to exploit a consistent food source and enhance reproductive success.</p> Signup and view all the answers

    How do female sheep keds reproduce in relation to their environment?

    <p>Female sheep keds produce larvae that adhere to wool and pupate immediately, ensuring the young are protected.</p> Signup and view all the answers

    Describe the significance of the life cycle of arthropod parasites in relation to their survival.

    <p>The life cycles of arthropod parasites, which include distinct developmental stages, enhance their adaptability and survival rates.</p> Signup and view all the answers

    What mechanism do arthropod parasites use to evade environmental challenges when off their hosts?

    <p>Ticks can survive off their hosts for extended periods by finding suitable habitats that offer protection from desiccation.</p> Signup and view all the answers

    What role does the lifecycle of Dermanyssus gallinae play in its parasitism strategy?

    <p>The lifecycle of Dermanyssus gallinae includes stages that allow for blood feeding on hosts primarily at night.</p> Signup and view all the answers

    How do adaptations in body structure contribute to the success of female keds as permanent parasites?

    <p>Female keds have strong legs and claws which enable them to cling to their hosts securely while feeding.</p> Signup and view all the answers

    What is the role of maggots in the life cycle of myiasis flies?

    <p>Maggots, or larvae, are parasitic and adapted to feed on living subcutaneous tissue.</p> Signup and view all the answers

    Describe the parasitic nature of Trombicula autumnalis throughout its life stages.

    <p>Trombicula autumnalis is parasitic only as a 6-legged larva, while the nymphs and adults are free-living.</p> Signup and view all the answers

    How do the feeding adaptations of myiasis fly larvae support their survival?

    <p>Myiasis fly larvae have mouthparts adapted for feeding on living tissue, allowing them to gain necessary nutrients.</p> Signup and view all the answers

    What significant adaptation do ticks exhibit in all life stages?

    <p>Ticks are parasitic in all stages of their life cycle, using sensory organs to detect hosts for feeding.</p> Signup and view all the answers

    Explain the importance of larval feeding before pupation in myiasis flies.

    <p>The feeding larvae store energy needed for their transition into adult flies, supporting their reproductive success.</p> Signup and view all the answers

    What feeding adaptations distinguish the larvae of myiasis flies from adult flies?

    <p>Larvae have specialized mouthparts for parasitism, while adults are not adapted for feeding on hosts.</p> Signup and view all the answers

    How do harvest mite larvae differ from their nymph and adult stages in terms of feeding?

    <p>Harvest mite larvae are blood-feeding and parasitic, while nymphs and adults do not feed on hosts.</p> Signup and view all the answers

    What role do sensory organs play in the parasitism of Ixodes ricinus tick larvae?

    <p>Sensory organs help tick larvae detect hosts, ensuring successful blood feeding.</p> Signup and view all the answers

    How do the labella of certain parasites assist in feeding?

    <p>The labella's teeth rasp against the skin to create an opening for feeding.</p> Signup and view all the answers

    What is the role of jaw-like chelicerae in blood-feeding parasites?

    <p>They incise the epidermis to facilitate blood feeding by creating a wound.</p> Signup and view all the answers

    Describe the function of the hypostome in blood-feeding parasites like ticks.

    <p>The hypostome acts as a barbed tube for attachment and blood intake.</p> Signup and view all the answers

    What adaptations do temporary parasites possess to find and attach to hosts?

    <p>They utilize their antennae, wings, and powerful legs to locate and adhere to hosts.</p> Signup and view all the answers

    How do sponging mouthparts function during the feeding process of house flies?

    <p>They act like sponges to absorb liquid secretions from the host's mucous membranes.</p> Signup and view all the answers

    What is a key feature of the mouthparts of Ixodes ricinus ticks?

    <p>The mouthparts include jaw-like chelicerae and a hypostome for blood feeding.</p> Signup and view all the answers

    What is the significance of the barbed structure of the hypostome in ticks?

    <p>It ensures that the tick remains securely attached to the host during feeding.</p> Signup and view all the answers

    What method do fleas employ to enhance their attachment to hosts?

    <p>They secrete anesthetic substances to avoid detection and removal by the host.</p> Signup and view all the answers

    What is the significance of a large surface to volume ratio for Sarcoptes scabiei?

    <p>It helps them remain hydrated and survive while living in their host's skin, but limits their survival outside the host to a few days.</p> Signup and view all the answers

    Explain the role of female flies in mechanical transmission of pathogens.

    <p>Female flies can transmit pathogens on their mouthparts as they take multiple blood meals and lay eggs.</p> Signup and view all the answers

    What happens to pathogens in ticks during their life cycle stages?

    <p>Pathogens survive during moulting and must migrate from the tick's gut to its salivary glands before transmission to another host.</p> Signup and view all the answers

    Why is trans-statial biological transmission significant in the life cycle of three-host ticks?

    <p>It allows ticks to feed on different hosts at each life stage, enhancing the spread of pathogens between multiple vertebrate hosts.</p> Signup and view all the answers

    What distinguishes biological transmission from mechanical transmission in the context of arthropods?

    <p>Biological transmission involves the pathogen's survival and development within the vector, whereas mechanical transmission does not.</p> Signup and view all the answers

    How are the mouthparts of arthropods adapted to facilitate feeding on hosts?

    <p>Mouthparts may include hooks, combs, or cutting structures that assist in anchoring and obtaining blood or tissue from hosts.</p> Signup and view all the answers

    Describe how the structure of the hypostome benefits blood-feeding parasites.

    <p>The hypostome anchors the parasite securely to the host, preventing detachment during feeding.</p> Signup and view all the answers

    What is the impact of the flattened body shape of fleas on their parasitic lifestyle?

    <p>It allows fleas to navigate easily through dense fur or hair, enhancing their ability to attach and feed from their hosts.</p> Signup and view all the answers

    What is a key characteristic that distinguishes yeasts from moulds?

    <p>Yeasts are unicellular. (A)</p> Signup and view all the answers

    Which class of fungi is associated with producing ascospores?

    <p>Ascomycota (A)</p> Signup and view all the answers

    What type of hyphae do fungi of the Zygomycota phylum exhibit?

    <p>Non-septate hyphae (B)</p> Signup and view all the answers

    Which of the following is a distinguishing feature of pathogenic fungi?

    <p>Ability to grow at 37oC (D)</p> Signup and view all the answers

    What defines dimorphic fungi?

    <p>They can exist in both unicellular and multicellular forms. (A)</p> Signup and view all the answers

    Flashcards

    Partial Metamorphosis

    Insect life cycle where juvenile stages resemble adults, called nymphs.

    Complete Metamorphosis

    Insect life cycle with distinct juvenile (larva) and adult stages, with a pupal stage in between.

    Insect Nymph

    The juvenile stage of insects undergoing incomplete metamorphosis; resembles a smaller adult.

    Insect Larva

    Juvenile stage of insects undergoing complete metamorphosis; often adapted for feeding and growth.

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    Flea Life Cycle

    Typical life cycle involves eggs, nymphs, and adults; adults lay eggs repeatedly on host.

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    Head Louse Life Cycle

    Life cycle is about two weeks, eggs (nits) cemented to hair, nymphs moult, adults reproduce.

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    Arachnida Characteristics

    Four pairs of legs in both nymphs and adults, fused cephalothorax and abdomen, no antennae.

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    Parasitic Disease Diagnosis

    Understanding insect life cycles helps identify parasites and their stages of development.

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    Arthropod Life Cycle

    The series of stages in the life of an arthropod, from egg to adult, often with molting.

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    Flea Larva

    A stage in a flea's life cycle that feeds on digested blood.

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    Host

    An organism that provides food and/or shelter for another organism.

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    Moulting

    The process of shedding an exoskeleton or skin.

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    Life Cycle Impact on Control

    Understanding an arthropod's life cycle can help devise effective control measures.

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    Tick Life Cycle

    Ticks have a complex life cycle with different stages, a three host tick has adult, larva, and nymph stages, which feed on different animals and moult between stages.

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    Parasitic Adaptations

    Specific characteristics that help parasites survive and reproduce in their host environment, like a chitinous exoskeleton for protection.

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    Permanent Parasitism

    A parasitic relationship where the parasite lives on its host for the entire life cycle, unlike ticks which are temporary.

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    Temporary Parasitism

    A parasitic association where the parasite visits its host only for a blood meal and then leaves, like midges or poultry mites.

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    Rhipicephalus (Boophilus) microplus

    A type of tick that produces large numbers of offspring to maintain its population, meaning it may have more offspring than other types of insects.

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    Sheep Ked (Melophagus ovinus)

    An example of a permanent ectoparasite, a wingless fly with specific body adaptations for a parasitic lifestyle.

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    Poultry Red Mite (Dermanyssus gallinae)

    An example of a temporary ectoparasite that feeds on birds' blood at night. It spends most time away from host in daytime.

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    Ectoparasite

    Parasites that live on the surface of another organism.

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    Endoparasite

    Parasites that live inside the body of another organism.

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    Chewing Mouthparts

    Mouthparts designed for chewing, often strong and powerful, with mandibles acting like jaws. Examples include chewing lice.

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    Tearing Mouthparts

    Mouthparts specialized for tearing host tissue, usually large, strong, and curved hooks. Found in myiasis fly larvae.

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    Cutting & Slashing Mouthparts

    Mouthparts adapted to slice and cut skin. Examples include midges and tabanids.

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    Hypodermic Tubes

    Mouthparts resembling hypodermic needles used for piercing and sucking blood. Seen in mosquitoes, stable flies, and sucking lice.

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    Blood-Feeding Mouthparts

    Mouthparts adapted for feeding on blood. They can be cutting, slashing, or piercing.

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    Proboscis Structure

    A long, forward-projecting structure used for piercing and sucking. Commonly found in blood-feeding insects like mosquitoes.

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    Stable Fly Mouthparts

    Mouthparts adapted for piercing skin and sucking blood. They have a proboscis for piercing and labella for sponging.

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    Mouthpart Adaptation

    The evolution of specialized mouthparts in insects to effectively feed on different food sources, including blood.

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    House Fly Mouthparts

    House flies have sponging mouthparts adapted for absorbing liquid food, like secretions or blood. Their mouthparts are complex but designed for sponging and extend only during feeding.

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    Chelicerae

    Chelicerae are jaw-like appendages found in arthropods like ticks. They are used to pierce the host's skin, creating an entry point for the hypostome.

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    Parasite Adaptation: Flattened Body

    Some parasites, like fleas, have flattened bodies to move easily through dense fur or hair coats, allowing them to stay securely attached to their host.

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    Parasite Adaptation: Hooks & Combs

    Parasites may use hooks, combs, or scales on their bodies to help them cling firmly to their host, preventing them from being dislodged.

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    Parasite Adaptation: Large Surface Area

    Some parasites, like Sarcoptes scabiei, have a large surface area to volume ratio, allowing them to survive for longer periods away from their host.

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    Mechanical Transmission

    A type of pathogen transmission where the vector (carrier) doesn't play a role in the pathogen's life cycle, simply carrying it on its body.

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    Biological Transmission

    A type of pathogen transmission where the vector is actively involved in the pathogen's life cycle, requiring the pathogen to multiply within the vector before transmission.

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    Trans-stadial Transmission

    A type of biological transmission in ticks, where pathogens survive through multiple life stages (larvae, nymphs, adults) and can be transmitted by a single tick.

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    Pathogen Movement: Gut to Salivary Glands

    For some pathogens transmitted by ticks, they must move from the tick's gut to its salivary glands before they can be transmitted to a new host.

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    Three-host Tick Transmission

    Some ticks require three different hosts throughout their life stages, with each stage feeding on a different host, allowing for efficient transmission of pathogens.

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    What helps diagnose parasitic diseases?

    Understanding the life cycles of parasites, particularly the different stages they go through, helps in identifying infections and determining the best treatment strategies.

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    What are the key features of Arachnida?

    Arachnids, like ticks and mites, have four pairs of legs in both nymph and adult stages, a fused head and chest (cephalothorax), and no antennae.

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    How are Nits and Eggs linked?

    Nits are the eggs of lice, specifically the human head louse, Pediculus humanis capitus. These eggs are cemented to hair shafts by the female louse.

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    What is the significance of the Flea's life cycle?

    Fleas, like the Spilopsyllus cuniculi that infects rabbits, have a complete metamorphosis with eggs, larvae, pupae, and adults. Females lay eggs continuously, and adults feed repeatedly on hosts.

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    How do Blood-Sucking Lice reproduce?

    Blood-sucking lice, like the human head louse, undergo partial metamorphosis. They lay eggs on hair shafts, and nymphs molt three times before becoming sexually mature adults.

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    Why is understanding insect life cycles important?

    Understanding insect life cycles helps us target control measures effectively. By knowing the different stages of a parasite's life cycle, we can design treatments to disrupt their development and spread.

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    Chitinous Exoskeleton

    A hard outer covering that protects arthropods from desiccation, pathogens, and predators.

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    Desiccation

    The process of drying out due to loss of moisture.

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    Adaptation

    A trait or characteristic that helps an organism survive and reproduce in its environment.

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    Life Cycle Implications for Control

    Understanding an arthropod's life cycle is crucial for managing infestations. Targeting vulnerable stages like eggs, larvae, or nymphs can be more effective than simply killing adults.

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    Three Host Tick Cycle

    Ticks go through three stages: larva, nymph, and adult. Each stage requires a different host for feeding and development. This allows efficient transmission of pathogens, as the tick can spread disease across multiple hosts.

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    Survival Strategies During Adversity

    Arthropod parasites have developed strategies to survive harsh conditions, including entering a dormant state (like eggs or pupae), molting, or spending time hidden within the host.

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    Reproductive Strategies of Parasites

    Most arthropod parasites reproduce rapidly, taking advantage of favorable conditions. This results in large population increases, often leading to outbreaks or infestations.

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    Pharate Stages

    These are transitional stages in an arthropod's life cycle where significant development occurs; they are often hidden within the previous stage's exoskeleton.

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    Myiasis Fly Larvae

    Myiasis fly larvae are parasitic and feed on living tissue, causing skin lesions and potential harm to the host.

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    Harvest Mite Larvae

    Harvest mite larvae are parasitic, feeding on blood with their mouthparts. They're only parasitic in this stage, not as nymphs or adults.

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    Sheep Blow Fly Larvae

    Sheep blow fly larvae, or maggots, are parasitic and feed on living tissue, often causing serious skin damage and infections in sheep.

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    Parasitism in Arthropod Life Cycles

    Many arthropods are only parasitic during specific stages of their life cycle, having different ways of feeding and surviving as larvae, nymphs, or adults.

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    Implications of Arthropod Adaptations for Control

    Understanding different feeding adaptations and life cycle stages of arthropods is crucial for developing effective control methods.

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    Mouthparts for Blood-Feeding

    Arthropods have evolved different mouthparts specialized for piercing, cutting, or sucking blood from their hosts, depending on their feeding habits.

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    Adaptation: Flattened Body

    Some parasites have thin bodies to move easily through dense fur or hair.

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    Adaptation: Hooks and Combs

    Hooks and combs on the parasite's body help it cling to its host.

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    Adaptation: Large Surface Area

    Helps parasites survive for longer periods away from their host.

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    Gut to Salivary Glands

    Pathogens in ticks must move from the gut to the salivary glands for transmission.

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    Labella with teeth

    These are found at the end of the labium in insects, especially those with sponging mouthparts. The teeth help them rasp and pierce the skin during feeding.

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    Sponging mouthparts

    This type of mouthpart acts like a sponge, absorbing secretions or liquids from mucous membranes or even blood. Examples include house flies, face flies, and horn flies.

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    Mite and tick feeding mouthparts

    These include sharp chelicerae that cut the skin, and a hypostome (like a tube) for sucking blood. Together, they form a barbed feeding tube.

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    Hypostome function

    This structure in ticks is a specialized part of their mouthparts that acts like a tube. It inserts into the host's skin after the chelicerae pierce it, allowing blood to be sucked up.

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    How ticks feed

    Ticks have special mouthparts - sharp chelicerae cut the skin, making way for the hypostome, a tube-like structure, to be inserted into the skin for blood feeding.

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    Adaptations for parasitic behaviour

    Parasites have special features to help them find, attach to, and feed from their hosts. These adaptations are key to their survival.

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    Fleas and their hosts

    Fleas are highly adapted to find, attach to, and feed from their hosts. They have features like strong legs for jumping and sharp mouthparts for biting.

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    Fungal Pathogens

    A small group of fungi capable of causing infections in healthy individuals, with only around 400 species out of 148,000 known fungi considered pathogenic.

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    Dimorphic Fungi

    Fungi that can switch their form between a single-celled yeast shape and a filamentous mold shape, depending on environmental conditions.

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    Septate Hyphae

    Fungal filaments (hyphae) that have cross-walls (septa) dividing them into cells, allowing for efficient transport and nutrient exchange.

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    Conidia (Conidiospores)

    Asexual spores produced by fungi, particularly molds, that are important for dissemination and identification.

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    Germ Tube Formation

    A projection (germ tube) extending from a parent yeast cell, involved in the process of budding and reproduction.

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    Study Notes

    Arthropods as Parasites and Vectors

    • Arthropods are a diverse group of invertebrates that make up 80% of known animal species
    • They possess a hard exoskeleton, segmented bodies, and jointed limbs
    • They can be classified as insects (Insecta) or arachnids (Arachnida)
    • Some arthropods act as parasites
    • Other arthropods are vectors of pathogens
    • Examples of different arthropod groups that act as parasites and/or vectors include mites, ticks, lice, fleas, and flies
    • Understanding arthropod biology is critical to controlling parasitic diseases
    • Arthropod biology learning outcomes include understanding their roles as veterinary parasites and vectors, and diversity in life cycles and adaptations to parasitic life. This understanding aids in parasite control.

    Arthropod Biology

    • Arthropods have circulatory systems driven by a heart, which circulates haemolymph through an open system.
    • Sensory organs are concentrated in the cerebral ganglion region. This is where two nerve chords join
    • Mouthparts have various forms adapted for their function - this is for food acquisition (e.g. piercing, sucking, chewing).
    • Excretory organs are malpighian tubules
    • Insects have tracheal tubes for gas exchange
    • Insects have three pairs of legs in the adult form and one pair of antennae

    Arachnids

    • Arachnids have four pairs of legs in nymphs and adults.
    • They have no antennae.
    • Their body parts are fused (cephalothorax and abdomen).

    Insect Life Cycles - Metamorphosis

    • Partial Metamorphosis:
      • Juvenile stages closely resemble adults
      • Development happens in a series of stages called nymphs
      • The insect sheds its cuticle during development in 4–5 stages, increasing in size with each stage
    • Complete Metamorphosis:*
      • There are significant differences between juvenile and adult stages
      • The juvenile stages are referred to as larvae, maggots, or grubs, which are adapted for feeding and growth
      • During metamorphosis, there is restructuring of the entire body in the pupa stage
      • Examples include flies, mosquitos, and fleas

    Life Cycle of the Human Head Louse (Pediculus humanus capitus)

    • Adults are sexually reproductive
    • Life cycle completed in ~2 weeks
    • Females attach eggs to hair shafts
    • Nymphs hatch from eggs
    • Nymphs moult three times before becoming adults

    Arachnida Life Cycles - Partial Metamorphosis

    • A basic life cycle consists of 4 stages (egg, 6-legged larva, 8-legged nymph, 8-legged adult)
    • some genera have further division into intermediate stages (pre-larva, larva, protonymph, deutonymph, trinymph, adult)
    • There is moulting between growth stages

    Three Host Tick Life Cycle

    • Eggs are laid on the grounds by adult female
    • Larvae hatch and feed on host
    • Larvae drop and moult to nymphs
    • Nymphs feed on host
    • Nymphs drop and moult to adults
    • Adults feed/mate on a host

    Arthropod Parasite Reproductive Strategies

    • Life cycles are geared to take advantage of favorable conditions for fast population expansion
    • Survival during adverse conditions (e.g. during pupation, moulting, or a pharate stage) is important to species continuation.

    Adult Arthropod Parasite Biology

    • Chitinous exoskeletons protect arthropods from pathogens, predators, and desiccation.
    • Most arthropods are ectoparasites (live on their hosts) but some are endoparasites (live inside their hosts)

    Adult Arthropod Parasite Biology - Permanent Parasites

    • Some mites and keds live as permanent parasites

    Adult Arthropod Parasite Biology - Temporary Parasites

    • Some arthropods (e.g. midges and some mites) only visit hosts for brief blood meals

    Adult Arthropod Parasite Biology - Developmentally Parasitic

    • Examples of this include myiasis flies and some harvest mites.

    Life Cycle of the Cat Flea (Ctenocephalides felis)

    • Females lay eggs continuously
    • Eggs, containing blood, drop into environment
    • Larvae feed on partly digested blood faeces
    • The transition from larva to pupa to adult is a complete metamorphosis

    Life Cycle of the House Fly (Musca domestica)

    • Adults are parasitic
    • Sponging mouthparts
    • Eggs are laid in the environment (e.g. dung, rotting organic matter)
    • Larvae (maggots) develop in same environment
    • Larvae have three stages
    • Larvae develop into pupae in the same environment
    • Adults develop from this pupae

    Insect Larvae

    • Fly larvae extensively feed as the way to support the adults for survival.
    • Some larvae are parasitic, like the myiasis fly larvae

    Arachnid Larvae

    • Ticks and most mites are parasitic through all their life stages
    • This is not true for all mites though

    Parasitic Adaptations for Feeding

    • Different mouthparts adapted to different feeding mechanisms (e.g. chewing lice, mosquito, fly, tick)
      • Chewing - adapted for skin scales/hair
      • Tearing - large, strong, curved hooks
      • Sponging - act as sponges for secretions from surfaces
      • Cutting and slashing - for midges and tabanids
      • Hypodermic tubes (mosquitoes and stable flies)

    Other Adaptations for Parasitic Behaviour

    • Temporary parasites find hosts using sensory organs (wings, eyes, antennae, powerful legs)
    • Temporary parasites often eat rapidly, adhere strongly or secrete anaesthetics to avoid removal by their host
    • Permanent parasites remain on their hosts using hooks, combs, or scales

    Arthropods as Transmitters of Pathogens

    • Mechanical Transmission: No life cycle involvement of pathogens in parasite vector or development of pathogens within the vector
    • Biological Transmission: transfer of pathogens between hosts in blood-feeding cycles. Pathogens must survive within vector and move from the gut to the mouthparts before being transmitted to another host
      • Pathogens survive through moulting stages. They must move from the gut to the salivary glands for transmission to a new host

    Arthropod Vectors

    • Survival and replication within the vector is often a significant stage in a pathogen life cycle (e.g. bluetongue, African horse sickness, tick-borne fever, babesiosis)
    • Many pathogens are spread by feeding or blood taking
    • Transmission by biting or other activities of the vector

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    Explore the role of arthropods as both parasites and vectors in disease transmission. This quiz covers their classification, biological features, and the importance of understanding their life cycles and adaptations for effective parasite control. Delve into examples like mites, ticks, and fleas.

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