science

Parasitic flies of domestic animals

Parasitic flies of domestic animals is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Parasitic flies of domestic animals rather than just read about it. In short: Many species of flies of the two-winged type, order Diptera, such as mosquitoes, horseflies, blowflies, and warbleflies, cause direct parasitic disease to domestic animals, and transmit organisms that cause diseases. These infestations and infections cause distress to companion animals, and in livestock industry the financial costs of these diseases are high.

Key takeaways

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Reference excerpt

Many species of flies of the two-winged type, order Diptera, such as mosquitoes, horseflies, blowflies, and warbleflies, cause direct parasitic disease to domestic animals, and transmit organisms that cause diseases. These infestations and infections cause distress to companion animals, and in livestock industry the financial costs of these diseases are high. These problems occur wherever domestic animals are reared. This article provides an overview of parasitic flies from a veterinary perspective, with emphasis on the disease-causing relationships between these flies and their host animals. The article is organized following the taxonomic hierarchy of these flies in the phylum Arthropoda, order Insecta. Families and genera of dipteran flies are emphasized rather than many individual species. Disease caused by the feeding activity of the flies is described here under parasitic disease. Disease caused by small pathogenic organisms that pass from the flies to domestic animals is described here under transmitted organisms; prominent examples are provided from the many species.

Summary of types of disease associated with types of dipteran flies Disease caused by the feeding activity of dipteran flies is described here under parasitic disease. Disease caused by small pathogenic organisms that pass from the flies to domestic animals is described here under transmitted organisms; these organisms are often of numerous species thus only prominent examples are provided. Feeding by adult flies may cause irritation through acute stress from painful bites, resulting in loss of grazing time and reduced gain in weight. Feeding by adult flies on the blood of their hosts exposes the hosts to pathogenic organisms that are infecting the fly, this can lead to acute disease of the host's blood and other organs. Feeding by adult flies using their sponging mouthparts can also expose the hosts to pathogenic organisms that have contaminated the mouthparts. Larvae of some flies are adapted to feed on the tissues of their host, causing direct pathological damage to organs; this is known as myiasis.

Outline classification (families of main veterinary importance)

Class Insecta Order Diptera (two-winged flies) suborder Nematocera Family Culicidae (mosquitoes) Family Ceratopogonidae (biting midges) Family Psychodidae (sandflies) Family Simuliidae (blackflies) suborder Brachycera Family Tabanidae (horseflies) Family Muscidae (houseflies and others) Family Glossinidae (tsetse flies) Family Calliphoridae (blowflies) Family Oestridae (botflies and others) Family Hippoboscidae (louseflies) (Note that the former suborder Cyclorrhapha is now usually classified as part of the Brachycera.)

Nematocera (suborder)

General characteristics Antennae are usually long, with many similar and symmetric segments. These are small to very small flies, usually of delicate morphology with relatively long legs and wings. Body and wings are often covered in fine scales. Thorax is distinctly humped, abdomen is elongated. All species of veterinary and medical importance are blood feeders, with various types of mouthparts (these variations do not relate clearly to dipteran taxonomy).

Lifecycle is a complete metamorphosis with larvae that are parasitic, living in environments such as pools of water, soil, and streams. A complete metamorphosis is illustrated by the photograph of Stomoxys eggs, larvae, and adult (Stomoxys are in suborder Brachycera). Only females feed on blood, taking a large meal to support production of several hundred eggs, followed by several more cycles of blood meal followed by egg laying. Males feed on plant nectar and similar sources of sugars.

Disease relations Nematocerans are very important as transmitters of viruses, protozoa, and nematode worms. Also, they are often important for biting stress when in large numbers, and may cause allergic reactions at their feeding sites. A typical pathway of transmission of organisms by blood-feeding flies is shown below as a virus transmitted by an adult fly that feeds repeatedly on several hosts (see diagram for Biological transmission, and photograph of Culicoides). Insects that transmit pathogenic organisms are commonly known as vectors. The diagram shows what is known as biological transmission (= developmental transmission) because it is necessary for the transmitted organism to develop in the fly to the state where the organism is at an infective stage of its lifecycle. The repeated cycles of egg laying and feeding of the female fly (= gonotrophic cycle) provides the opportunity for the transmitted organisms to develop, multiply, and be exposed to further vertebrate hosts where they can complete their lifecycle. Only the adult flies are involved in this biological transmission, in contrast to biological transmission by other arthropods such as lice or ticks in which all active stages of the lifecycle feed on blood.

Mosquitoes (family Culicidae) Typical genera are Culex, Aedes, and Anopheles

Morphology, lifecycle, hosts, and feeding The basic structure of dipteran flies is illustrated in the diagram. Veterinary parasitology also covers arthropods in the class Acari, the ticks of domestic animals, and mites of livestock, which have distinctly different structure from arthropods in the class Insecta. However, flies in the order Diptera show clear division of the body into head, thorax, and abdomen with distinct segmentation of the thorax and abdomen. The thorax contains large blocks of muscle that power the single pair of wings. Digestive and reproductive organs fill the abdomen. Also unique to the Diptera is a pair of halteres (derived from wings during evolution) that aid agile flight by these flies. Mosquitoes have veined and scaled wings, long legs, and long hypodermic mouthparts sheathed in a protective labium (see photograph of Aedes female engorged with blood). Adult females lay eggs in batches on surfaces of stagnant water. Larvae feed on microorganisms and organic detritus in water. Pupation occurs at the surface of the water. Feeding by females is on a wide variety of mammals and birds, whilst males feed on plant sugars.

Parasitic diseases and transmitted organisms

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Parasitic flies of domestic animals

Start with the simplest possible case. Write down what Parasitic flies of domestic animals claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Parasitic flies of domestic animals before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Parasitic flies of domestic animals ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Parasitic flies of domestic animals

In research: Parasitic flies of domestic animals appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Parasitic flies of domestic animals in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Parasitic flies of domestic animals is common in secondary-school and first-year university syllabi. It links to neighbouring topics Parasites of animals, Parasitic flies, so understanding it makes those chapters shorter.
In everyday life: Look for Parasitic flies of domestic animals outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Parasitic flies of domestic animals in 20 minutes

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Frequently asked questions

What is Parasitic flies of domestic animals in simple terms?

Why does Parasitic flies of domestic animals matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Parasitic flies of domestic animals?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Parasitic flies of domestic animals.