All About Diptera

• The Diptera order, or true flies, is the largest and most diverse order of insects, anatomically varied, and ecologically exploitive
• Diptera means "two-winged" referring to having two wings
• Worldwide, there are at least 152,000 species described
• The Nearctic Region contains around 20,000 Dipteran species.
• Diptera can impact on human and animal health, with only a small fraction of the species having medical significance.
• Diptera also includes Mosquitoes to wingless ectoparasites
• Diptera can transmit Malaria, encephalitis, yellow fever, human filariasis, and Zika

Culicidology

• Malaria, Filariasis, Leishmaniasis, and onchocerciasis are diseases which affect half a billion humans with 3.5 billion rated at risk
• Mosquitoes, blackflies, and biting midges annoy outdoor enthusiasts and livestock, pets, and other domestic, and wild animals.
• Filth flies found near cattle, hog, and poultry operations can annoy residents and are often the focus of litigation
• Medicocriminal or forensic entomology includes flies (Diptera)

Fly Facts

• Ubiquitous species like the housefly can act as effective mechanical vectors of pathogens in enteric diseases
• The depredation of bloodsucking and myiasis-producing flies cause adverse effects on animal agriculture
• Diptera can be divided into two suborders Nematocera (mosquitoes-long antennae) and Brachycera (horse flies, deer flies-short antennae)
• Genetic, molecular, morphological, and paleontological datasets show that "Nematocera" is a paraphyletic group of superficially similar lineages
• Hematophagy arose within Diptera in 12 separate occasions.
• Larval endo-parasitism and Ecto-parasitism occurred 17 and 10 times relatively
• The loss of functional wings occurred 18 times.

Diptera Life History

• The Diptera are holometabolous (complete metamorphosis)
• Most dipteran females lay eggs (Oviparous)
• Other diptera are oviviviparous, hatching eggs internally (larviparous), e.g. flash flies (Sarcophagidae).
• Pupiparous flies will retain developing larvae until they pupate, e.g., louse flies (Hippoboscidae)
• Immature fly stages often colonize aquatic or semi-aquatic habitats, including mosquitoes, black flies, most deer flies and horse flies
• Mosquitos and most other nematocerans have 4 larva, instars
• Muscoid Diptera pass through three observable instars.
• Anautogenous diptera require a blood meal for egg laying
• Autogenous flies produce an initial egg batch before needing a blood meal.
• Adaptations among early aquatic instars depend on cuticular respiration
• The later instars generally respire via gills or have various adaptations that permit them to obtain atmospheric air.
• Mosquito larvae are highly adapted to their environment
• Air-breathing lower Diptera hang from the water's surface by respiratory siphons or specialized abdominal setae

Diptera Adult Features

• Nematocera have elongate, filamentous antennae composed of six or more segments.
• Nematocera antennae are longer than the head and thorax combined.
• Simuliidae have short and compact antennae.

Fly Behaviors

• Titer in CO2 is an olfactory cue for recognizing hosts, additional cues are mercaptans, octanol, and lactic acid
• Some flies also use visual cues for host selection
• K-strategists, such as tsetse flies and sheep keds, have longer life cycles, produce fewer offspring, and are influenced by density-dependent mortality factors
• R-strategists produce a large number of offspring, where each individual's survival chance is relatively small
• R-Strategists feature rapid growth, a short life cycle, and are influenced by a high mortality-density independent factor example being: house flies and certain mosquito

Crane Flies and March Flies

• Crane Flies are attracted to light and mistaken for large mosquitoes
• Crane Flies feed on nectar
• Crane Flies do not bite or feed on blood
• The Crane Fly family is Cosmopolitan with 60 genera and 1500 species in North America, and they have aquatic and semi-aquatic habitats.
• March Flies(Bibionidae) adults emerge in the spring and feed on flower nectar and pollen
• March Fly larvae are scavengers found in decaying organic materials like forest litter, manure, and humus-rich soils.
• March Fly larvae can damage cultivated plants, such as cereal and grass crops.
• Adults of the Love-bug (Plecia nearctica) emerge on the Gulf and south Atlantic coasts (May-September)
• Abundant flying March Fly pairs can pose a hazard to automobile travelers

Fungus Gnats and Phantom Midges

• Darkwinged Fungus Gnats (Sciaridae) are encountered in moist, and shady habitats.
• Fungus Gnat larvae feed on fungi, decaying plants, soybean, and clovers.
• Sciarids pose no medical problems, with rare reports of illness in pets after eating adults
• There are more than 100 Nearctic Fungus Gnat species
• Phantom Midges (Chaoboridae) are mosquito-like, but lack an elongate proboscis and abundant wing scales
• Phantom Midge eggs hatch within 2-4 days and are laid on the water surface
• Phantom Midge larval stage averages 15-32 days, and the pupa lasts 3-6 days actively
• Larvae are aquatic and transparent inhabiting large lakes, small pools, bogs, and small ponds
• The clear lake gnat is an inhabitant of large lakes and impoundments in the western USA
• Large numbers of Phantom Midges emerge synchronously in the spring, causing annoyance in residential and resort areas because of light attraction

Chironomid Midges

• Chironomid midges are mistaken for mosquitoes, but lack the blood-sucking proboscis
• Chironomid midges have slender legs, narrow scaleless wings, and plumose antennae in adult males
• Chironomid midges lack a long proboscis for feeding on blood, but are able to imbibe honeydew and other natural sugars
• Some midges take no food at all as adults
• Chironomid larvae are aquatic and create tubes or attach to substrates in different bodies of water
• It inhabits rivers, streams, lakes, ponds, water supplies, and sewage systems, and are the most abundant benthic organisms
• Common issues can arise from inhabitants developing allergies to the larval hemoglobin
• They cause annoyance to humans and cause economic damage to machinery, paint finishes, automobiles, and airplanes.
• The bacterium Vibrio cholerae has been isolated from chironomid egg masses
• Large numbers of adult midges can discourage tourism and contaminate materials, especially in pharmaceutical, food processing ,and manufacturing plants.
• The fly larvae can pass through taps into homes within water-storage and water distribution

Snipe Flies and Athericid Flies

• Snipe Flies (Rhagionidae) mostly prey on other insects
• In California Snipe Fly adults are active from April to July and readily attack domestic animals and mammals
• Snipe Flies inflict painful bites around heads, but they have not been implicated in transmitting disease agent
• Snipe Fly biting activity occurs in Yellowstone National Park, starting in early July and continuing till early September including a swarms that attack along trails
• Athericidae (Athericid flies) inhabit flowing water and predate on other insect larvae and have one generation per year
• Female Suragina species suck human and domestic animal blood as well as cold-blooded vertebrates.
• Six Nearctic Athericid species are present in Texas and Mexico, three being blood feeding genus suragina

Soldier Flies and Hunchback Flies

• Soldier Flies (Stratiomyidae) can have colored bodies(yellow, green, blue, or black) and also be of metallic appearance.
• Soldier fly adults visit flowers, cattails, and other emergent aquatic vegetation.
• Black soldier fly can become abundant in sewer processing plants with trickle filters, enough to block the system.
• Black soldier fly larvae can help in house fly control and reduction of pathogens, especially in manure
• Black soldier fly larvae can be consumed by humans through over ripe fruit or undercooked meat, resulting in intestinal myiasis
• Hunchback (Phoridae) appearance is characteristic and humpbacked
• Hunchback Flies (Phoridae) run in short, quick bursts and are found in damp places near larval habitats
• Hunchback Fly habitats are extremely varied
• Hunchback larvae arrive late on decomposing bodies
• Megaselia scalaris, a species of humpbacked fly, is of noteworthy medical importance
• The laying of eggs takes place in decaying plants and animal waste such as dead insects, bird nets, sewage treatment beds, and commercial mushrooms
• Females lays eggs in fruits, decaying plants/or waste
• In humans they can cause cutaneous pneumonic, nasal, ophthalmomyiasis

Hover Flies, Skipper Flies and Fruit Flies

• Flower Flies (Syrphidae) are strong fliers that hover near nectar flowers
• They do not bite/ sting
• Syrphidae larvae inhabit social insects, various feeding habits
• Syrphidae are found in wastewater lagoons for livestock
• Syrphidae occasionally, E. tenax cause gasterointenstinal and urogenital myiasis
• The number of species are more than 900
• Skipper Flies live in a variety of dead plant and animal material, including food
• Skipper Flies are pests in stored cheeses
• Skipper Flies are consumed by humans and cause gastrointestinal distress
• Small Fruit Flies (Drosophilidae) have red eyes, and they have stalked posterior spiracles
• Fruit flies colonize decaying vegetation such as fruits, plants,sap, and fungi. Drosphilidae feed on the decaying substrate with yeast

Grass Flies

• Grass Flies (Chloropidae have adults that are commonly found in grasses and other low vegetation, or visiting flowers
• Larvae lack an apparent head
• Most larvae are phytophagous
• Grass Flies are attracted to humans and other mammals
• Liohippelates, eye gnats, species have resulted in mechanical transmission in livestock/mammals
• There are approximately 270 species in the Nearctic region

Zoonotic Diseases

• One Health is an approach which requires collaboration across disciplines and sectors, promoting the best health outcomes for animals, plants, and the environment
• One Health aims at achieving optimal health outcomes recognizing the interconnection between people, animals, plants, and their shared environment
• Changes to human populations, climate and land use, and international travel and trade have caused new/emerging or existing zoonotic diseases
• Zoonotic diseases are those which are transmitted to animals from people or vice versa
• Zoonotic diseases include: rabies, salmonella infection, west nile virus, Q Fever(Coxiella burnetii), Anthrax, Brucellosis, Lyme disease, Ringworm, and Ebola
• Germs(Zoonoses) can be transmitted through direct/indirect contact, and exposure to vectors, food/water contamination
• "One Health" addresses issues such as zoonotic diseases, antimicrobial resistance, food saftey, food security, and environmental contamination
• One Health is a collaboration of human health, animal health, environment heath and more between sectors of law, policy,community and pet care