Conclusion of the Oestrids, Hippoboscids

1. Conclusion of the Oestrids, Hippoboscids Announcements Speaking today: Christie Lee Scott Next Tuesday: Ashlee Swinford Reminder: 1-hour exam next Thursday Chaps 11 (from ca. p. 157), 12, 13, 14, 15, 16, 17, 18, & 19 (about 200 pp of material).

2. Recap • Myiasis classified as Accidental, Facultative, or Obligatory. • Human cases can be any of these but “incidental obligatory” most common. • Also classified by affected tissue • Cutaneous myiasis is most common in humans • Furuncular is a kind of cutaneous • Nasopharyngeal myiasis is the most dangerous form

3. The flies themselves • Most (your book has others) are in one of two groups: • Groups comprised primarily of necrophages, some of which cause myiasis • necrophagous – eats flesh from dead bodies • sarcophagous – eats flesh from bodies; carnivorous • Note: sarcophagous ≠ sarcophagus (lacks 2nd “o”) • Oestridae – Highly evolved obligate flesh parasites of vertebrates.

4. Group 1: Calliphorid & Sarcophagids • Calliphoridae (Carrion & blow flies) & Sarcophagidae (flesh flies) • Most myiasis spp are necrophagous • Only a few are obligate myiasis spp. • Calliphorids include temporary myiasis spp. (Congo floor maggot, nest blow fly). • Tumbu flies are Calliphorids • Most economically important spp are the Screwworms, major livestock pests. • Old World Screwworm Chrysoma bezziana • New World Screwworm, Cochliomyia hominivorax

5. cluster fly Calliphorids includes blow flies, cluster flies, green/blue bottle flies. Below: carrion fly Above: green bottle fly

6. Most Sarcophagids cause accidental or facultative myiasis. Only a few are obligate. Typical Sarcophaga sp. Wohlfartia bella – Note the different color pattern on the abdomen

7. New World Screwworm • Mostly a livestock pest • Untreated myiasis results in animal death • Invasion produces more flies that lead to more infestation. • Wounds become infected, large number leads to septicemia. • Presence of flies leads to gadding (stampedes). Does not happen with bot flies that use egg porters. • Eradication has proven possible with this species.

9. Group 2 –Oestrids, Bot flies • Most highly evolved group • Highly species and tissue specific • Unusual biologies (e.g. no mouth, use of egg porters, etc.) Camel nose bot Squirrel bots are common in KY

10. About the Flies: Oestrids (Bot Flies) • Four Suborders • New World Skin Bots, Cuterebrinae. • Most are parasites of rodents & rabbits. • Tórsalo, Human bot fly, Dermatobia hominis. S. Mexico to Argentina • Old World Skin Bots, Hypodermatinae • Mostly parasitic on larger mammals. • Most important species are the cattle grubs (northern & southern).

11. About the Flies: Oestrids (Bot Flies) • Four Suborders • Nose Bots, Oestrinae. • Sheep bot is the most common. Can also infest human with very bad results. • Stomach Bots, Gasterophilinae • Horse bots previously mentioned

12. Tiny antennae, no mouths Human bot fly, Dermatobia hominis

13. Cattle grubs - $100 M/yr in US • Larvae of warble flies or heel flies • Most common species are Hypoderma bovis (northern) and H. lineatum (common) • Damage is from • Hide loss • Weight gain reduction • Milk production reduces 10 – 20% • Carcass value reduced • Gadding-related injury

14. Louse Flies, Keds • Hippoboscidae & related families • All are blood feeders • Most are parasitic on birds (pigeon flies, bird flies • Some are bat parasites (bat flies) • Humans come in contact in specific situations. • Deer keds & early season hunters • Sheep keds

15. Deer Keds • Swarm in mid-Sept. in our area • Newly emerged are winged & called “volants” • Shortly after landing on an acceptable host, the wings break off • Volants of NA spp. do not bite unsuitable hosts, other spp. do.

16. Sheep Keds • Live permanently on host, can only live a few days off host • Viviparous, about 1 larva/week • Wingless entire life • Most economically-important in this group.

17. Economic Impact of Sheep Keds • Degrades hide quality in texture & color • “Cockle” or “Ekek” is an allergic hypersensitivity to ked bites (cf. Fig. 19.11 in text). • Animals can become anemic • Some studies show weight gain and/or fleece production losses due to heavy infestation • Can be a significant irritant to sheep ranchers. • Some animals die as a result of avoidance attempts (e.g. “back loss”), similar to gadding.

18. Medical Importance of this group • Humans are not hosts of any species in this group but are sometime bitten. • Bite is painful & can be a nuisance. • Especially important is the pigeon fly which readily bites humans • In some places, volant swarms can cause epidemics of “deer ked dermatitis” • Implicated in the mechanical transmission of some diseases • Potential transmission of many diseases. • Multiple Bartonella spp. are routinely isolated from adults. Many veterinary examples of bartonellosis.

19. Fly Management

20. General Fly Management • Most fly management is host/site-centric with key disease/problems being the management objective(s) • e.g. Livestock fly management focuses on stable/face/horn flies, cattle grubs • e.g. Urban fly management focuses on mosquitoes & human disease reduction • Hospital fly management focuses on filth/house fly exclusion & elimination

21. Generic Fly Management Components • Fly management programs are generally divided into larval and adult components. • Vectored pathogens generally managed pharmacologically with prophylactic treatment used where available. • Therapeutic treatments not always available. • If available, therapeutic treatments are often expensive, have multiple contra-indications, not always well tolerated. • Disease diagnosis means damage has already occurred • For humans, education component is important. • There may be a disease/fly reservoir management component as well

22. Larval Fly Management • Source Reduction – Elimination of larval habitat and/or resources • Biological Control – Use of one organism to control another. Pest target is usually a future generation. • Conserving existing biological controls • Augmenting existing biological controls • Chemical Control – Contaminating larval habitat with an agent toxic to the larva. • Agent may be chemical or biological • If biological, pest target is usually the current generation.

23. Source Reduction for Larval Control • Reducing standing water • Reducing fecal material, rotting vegetable material • General sanitation Stable fly breeding ground Draining standing water in California Fly swarms in Cambodia garbage

24. Biological Control via predators, parasites • Some are commercially available (e.g. Muscidifurax raptor for house fly control). • Major emphasis of mosquito management in rice lands • Some cases of entomopathogens managed for larval control Above: Muscidifurax parasitizing fly pupae (left) and empty pupal cases after paratization Above: Fly maggot infested with parasitic nematodes that are killing the maggot.

25. Chemical Control (Insecticides), • Applied to larval habitat • Non-parasitic larvae: General environmental application for typical insecticides • Parasitic Larvae: Oral/Dermal/Suppository/Parenteral application of avermectins (vertebrate systemics) • Synthetic analogues of a soil microbial extract found in Japan, 1978