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Datasheet

Chrysomya bezziana (Old World screw-worm)

Summary

  • Last modified
  • 13 July 2017
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Chrysomya bezziana
  • Preferred Common Name
  • Old World screw-worm
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta
  • Summary of Invasiveness
  • The first specimens of Chrysomya bezziana were recovered from myiases on cattle hosts in the Congo, Central Africa in 1909 (Rovère, 1910). The endemic distribution of...

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Pictures

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PictureTitleCaptionCopyright
Chrysomya bezziana (Old World screw-worm); oviposition - females laying eggs on a wounded steer.
TitleOviposition
CaptionChrysomya bezziana (Old World screw-worm); oviposition - females laying eggs on a wounded steer.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); oviposition - females laying eggs on a wounded steer.
OvipositionChrysomya bezziana (Old World screw-worm); oviposition - females laying eggs on a wounded steer.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); pair copulating.
TitleAdults mating
CaptionChrysomya bezziana (Old World screw-worm); pair copulating.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); pair copulating.
Adults matingChrysomya bezziana (Old World screw-worm); pair copulating.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); females ovipositing on wounded steer.
TitleOviposition
CaptionChrysomya bezziana (Old World screw-worm); females ovipositing on wounded steer.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); females ovipositing on wounded steer.
OvipositionChrysomya bezziana (Old World screw-worm); females ovipositing on wounded steer.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); wound myiasis - early stage of myiasis, with second and early third instar larvae of C.bezziana in a feeding aggregation.
TitleEarly stage of myiasis
CaptionChrysomya bezziana (Old World screw-worm); wound myiasis - early stage of myiasis, with second and early third instar larvae of C.bezziana in a feeding aggregation.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); wound myiasis - early stage of myiasis, with second and early third instar larvae of C.bezziana in a feeding aggregation.
Early stage of myiasisChrysomya bezziana (Old World screw-worm); wound myiasis - early stage of myiasis, with second and early third instar larvae of C.bezziana in a feeding aggregation.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); mature third instar larvae in a bovine wound.
TitleThird instar larvae
CaptionChrysomya bezziana (Old World screw-worm); mature third instar larvae in a bovine wound.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); mature third instar larvae in a bovine wound.
Third instar larvaeChrysomya bezziana (Old World screw-worm); mature third instar larvae in a bovine wound.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); larvae evacuating the wound after completing feeding.
TitleFinal instar larvae
CaptionChrysomya bezziana (Old World screw-worm); larvae evacuating the wound after completing feeding.
Copyright©DrJ. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); larvae evacuating the wound after completing feeding.
Final instar larvaeChrysomya bezziana (Old World screw-worm); larvae evacuating the wound after completing feeding.©DrJ. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiais of navel of new-born buffalo calf. Papua New Guinea.
TitleMyiais
CaptionChrysomya bezziana (Old World screw-worm); myiais of navel of new-born buffalo calf. Papua New Guinea.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiais of navel of new-born buffalo calf. Papua New Guinea.
MyiaisChrysomya bezziana (Old World screw-worm); myiais of navel of new-born buffalo calf. Papua New Guinea.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of bovine scrotum following castration. Papua New Guinea.
TitleMyiasis
CaptionChrysomya bezziana (Old World screw-worm); myiasis of bovine scrotum following castration. Papua New Guinea.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of bovine scrotum following castration. Papua New Guinea.
MyiasisChrysomya bezziana (Old World screw-worm); myiasis of bovine scrotum following castration. Papua New Guinea.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of sheep's rectum. Port Moresby, Papua New Guinea.
TitleMyiasis
CaptionChrysomya bezziana (Old World screw-worm); myiasis of sheep's rectum. Port Moresby, Papua New Guinea.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of sheep's rectum. Port Moresby, Papua New Guinea.
MyiasisChrysomya bezziana (Old World screw-worm); myiasis of sheep's rectum. Port Moresby, Papua New Guinea.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of sheep's vulva. Papua New Guinea.
TitleMyiasis
CaptionChrysomya bezziana (Old World screw-worm); myiasis of sheep's vulva. Papua New Guinea.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of sheep's vulva. Papua New Guinea.
MyiasisChrysomya bezziana (Old World screw-worm); myiasis of sheep's vulva. Papua New Guinea.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of dog. Port Moresby, Papua New Guinea.
TitleMyiasis
CaptionChrysomya bezziana (Old World screw-worm); myiasis of dog. Port Moresby, Papua New Guinea.
Copyright©Dr D.P.A. Sands-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of dog. Port Moresby, Papua New Guinea.
MyiasisChrysomya bezziana (Old World screw-worm); myiasis of dog. Port Moresby, Papua New Guinea.©Dr D.P.A. Sands-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of a cat (Felis catus). Port Moresby, Papua New Guinea.
TitleMyiasis
CaptionChrysomya bezziana (Old World screw-worm); myiasis of a cat (Felis catus). Port Moresby, Papua New Guinea.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis of a cat (Felis catus). Port Moresby, Papua New Guinea.
MyiasisChrysomya bezziana (Old World screw-worm); myiasis of a cat (Felis catus). Port Moresby, Papua New Guinea.©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis in human eye orbit.
TitleMyiasis
CaptionChrysomya bezziana (Old World screw-worm); myiasis in human eye orbit.
Copyright©Dr John Niblett-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); myiasis in human eye orbit.
MyiasisChrysomya bezziana (Old World screw-worm); myiasis in human eye orbit.©Dr John Niblett-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); imported Australian sheep with C.bezziana myiasis. Muscat, Sultanate of Oman.
TitleInfested sheep
CaptionChrysomya bezziana (Old World screw-worm); imported Australian sheep with C.bezziana myiasis. Muscat, Sultanate of Oman.
Copyright©Dr J. Philip Spradbery-All Rights Reserved
Chrysomya bezziana (Old World screw-worm); imported Australian sheep with C.bezziana myiasis. Muscat, Sultanate of Oman.
Infested sheepChrysomya bezziana (Old World screw-worm); imported Australian sheep with C.bezziana myiasis. Muscat, Sultanate of Oman.©Dr J. Philip Spradbery-All Rights Reserved

Identity

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Preferred Scientific Name

  • Chrysomya bezziana Villeneuve, 1914

Preferred Common Name

  • Old World screw-worm

International Common Names

  • English: Old World screwworm; Old World Screw-worm fly; screw worm

English acronym

  • OWS
  • OWSWF

Summary of Invasiveness

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The first specimens of Chrysomya bezziana were recovered from myiases on cattle hosts in the Congo, Central Africa in 1909 (Rovère, 1910). The endemic distribution of C. bezziana includes much of central Africa from Sierra Leone in the west to Kenya in the east and to northern South Africa, and probably widespread in Ethiopia and the Horn of Africa. In the Middle East, C. bezziana is endemic to Saudi Arabia, Iran, United Arab Emirates and Sultanate of Oman (Spradbery and Kirk, 1992; Spradbery et al., 1992) and has been accidentally introduced to Yemen, as well as Bahrain and Kuwait, the latter two countries through shipments of livestock passing the Gulf of Oman en route to ports in the Persian Gulf (Kloft et al., 1981). In 1996, a major outbreak occurred in Iraq, exacerbated by a lack of veterinary response due to United Nations sanctions on the country prevailing at that time. The only live incursion into Australia by C. bezziana was recorded in 1988, when a number of adult flies were recovered in an electrocutor trap aboard a livestock vessel that had just returned from delivering live cattle to Brunei (Rajapaksa and Spradbery, 1989).

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Diptera
  •                         Family: Calliphoridae
  •                             Genus: Chrysomya
  •                                 Species: Chrysomya bezziana

Notes on Taxonomy and Nomenclature

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Globally, there are two Screw-worm fly species, the Old World SWF (OWS) (Chrysomya bezziana) and the New World SWF (NWS) (Cochliomyia hominivorax) (Spradbery, 1994). The genus Chrysomya contains 11 described species, many of which are important in forensic and medical criminal taxonomy (James, 1947). C. bezziana is the only species in the genus of primary medical importance and is distributed in sub-Saharan Africa, Middle East, Indian subcontinent, SE Asia and New Guinea, where the larvae parasitize warm-blooded animals including livestock and humans. Chrysomya bezziana was first described by Professor Mario Bezzi of Turin, based on material collected from cattle in the Belgian Congo (now CDR) who identified them as Chrysomya megacephala, but later they were correctly identified as a new species by Joseph Villeneuve de Janti, and named Chrysomya bezziana, in honour of Professor Bezzi (Villeneuve, 1914).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

BahrainPresent, few occurrencesIntroduced Invasive Kloft et al., 1981; Hall et al., 2001
BangladeshPresentJames, 1947
CambodiaPresentNative Invasive James, 1947
-FujianPresent,
-Hong KongPresentIntroduced2000 Invasive Wardhana et al., 2012b; Ng et al., 2003; Ready et al., 2009
IndiaPresentNative Invasive James, 1947; Norris and Murray, 1964
-Andhra PradeshPresentNative Invasive Norris and Murray, 1964
-ChhattisgarhPresentNative Invasive Norris and Murray, 1964
-Dadra and Nagar HaveliPresentNative Invasive Norris and Murray, 1964
-DelhiPresent,
-GoaPresentNative Invasive ,
-HaryanaPresent,
-KarnatakaPresentNative Invasive Norris and Murray, 1964
-KeralaPresentNative Invasive Norris and Murray, 1964
-Madhya PradeshPresentNative Invasive Norris and Murray, 1964
-MaharashtraPresentNativeNorris and Murray, 1964
-OdishaPresentNative Invasive Norris and Murray, 1964
-RajasthanPresentNative Invasive ,
-Tamil NaduPresentNative Invasive Norris and Murray, 1964
-West BengalPresentNative Invasive Norris and Murray, 1964
IndonesiaPresentNative Invasive Wardhana et al., 2012b; Norris and Murray, 1964; Wardhana et al., 2014
-Irian JayaPresentNative Invasive Wardhana et al., 2012b; Norris and Murray, 1964; Wardhana et al., 2014
-JavaPresentNative Invasive Wardhana et al., 2012b; Norris and Murray, 1964; Wardhana et al., 2014
-KalimantanPresentNative Invasive Wardhana et al., 2012b; Wardhana et al., 2014
-Nusa TenggaraPresentNative Invasive Wardhana et al., 2012b; Wardhana et al., 2014
-SulawesiPresentNative Invasive Wardhana et al., 2012b; Norris and Murray, 1964; Wardhana et al., 2014
-SumatraPresentNative Invasive Wardhana et al., 2012b; Norris and Murray, 1964; Wardhana et al., 2014
IranPresentNative Invasive Wardhana et al., 2012b; Hall et al., 2001Boushehr and Hormozoan Provinces
IraqPresentNative Invasive Wardhana et al., 2012b; Hall et al., 2001Basrah, Karbala and Diayala Provinces
KuwaitPresentIntroduced Invasive Rajapaksa and Spradbery, 1989; Hall et al., 2001
LaosPresentNative Invasive James, 1947
MalaysiaPresentNative Invasive Wardhana et al., 2012b; Norris and Murray, 1964
-Peninsular MalaysiaPresentNative Invasive Norris and Murray, 1964
MyanmarPresentNative Invasive James, 1947; Norris and Murray, 1964; Hall et al., 2001
OmanPresentNative Invasive Wardhana et al., 2012b; Spradbery et al., 1992; Hall et al., 2009Al-Batina, Al-Shargiah and Interior Districts
PakistanPresentNative Invasive James, 1947; Hall et al., 2001
PhilippinesPresentNative Invasive James, 1947
QatarPresentNative Invasive Rajapaksa and Spradbery, 1989
Saudi ArabiaPresent Invasive Wardhana et al., 2012b; Ansari and Oertley, 1982; Hall et al., 2009Al-Khari, Al-Muzahimiyah, Al-Ehsaa
Sri LankaPresentNative Invasive James, 1947
TaiwanPresentNative Invasive Norris and Murray, 1964
ThailandPresentNative Invasive James, 1947
United Arab EmiratesPresentIntroduced Invasive Spradbery and Kirk, 1992; Hall et al., 2001
VietnamPresentNative Invasive James, 1947
YemenLocalisedIntroduced Invasive Wardhana et al., 2012b; Robinson et al., 2009

Africa

CameroonPresentNative Invasive Hall et al., 2001
ChadPresentHall et al., 2001
CongoPresentNative Invasive James, 1947
Congo Democratic RepublicPresentNative Invasive Rovere, 1910; Hall et al., 2014
Côte d'IvoirePresentNative Invasive James, 1947
Equatorial GuineaPresentNative Invasive James, 1947
EthiopiaPresentNative Invasive Hall et al., 2001Two localities: Gondar, Yabello
GambiaPresentNative Invasive James, 1947
GuineaPresentNative Invasive James, 1947
Guinea-BissauPresentNative Invasive Norris and Murray, 1964
KenyaPresentNative Invasive James, 1947
SenegalPresentNative Invasive Norris and Murray, 1964
South AfricaPresentNative Invasive Wardhana et al., 2012b; Baker et al., 1968; Hall et al., 2014East Cape Province
SudanPresentNative Invasive Hall et al., 2014
SwazilandPresentNative Invasive James, 1947
TanzaniaPresentNative Invasive Norris and Murray, 1964; Hall et al., 2014
-ZanzibarPresentNative Invasive James, 1947
UgandaPresentNative Invasive James, 1947
ZambiaPresentNative Invasive James, 1947
ZimbabwePresentNative Invasive Wardhana et al., 2012b; Cuthbertson, 1933; Hall et al., 2001; Hall et al., 2014

Oceania

Australia
-Australian Northern TerritoryAbsent, intercepted only Not invasive Rajapaksa and Spradbery, 1989Port Darwin,1988
Papua New GuineaPresentNativeNorris and Murray, 1964; Hall et al., 2001; Spradbery and Tozer, 2013

History of Introduction and Spread

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Chrysomya bezziana was first described from adults reared from larvae collected in cattle myiases in Kitoboli and Dolo, Belgian Congo (now CDR) by Joseph Rovère, a doctor and veterinarian (Villeneuve, 1914). The endemic distribution of C. bezziana includes much of tropical Africa, Arabia and the Middle East, the Indian subcontinent and SE Asia as far east as New Guinea. Introductions are made possible by the movement of host animals. For example, live sheep exports from Australia to Middle East ports resulted in sheep becoming infested at the port of Muscat in the Sultanate of Oman when unloading animals, followed by their subsequent offloading in Bahrain and Kuwait (Kloftet al., 1981). C. bezziana has been recorded in Australia on one occasion when a returning livestock vessel docked at Darwin after delivering cattle to Brunei. An electrocutor trap was set up on board the vessel after it had cleared customs and quarantine and 7 adult C. bezziana were subsequently captured (Rajapaksa and Spradbery, 1989). A passenger aboard a commercial flight from Sri Lanka to Kuala Lumpur in Malaysia was found to have a C. bezziana infestation (Pillai and Ramalingan, 1984). The accidental introduction of C. bezziana to Iraq in 1996 (Abdul Rassoul et al., 1996; Al-Izzi et al., 1999; Hall et al., 2001; Siddig et al., 2005) resulted in its rapid dispersal throughout the Tigris and Euphrates river systems with approximately 60,000 cases reported in livestock and humans within 2 years, with a mortality rate of 1 per cent in livestock (Spradbery and El-Dessouky, 1998).

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Bahrain Oman 1970s Animal production (pathway cause) Yes Kloft et al., 1981 Via live sheep exports to Gulf ports from Australia via Oman
Iraq 1996 Yes Hall et al., 2001; Siddig et al., 2005
Kuwait Oman 1970s Animal production (pathway cause) Yes Kloft et al., 1981 Via live sheep exports to Gulf ports from Australia via Oman
Qatar Oman 1970s Animal production (pathway cause) Yes Kloft et al., 1981 Via live sheep exports to Gulf ports from Australia via Oman
Yemen 2007 Yes Robinson et al., 2009

Risk of Introduction

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The most likely route for an incursion of Chrysomya bezziana to a new location is via an infested host animal, be it livestock or human. However, adult flies have been intercepted in passenger aircraft and returning livestock vessels arriving in Australian ports (Rajapaksa and Spradbery, 1989). C. bezziana remains present in Bahrain, Kuwait, Iraq and Yemen where it was accidentally introduced, but no further countries have experienced incursions resulting in successful colonization. Australia maintains an official state of awareness and preparedness with respect to a potential C. bezziana incursion (Animal Health Australia AUSVETPLAN, 2007).

Pathogen Characteristics

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Detailed descriptions of life stages and their morphology in C. bezziana and associated species are given in Spradbery (2002a) and geographical races of C. bezziana are described in Wardhana et al. (2012a).

Eggs: The egg is white, 1.25 mm long and 0.26 mm in diameter with a cylindrical shape, rounded at both ends with the anterior end more tapered. The eggs are laid in a mass of three or more layers thick, glued together in parallel, giving the appearance of a shingled roof.

Larvae: 1st, 2nd and 3rd instar larvae are white to cream coloured 1.6 mm, 3.5-5.5 mm and 6.1-15.7 mm long, respectively, with characteristic bands of spines on most segments. The thorn-like spines are black with a single point. Prominent mouth hooks and heavily sclerotized peritreme surrounding the posterior spiracles with three slit-like openings.

Pupae: Colour changes from deep pink to dark brown as the larval skin changes into the puparium shell through sclerotization. Puparia are characterized by their barrel-shape and retaining many of the external morphological characters of the final stage larva such as spines and spiracles.

Adult fly: The adult fly is 8-12 mm in length and green to blue in colour.

Host Animals

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Animal nameContextLife stageSystem
Bos indicus (zebu)Domesticated host|Wild hostCattle & Buffaloes: All Stages
Bos taurus (cattle)Domesticated host|Wild hostCattle & Buffaloes: All Stages
Bubalus bubalis (Asian water buffalo)Domesticated host|Wild hostCattle & Buffaloes: All Stages
Canis familiaris (dogs)Domesticated host|Wild host:
Capra hircus (goats)Domesticated host|Wild hostSheep & Goats: All Stages
CervidaeWild host:
Elephas maximus:
Gallus gallus domesticusDomesticated hostPoultry: Young poultry|Poultry/Mature female|Poultry/Cockerel|Poultry/Mature male
Homo sapiens:
Loxodonta africana:
Ovis aries (sheep)Domesticated host|Wild hostSheep & Goats: All Stages
Panthera leo (lion):
Sus scrofa (pigs)Domesticated host|Wild hostPigs: All Stages

List of Symptoms/Signs

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General Signs

  • Cyanosis, blue skin or membranes
  • Inability to stand, downer, prostration
  • Swelling mass penis, prepuce, testes, scrotum

Nervous Signs

  • Dullness, depression, lethargy, depressed, lethargic, listless

Pain

  • Discomfort Signs/Skin pain

Reproductive Signs

  • Paraphimosis or priapism, inability to retract penis
  • Phimosis

Skin

  • Integumentary Signs/Alopecia, thinning, shedding, easily epilated, loss of, hair
  • Integumentary Signs/Foul odor skin, smell
  • Integumentary Signs/Parasite visible, skin, hair, feathers
  • Integumentary Signs/Skin erythema, inflammation, redness
  • Integumentary Signs/Skin necrosis, sloughing, gangrene
  • Integumentary Signs/Skin ulcer, erosion, excoriation

Urinary Signs

  • Dysuria, difficult urination, stranguria

Climate

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ClimateStatusDescriptionRemark
A - Tropical/Megathermal climate Preferred Average temp. of coolest month > 18°C, > 1500mm precipitation annually
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Preferred < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Preferred < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
B - Dry (arid and semi-arid) Tolerated < 860mm precipitation annually
C - Temperate/Mesothermal climate Tolerated Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
35 27

Notes on Natural Enemies

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A species of Syrphophagus (Hymenoptera: Encyrtidae), a generalist parasitoid of fly puparia, was accidentally introduced to laboratory cultures of Chrysomya bezziana in Papua New Guinea in 1975 (Spradbery, unpublished observations). No other parasitoids of C. bezziana have been reported. General insect predators such as birds may take adult C. bezziana in the field but no observations have been reported. Rats have been recorded feeding on mature C. bezziana larvae after they dropped from infested cattle (Spradbery, unpublished observations).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Animal productionMovements of infested humans, stock or wildlife Yes Yes Spradbery, 1994

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
AircraftAdults Yes Rajapaksa and Spradbery, 1989
LivestockOWS Larvae via live sheep trade; OWS Adults via returning, empty livestock ships Yes Yes Kloft et al., 1981; Rajapaksa and Spradbery, 1989

Economic Impact

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In Zimbabwe (Rhodesia) Chrysomya bezziana is, with the exception of the tsetse fly, Glossina morsitans, the most important insect pest of cattle, horses, dogs and other domestic animals (Cuthbertson, 1933). When the tick control programme broke down during the 1973-1978 guerilla war in Rhodesia, more than 300,000 livestock were lost, the majority due to C. bezziana infestations (Norval, 1978). C. bezziana is considered a major obstacle to large-scale beef production in Malaysia (Basset and Kadir 1982). The economic impact of the 1996 Iraq incursion included an estimated FAO/AOAD budget at the time of US$8,555,000 to counter the invasion (Spradbery and El-Dessouky, 1998). The cost of a C. bezziana incursion resulting in the establishment of the pest in Australia was estimated as high as $AUD900 million per annum a decade ago (Kwabena Anaman in Spradbery, 2002b). The social impact of livestock production losses is matched by the misery of human infestations caused by C. bezziana, especially among children and the aged and infirm. The adverse impacts on wildlife would also be considerable.

Environmental Impact

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Impact on Habitats

Generally low, if any, measureable adverse impacts on habitat.

Impact on Biodiversity

Because of its wide host range, Chrysomya bezziana is unlikely to have a major impact on biodiversity although, in the United States, the New World Screw-worm fly species killed 80 per cent of fawns of one species of deer, the white-tailed deer (Odocoileus virginianus texanus) in some years (Fuller, 1962). The introduction of livestock breeds naïve for screw-worm fly into endemic areas such as Antipodean sheep to India and Papua New Guinea can be catastrophic for the new arrivals (Basset and Kadir, 1982; Spradbery, unpublished observations).

Risk and Impact Factors

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Impact mechanisms

  • Parasitism (incl. parasitoid)
  • Pathogenic

Impact outcomes

  • Host damage
  • Negatively impacts agriculture
  • Negatively impacts animal health
  • Negatively impacts human health
  • Negatively impacts livelihoods
  • Transportation disruption

Invasiveness

  • Benefits from human association (i.e. it is a human commensal)
  • Capable of securing and ingesting a wide range of food
  • Fast growing
  • Has a broad native range
  • Has high reproductive potential
  • Highly mobile locally
  • Invasive in its native range
  • Is a habitat generalist
  • Proved invasive outside its native range
  • Tolerant of shade

Likelihood of entry/control

  • Difficult/costly to control
  • Highly likely to be transported internationally accidentally

References

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Abdul Rassoul MS; Ali HA; Jassim FA, 1996. Notes on Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), first recorded from Iraq. Bulletin of the Iraq Natural History Museum, 8:113-115.

Al-Izzi MAJ; Al-Taweel AA; Jassim FA, 1999. Epidemiology and rearing of Old World screwworm, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae) in Iraq. Iraqi Journal of Agriculture, 4:153-160.

Animal Health Australia, 2007. Disease Strategy: Screw-worm fly (Version 3). Australian Veterinary Emergency Plan (AUSVETPLAN), Edition 3. Canberra, ACT, Australia: Primary Industries Ministerial Council, 60 pp.

Ansari MA; Oertley RE, 1982. Nasal myiasis due to Bezzi's blowfly (screw worm): case report. Saudi Medical Journal, 3(4):275-278.

Baker JAF; Mchardy WM; Thorburn JA; Thompson GE, 1968. Chrysomya bezziana Villeneuve-some observations on its occurrence and activity in the Eastern Cape Province. South African Veterinary Medical Association, 39:3-11.

Basset CR; Kadir SBA, 1982. The screw-worm fly (Chrysomya bezziana): an obstacle to large-scale beef production in Malaysia. In: Animal production and health in the tropics. Proceedings of the First Asian-Australasian Animal Science Congress, Serdang, 2nd-5th September 1980 [ed. by M.R. Jainudeen\A.R. Omar]. Serdang, Selangor, Malaysia: Universiti Pertanian, 133-135.

Beckett S; Spradbery JP; Urech R; James; P; Green P; Welch M, 2014. Old World Screw-worm Fly: Risk of Entry into Australia and Surveillance Requirements. Report for Animal Health Australia. Canberra, Australia: Animal Health Australia, 192 pp.

Cuthbertson A, 1933. The Habits and Life Histories of some Díptera in Southern Rhodesia. Proceedings and Transactions of the Rhodesia Scientific Association, 32:81-111 pp.

Fuller G, 1962. How screwworm eradication will affect wildlife. The Cattleman, 48:82-84.

Hall MJR; Edge W; Testa JM; Adams ZJO; Ready PD, 2001. Old World screwworm fly, Chrysomya bezziana, occurs as two geographical races. Medical and Veterinary Entomology, 15(4):393-402.

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21/07/15 Original text by:

Dr J. Philip Spradbery, XCS Consulting Pty Ltd, GPO Box 2566, Canberra, ACT 2600, Australia.

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