Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Cochliomyia hominivorax
(New World screwworm)

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Datasheet

Cochliomyia hominivorax (New World screwworm)

Summary

  • Last modified
  • 04 May 2018
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Cochliomyia hominivorax
  • Preferred Common Name
  • New World screwworm
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta
  • Summary of Invasiveness
  • Cochliomyia hominivorax (Coquerel) is endemic to the Western Hemisphere, with the exception of Chile., although it has been eradicated from significant parts of its range. Although naturally occurring in relati...

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Pictures

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PictureTitleCaptionCopyright
Screwworm - Screwworm myiasis in a calf navel.
TitleExternal symptoms
CaptionScrewworm - Screwworm myiasis in a calf navel.
Copyright©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Screwworm - Screwworm myiasis in a calf navel.
External symptomsScrewworm - Screwworm myiasis in a calf navel.©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Adult female screwworm fly.
TitleAdult
CaptionAdult female screwworm fly.
Copyright©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Adult female screwworm fly.
AdultAdult female screwworm fly.©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Screwworm. Third instar larvae of Cochliomyia hominivorax.
TitleScrewworm larvae
CaptionScrewworm. Third instar larvae of Cochliomyia hominivorax.
Copyright©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Screwworm. Third instar larvae of Cochliomyia hominivorax.
Screwworm larvaeScrewworm. Third instar larvae of Cochliomyia hominivorax.©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)

Identity

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Preferred Scientific Name

  • Cochliomyia hominivorax Coquerel

Preferred Common Name

  • New World screwworm

Other Scientific Names

  • Calliphora hominivorax (COQUEREL)
  • Callitroga americana (CUSHING & PATTON)
  • Callitroga hominivorax
  • Cochliomyia americana
  • Lucilia hominivorax

International Common Names

  • English: flies, screwworm; Primary screwworm; screw worm; screwworm; screwworms in livestock
  • Spanish: Gusano Barrenador del Ganado
  • French: lucilie bouchere; ver en vis
  • Portuguese: bicheira

Local Common Names

  • Aruba: Schroefworm
  • Germany: Fliege, Schraubenwurm-
  • Netherlands Antilles: Schroefworm

EPPO code

  • COCLAM (Cochliomyia americana)
  • COCLHO (Cochliomyia hominivorax)

Summary of Invasiveness

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Cochliomyia hominivorax (Coquerel) is endemic to the Western Hemisphere, with the exception of Chile., although it has been eradicated from significant parts of its range. Although naturally occurring in relatively low numbers compared with other insect species, C. hominivorax has been introduced and spread into non-endemic and eradicated areas via movement of infested hosts, including humans. Introductions of C. hominivorax, sometimes resulting in outbreaks, have occurred in the United States of America, Mexico, Panama, Curacao, Aruba, Libya, and Australia.

Taxonomic Tree

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

Notes on Taxonomy and Nomenclature

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The taxonomy and nomenclature of this species was very confused for over 100 years. Cushing and Patton (1933) documented the difference between Cochliomyia americana C & P and Cochliomyia macellaria Fabricius, which served as a key basis in the eradication of Cochliomyia hominivorax from North America, Central America and parts of the Caribbean. Dear (1985) presents an explanation of the taxonomy and nomenclature of C. hominivorax and other members of the Chrysomyini.

Distribution

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Cochliomyia hominivorax is endemic to the Western Hemisphere and occurs in tropical, subtropical, and temperate zones. Northern and southern limits of its range are primarily due to cold weather. Cochliomyia hominivorax is present in all South American countries with the exception of Chile. This species is also present in Cuba, the Dominican Republic, Haiti, Jamaica, and Trinidad and Tobago. Cochliomyia hominivorax has been eradicated from the United States of America, Mexico, Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama (an outbreak in Florida in 2016 was eradicated in 2017). A barrier zone is maintained in Panama using sterile flies and field operations to prevent immigration of C. hominivorax into eradicated areas. Eradication has also been achieved in Curacao, Netherlands Antilles, British Virgin Islands, US Virgin Islands, and Puerto Rico.

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

AfghanistanNo information availableOIE, 2009
ArmeniaDisease not reportedOIE, 2009
AzerbaijanDisease not reportedOIE, 2009
BahrainDisease never reportedOIE, 2009
BangladeshDisease never reportedOIE, 2009
BhutanDisease never reportedOIE, 2009
Brunei DarussalamNo information availableOIE Handistatus, 2005
CambodiaNo information availableOIE, 2009
ChinaDisease never reportedOIE, 2009
-Hong KongNo information availableOIE, 2009
Georgia (Republic of)Disease never reportedOIE Handistatus, 2005
IndiaDisease never reportedOIE, 2009
IndonesiaDisease not reportedOIE, 2009
IranDisease never reportedOIE, 2009
IraqDisease never reportedOIE, 2009
IsraelDisease never reportedOIE, 2009
JapanNo information availableOIE, 2009
JordanDisease never reportedOIE, 2009
KazakhstanDisease never reportedOIE, 2009
Korea, DPRDisease not reportedOIE Handistatus, 2005
Korea, Republic ofDisease never reportedOIE, 2009
KuwaitDisease never reportedOIE, 2009
KyrgyzstanDisease never reportedOIE, 2009
LaosDisease never reportedOIE, 2009
LebanonDisease never reportedOIE, 2009
MalaysiaDisease never reportedOIE, 2009
-Peninsular MalaysiaDisease not reportedOIE Handistatus, 2005
-SabahDisease never reportedOIE Handistatus, 2005
-SarawakDisease never reportedOIE Handistatus, 2005
MongoliaNo information availableOIE, 2009
MyanmarDisease never reportedOIE, 2009
NepalNo information availableOIE, 2009
OmanDisease never reportedOIE, 2009
PakistanDisease not reportedOIE, 2009
PhilippinesNo information availableOIE, 2009
QatarNo information availableOIE, 2009
Saudi ArabiaDisease never reportedOIE, 2009
SingaporeDisease never reportedOIE, 2009
Sri LankaDisease never reportedOIE, 2009
SyriaDisease not reportedOIE, 2009
TaiwanDisease never reportedOIE Handistatus, 2005
TajikistanDisease never reportedOIE, 2009
ThailandNo information availableOIE, 2009
TurkeyDisease never reportedOIE, 2009
TurkmenistanDisease not reportedOIE Handistatus, 2005
United Arab EmiratesDisease never reportedOIE, 2009
UzbekistanDisease never reportedOIE Handistatus, 2005
VietnamDisease never reportedOIE, 2009
YemenNo information availableOIE, 2009

Africa

AlgeriaDisease never reportedOIE, 2009
AngolaDisease never reportedOIE, 2009
BeninNo information availableOIE, 2009
BotswanaDisease not reportedOIE, 2009
Burkina FasoNo information availableOIE, 2009
BurundiDisease never reportedOIE Handistatus, 2005
CameroonDisease never reportedOIE Handistatus, 2005
Cape VerdeNo information availableOIE Handistatus, 2005
Central African RepublicDisease not reportedOIE Handistatus, 2005
ChadNo information availableOIE, 2009
CongoNo information availableOIE, 2009
Congo Democratic RepublicDisease not reportedOIE Handistatus, 2005
Côte d'IvoireDisease not reportedOIE Handistatus, 2005
DjiboutiDisease never reportedOIE, 2009
EgyptDisease never reportedOIE, 2009
EritreaNo information availableOIE, 2009
EthiopiaDisease never reportedOIE, 2009
GabonNo information availableOIE, 2009
GambiaNo information availableOIE, 2009
GhanaNo information availableOIE, 2009
GuineaNo information availableOIE, 2009
Guinea-BissauNo information availableOIE, 2009
KenyaDisease never reportedOIE, 2009
LesothoDisease never reportedOIE, 2009
LibyaLast reported1991FAO, 1992; OIE Handistatus, 2005
MadagascarDisease never reportedOIE, 2009
MalawiNo information availableOIE, 2009
MaliNo information availableOIE, 2009
MauritiusDisease never reportedOIE, 2009
MoroccoDisease never reportedOIE, 2009
MozambiqueDisease never reportedOIE, 2009
NamibiaNo information availableOIE, 2009
NigeriaDisease never reportedOIE, 2009
RéunionNo information availableOIE Handistatus, 2005
RwandaDisease never reportedOIE, 2009
Sao Tome and PrincipeDisease not reportedOIE Handistatus, 2005
SenegalNo information availableOIE, 2009
SeychellesDisease not reportedOIE Handistatus, 2005
SomaliaNo information availableOIE Handistatus, 2005
South AfricaDisease never reportedOIE, 2009
SudanDisease never reportedOIE, 2009
SwazilandNo information availableOIE, 2009
TanzaniaNo information availableOIE, 2009
TogoNo information availableOIE, 2009
TunisiaDisease never reportedOIE, 2009
UgandaNo information availableOIE, 2009
ZambiaDisease never reportedOIE, 2009
ZimbabweDisease never reportedOIE, 2009

North America

BermudaDisease not reportedOIE Handistatus, 2005
CanadaDisease never reportedOIE, 2009
GreenlandDisease never reportedOIE, 2009
MexicoEradicated1991Wyss, 2000; OIE, 2009
USAEradicated1966Wyss, 2000; OIE, 2009
-FloridaEradicated2017Introduced1933 Invasive Skoda et al., 2018Originally introduced in 1930s; eradicated by 1959; outbreak in 2016 eradicated in 2017

Central America and Caribbean

BarbadosDisease never reportedOIE Handistatus, 2005
BelizeEradicated1994Wyss, 2000; OIE, 2009
British Virgin IslandsEradicated1975Wyss, 2000; OIE Handistatus, 2005
CaribbeanPresentCAB ABSTRACTS Data Mining 2001
Cayman IslandsDisease not reportedOIE Handistatus, 2005
Costa RicaEradicated2000Wyss, 2000; OIE, 2009
CubaPresentOIE, 2009
CuraçaoEradicated1954Wyss, 2000; OIE Handistatus, 2005
DominicaDisease not reportedOIE Handistatus, 2005
Dominican RepublicPresentOIE, 2009
El SalvadorPresentWyss, 2000; OIE, 2009
GuadeloupeDisease never reportedOIE, 2009
GuatemalaEradicated1994Wyss, 2000; OIE, 2009
HaitiPresentOIE, 2009
HondurasEradicated1996Wyss, 2000; OIE, 2009
JamaicaPresentOIE, 2009
MartiniqueNo information availableOIE, 2009
Netherlands AntillesEradicated1954CAB ABSTRACTS Data Mining 2001; Wyss, 2000
NicaraguaEradicated1999Wyss, 2000; OIE, 2009
PanamaDisease not reportedUS Federal Register, 2008; OIE, 2009
Puerto RicoEradicated1975Wyss, 2000
Saint Kitts and NevisDisease never reportedOIE Handistatus, 2005
Saint Vincent and the GrenadinesDisease never reportedOIE Handistatus, 2005
Trinidad and TobagoReported present or known to be presentOIE Handistatus, 2005
United States Virgin IslandsEradicated1975CAB ABSTRACTS Data Mining 2001; Williams et al., 1977

South America

ArgentinaPresentOIE, 2009
BoliviaAbsent, reported but not confirmedOIE, 2009
BrazilPresentOIE, 2009
-Mato Grosso do SulPresentCAB ABSTRACTS Data Mining 2001
-Minas GeraisPresentCAB ABSTRACTS Data Mining 2001
-Rio de JaneiroPresentCAB ABSTRACTS Data Mining 2001
-Rio Grande do SulPresentCAB ABSTRACTS Data Mining 2001
-Sao PauloPresentCAB ABSTRACTS Data Mining 2001
ChileDisease never reportedOIE, 2009
ColombiaWidespreadForero et al., 2008; OIE, 2009
EcuadorRestricted distributionOIE, 2009
Falkland IslandsDisease never reportedOIE Handistatus, 2005
French GuianaDisease not reportedOIE, 2009
GuyanaWidespreadGrant et al., 2000
ParaguayReported present or known to be presentOIE Handistatus, 2005
PeruAbsent, reported but not confirmedOIE, 2009
SurinameWidespreadGrant et al., 2000
UruguayPresentOIE, 2009
VenezuelaWidespreadCoronado and Kowalski, 2009; OIE, 2009

Europe

AlbaniaDisease never reportedOIE, 2009
AndorraDisease never reportedOIE Handistatus, 2005
AustriaNo information availableOIE, 2009
BelarusNo information availableOIE, 2009
BelgiumDisease not reportedOIE, 2009
Bosnia-HercegovinaDisease not reportedOIE Handistatus, 2005
BulgariaDisease never reportedOIE, 2009
CroatiaDisease never reportedOIE, 2009
CyprusDisease never reportedOIE, 2009
Czech RepublicDisease never reportedOIE, 2009
DenmarkDisease never reportedOIE, 2009
EstoniaDisease never reportedOIE, 2009
FinlandDisease never reportedOIE, 2009
FranceDisease never reportedOIE, 2009
GermanyDisease never reportedOIE, 2009
GreeceDisease never reportedOIE, 2009
HungaryDisease never reportedOIE, 2009
IcelandDisease never reportedOIE, 2009
IrelandDisease never reportedOIE, 2009
Isle of Man (UK)Disease never reportedOIE Handistatus, 2005
ItalyDisease never reportedOIE, 2009
JerseyDisease never reportedOIE Handistatus, 2005
LatviaDisease never reportedOIE, 2009
LiechtensteinDisease not reportedOIE, 2009
LithuaniaDisease never reportedOIE, 2009
LuxembourgDisease never reportedOIE, 2009
MacedoniaDisease never reportedOIE, 2009
MaltaDisease never reportedOIE, 2009
MoldovaDisease never reportedOIE Handistatus, 2005
MontenegroDisease never reportedOIE, 2009
NetherlandsDisease never reportedOIE, 2009
NorwayDisease never reportedOIE, 2009
PolandDisease never reportedOIE, 2009
PortugalDisease never reportedOIE, 2009
RomaniaNo information availableOIE, 2009
Russian FederationDisease never reportedOIE, 2009
SerbiaDisease never reportedOIE, 2009
SlovakiaDisease never reportedOIE, 2009
SloveniaDisease never reportedOIE, 2009
SpainDisease never reportedOIE, 2009
SwedenDisease never reportedOIE, 2009
SwitzerlandDisease never reportedOIE, 2009
UKDisease never reportedOIE, 2009
-Northern IrelandDisease never reportedOIE Handistatus, 2005
UkraineDisease never reportedOIE, 2009
Yugoslavia (former)No information availableOIE Handistatus, 2005
Yugoslavia (Serbia and Montenegro)Disease never reportedOIE Handistatus, 2005

Oceania

AustraliaDisease never reportedOIE, 2009
French PolynesiaDisease never reportedOIE, 2009
New CaledoniaDisease never reportedOIE, 2009
New ZealandDisease never reportedOIE, 2009
SamoaDisease never reportedOIE Handistatus, 2005
VanuatuDisease never reportedOIE Handistatus, 2005
Wallis and Futuna IslandsNo information availableOIE Handistatus, 2005

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Aruba 2004 Yes No Eradicated 2004; JB Welch, USDA, unpublished data
Aruba 2011 Yes No Eradicated 2011; JB Welch, USDA, unpublished data
Curaçao 1971-1977 Yes No Baumhover (1997) Eradicated 1977
Libya 1988-1992 Animal production (pathway cause) Yes No FAO (1992) Eradicated 1992
Mexico 1992 Yes No Wyss (2000) Eradicated 1992
Mexico 1993 No No Wyss (2000) Eradicated 1993
Mexico 2001 Yes No Eradicated 2001; JB Welch, USDA, unpublished data
Mexico Mexico 2003 No No Introduced due to irradiator malfunction; eradicated 2003; JB Welch, USDA, unpublished data
Panama Mexico 2003 No No Introduced due to irradiator malfunction; eradicated 2003; JB Welch, USDA, unpublished data
Panama 2012 No No Eradicated 2012; JB Welch, USDA, unpublished data
Panama 2009 Yes No Eradicated 2009; C Duerr, COPEG, unpublished data
Florida 2016 No No Skoda et al. (2018) Eradicated 2017

Risk of Introduction

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Risk of introduction of C. hominivorax may be relatively low; however, movement of infested hosts into non-infested habitats remains a risk. As long as populations of C. hominivorax exist in the Western Hemisphere, modern travel conveyances, especially aircraft, make the introduction of C. hominivorax continents away from the original source of infestation a real possibility. Adults of C. hominivorax can occasionally enter cars, boats, ships, and aircraft, but this is extremely rare.

Pathogen Characteristics

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Detailed descriptions of the life stages of C. hominivorax are presented in Laake et al. (1936).

Eggs: Eggs are bright white, approximately 1.04 mm long and 0.26 mm in diameter with a cylindrical shape, rounded at the posterior end and flattened at the anterior end with a dorsal seam extending from the anterior end almost to the posterior end of the egg. Eggs are laid in a parallel pattern in layers glued together to form a mass which gives them the appearance of a shingled roof. Eggs are laid in masses which contain from 10 to 400. Eggs are generally laid on or near the edges of wounds but may also be laid on or near host body orifices with purulent discharge. Eggs have also been observed laid approximately 5 cm from the edge of wounds under the moist wool of sheep in Costa Rica during the rainy season (J Welch, personal observation).

Larvae: First instar larvae are approximately 1.2 mm and 0.23 mm, length and diameter, respectively, at hatching and are clear with internal structures visible. Mature first instar larvae are approximately 3.6 mm and 0.57 mm, length and diameter, respectively, and are whitish in colour. Newly molted second instar larvae are generally whitish in colour and are approximately 3.5mm and 0.6mm, length and diameter, respectively. Mature second instar larvae are approximately 6.3 mm to 7.4 mm and 1.5 mm, length and diameter, respectively, and are whitish to cream coloured. Third instar larvae are white to cream to pink coloured depending on diet, and are approximately 6.4 mm to 17 mm in length and 1.6 mm to 3.5 mm in diameter. All larval instars have characteristic bands of spines on most segments and a pair of heavily sclerotized mouth hooks, main tracheal trunks and spiracles. The spiracles with three slit-like openings are almost completely surrounded by heavily sclerotized peritremes, but which appear incomplete ventrally.

Pupae: Pupae are barrel-shaped and dark brown in colour. They are approximately 10.2 mm and 4.3 mm in length and width, respectively.

Adults:Laake (1936) reported that flies are generally deep metallic greenish-blue in colour. Colour is variable, ranging from metallic light to dark green, light grayish-blue through sky-blue to dark blue (J Welch, personal observation). Flies have three dark longitudinal stripes on the dorsal part of the thorax. C. hominivorax adults are approximately 2-3 times the size of a house fly.

List of Symptoms/Signs

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SignLife StagesType
General Signs / Cyanosis, blue skin or membranes Sign
General Signs / Inability to stand, downer, prostration Sign
General Signs / Swelling mass penis, prepuce, testes, scrotum Sign
Nervous Signs / Dullness, depression, lethargy, depressed, lethargic, listless Sign
Pain / Discomfort Signs / Skin pain Sign
Reproductive Signs / Paraphimosis or priapism, inability to retract penis Sign
Reproductive Signs / Phimosis Sign
Skin / Integumentary Signs / Alopecia, thinning, shedding, easily epilated, loss of, hair Sign
Skin / Integumentary Signs / Foul odor skin, smell Sign
Skin / Integumentary Signs / Parasite visible, skin, hair, feathers Sign
Skin / Integumentary Signs / Skin erythema, inflammation, redness Sign
Skin / Integumentary Signs / Skin necrosis, sloughing, gangrene Sign
Skin / Integumentary Signs / Skin ulcer, erosion, excoriation Sign
Urinary Signs / Dysuria, difficult urination, stranguria Sign

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 Tolerated < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Tolerated < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
C - Temperate/Mesothermal climate Tolerated Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Tolerated Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
41°58’ 38°03’

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -6.67
Mean annual temperature (ºC) 19.4
Mean minimum temperature of coldest month (ºC) 9.4

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall152mm; lower/upper limits

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Araneae Predator Adults not specific
Eriophora ravilla Predator
Formicidae Predator Larvae not specific
Macrocheles muscaedomesticae Parasite
Neoscona oaxacensis Predator
Nephila clavipes Predator
Trichotrombidium muscarum Parasite

Notes on Natural Enemies

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Cochliomyia hominivorax occurs in relatively low numbers compared with other insect species. Populations are aggregated yet mobile within favourable habitats. As a result, no natural enemies specific for C. hominivorax have been identified. Other insects, birds, frogs, lizards and spiders feed on adult C. hominivorax.Welch (1993) describes the predation of ground-released sterile C. hominivorax flies by spiders. Ants (especially Solenopsis sp.) are common predators of larvae that have exited wounds to pupate and have been observed pulling larvae from wounds (J Welch, unpublished data). There are no data to suggest that natural enemies are important to the population dynamics of C. hominivorax.

Economic Impact

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Myiasis by C. hominivorax results in a negative economic impact by a decrease in animal weights and milk production, and an increase in animal death. Additionally increase in the costs of inspection and handling of animals, and the increase in costs of insecticides, and veterinary services and medicines results in a negative economic impact (Wyss, 2000). Wyss (2000) reported substantial annual economic benefits to producers (US$ with conversion to 2015 US$ in parentheses) after eradication of C. hominivorax; $896.1 million ($1.25 billion) for the United States of America, $328.6 ($458.5) million for Mexico, and $87.8 ($122.5) million for all of the Central America countries combined. Expanding the analysis of the economic impact of eradicating C. hominivorax from Central America by adding linkages to the economy and consumer benefits resulted in an estimated total annual economic impact of $704.3 ($982.6) million to consumers (Wyss, 2000). Wyss (2002) estimated the annual economic benefits to producers in South America as $2.8 ($3.91) billion.

Environmental Impact

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Impact on habitats is none or unknown.

Impact on biodiversity is low, but may become more important in localized areas during conditions which promote the increase of C. hominivorax populations. Fuller (1962) reported that mortality of fawns of White-tailed deer, Odocoileus virginianus (Zimmerman), ranged from 20 to 80 percent annually depending on environmental and population conditions.

Social Impact

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Infestation of humans is under-reported due to the negative social implications. Those humans who cannot take care of themselves are especially vulnerable. Although the young, old, and mentally challenged are more susceptible to myiasis, all humans are potential hosts. Humans living in areas of favorable habitats for C. hominivorax are at a higher risk than those living in unfavorable habitats.

Risk and Impact Factors

Top of page Invasiveness
  • Invasive in its native range
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Pioneering in disturbed areas
  • Tolerant of shade
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
  • Benefits from human association (i.e. it is a human commensal)
  • Fast growing
  • Has high reproductive potential
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Host damage
  • Increases vulnerability to invasions
  • Negatively impacts agriculture
  • Negatively impacts cultural/traditional practices
  • Negatively impacts human health
  • Negatively impacts animal health
  • Negatively impacts livelihoods
  • Reduced amenity values
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
  • Damages animal/plant products
  • Negatively impacts trade/international relations
Impact mechanisms
  • Parasitism (incl. parasitoid)
  • Pathogenic
  • Rapid growth
Likelihood of entry/control
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Gaps in Knowledge/Research Needs

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Research is needed on:

1.     Population dynamics and distribution of C. hominivorax in the Amazon Basin.

2.     Development of an attractant for male C. hominivorax.

3.     Development of a new wound-treatment as coumaphos is no longer being produced.

References

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Baumhover AH, 1963. Susceptibility of screwworm larvae and prepupae to dessication. Journal of Economic Entomology, 56:473-475.

Baumhover AH, 1997. A personal account of programs to eradicate the screwworm, Cochliomyia hominivorax, in the United States and Mexico with special emphasis on the Florida program. Pioneer lecture presentation by the Florida Entomological Society, Daytona Beach, Florida, 4 August 1997. 52 pp.

Coquerel C, 1858. Des larves de diptéres developpés dans le sinus frontause et les fossess nasals de l'homme á Cayenne. Archives Genérales Médecines, 5:513-528.

Coronado A, Kowalski A, 2009. Current status of the New World screwworm Cochliomyia hominivorax in Venezuela. Medical and Veterinary Entomology, 23(s1):106-110. http://www.blackwell-synergy.com/loi/mve

Cushing EC, Patton WS, 1933, 20th December. Studies on the Higher Diptera of 134 Medical and Veterinary Importance. Cochliomyia americana sp. nov., the Screw-worm Fly of the New World. Ann. Trop. Med. Parasit, 27(4):539-551 pp.

Dear JP, 1985. A revision of the New World Chrysomyini (Diptera: Calliphoridae). Revista Brasileira de Zoologia, 3(3):109-169.

FAO, 1992. The new world screwworm eradication programme North Africa 1988-1992. Rome, Italy: FAO, 192 pp.

Forero B E, Cortés V J, Villamil J L, 2008. The problem of screwworm, Cochliomyia hominivorax (Coquerel, 1858), in Colombia. (Problemática del gusano barrenador del Ganado, Cochliomyia hominivorax (Coquerel, 1858) en Colombia.) Revista MVZ Cordoba, 13(2):1400-1414. http://apps.unicordoba.edu.co/revistas/revistamvz/mvz-132/v13n2a16.pdf

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

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Links to Websites

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WebsiteURLComment
COPEG, Panama–United States Commission for the Eradication and Prevention of Screwwormhttp://www.copeg.org/
Food and Agriculture Organization of the United Nationshttp://www.fao.org/
IAEA, International Atomic Energy Agencyhttp://www.iaea.org/
US Dept of Agriculture - APHIShttp://www.aphis.usda.gov/
World Organisation for Animal Health (OIE)http://www.oie.intWebsite of the World Organisation for Animal Health (formerly Office International des Epizooties).

Organizations

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World: OIE (World Organisation for Animal Health), 12, rue de Prony, 75017 Paris, France, http://www.oie.int/

Panama: COPEG (Panama-United States Commission for the Eradication and Prevention of Screwworm), http://www.copeg.org/

Austria: IAEA (International Atomic Energy Agency), Vienna International Centre, PO Box 100, A-1400 Vienna, http://www.iaea.org/

Italy: FAO (Food and Agriculture Organization of the United Nations), Viale delle Terme di Caracalla, 00100 Rome, http://www.fao.org/

USA: USDA-APHIS (Animal and Plant Health Inspection Service), US Department of Agriculture 1400, Independence Ave., SW Washington, DC 20250, Washington, DC, USA, http://www.aphis.usda.gov/

Contributors

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27/01/16 Original text by:

John B. Welch, USDA-APHIS-IS, USDA-ARS-SPARC, 2881 F&B Road, College Station, Texas, USA

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