Elsevier

Veterinary Parasitology

Volume 189, Issue 1, 30 September 2012, Pages 44-51
Veterinary Parasitology

Ovine cutaneous myiasis: Effects on production and control

https://doi.org/10.1016/j.vetpar.2012.03.031Get rights and content

Abstract

Ovine cutaneous myiasis (‘fly strike’) remains a major sheep health problem in many areas of the world. Myiasis risk is the result of a complex interaction of factors, such as fly and host abundance, host susceptibility, climate and, critically, husbandry and management strategies, all of which change seasonally in space and time. Given the complexity of the interacting factors, changes in myiasis incidence are hard to predict, as accordingly are the optimal husbandry responses required to manage the problem. Here the important risk factors are briefly reviewed and the future changes in myiasis incidence under conditions of anticipated climate change are considered. It is concluded that future work should focus in particular on evaluating the optimum use of integrated management, such as the combination of insecticide and trap use, in different environments under a range of farming regimes.

Introduction

At least eighty species of the dipteran families Calliphoridae (blowflies) and Sarcophagidae (fleshflies), belonging largely to the genera Lucilia, Calliphora, Chrysomya, Phormia and Sarcophaga, have been recorded as agents of myiasis (Hall and Wall, 1995). However, two species of facultative blowflies are of particular economic importance in sheep rearing areas of the world: Lucilia sericata and L. cuprina (Foster et al., 1975, Tenquist and Wright, 1976, French et al., 1992, McLeod, 1995, Snoep et al., 2002). This review will provide an overview of their effects on production, potential risk factors and control of the problems primarily caused by these two species, although brief mention will also be made of the obligate sarcophagid, Wohlfahrtia magnifica.

Section snippets

Biology of Lucilia blowflies and sheep myiasis

The species of Lucilia that facultatively parasitise sheep, deposit batches of about 200 eggs in the wool of their ovine host. After hatching from the egg, first stage larvae migrate down the wool fibres to the skin. Feeding is assisted by proteolytic enzymes, which initiate external digestion of the host's tissue and mouth hooks, which abrade the skin surface (Evans, 1936). The mature third stage larvae cease feeding and enter a dispersal phase, in which they migrate away from the lesion, drop

Wohlfahrtia magnifica

Although the focus of this review is primarily on myiasis caused by Lucilia blowflies, some mention must be made of the sarcophagid, W. magnifica, since this species may be of considerable importance in some sheep-rearing areas. It is found throughout the para-Mediterranean basin and in Eastern Europe, extending eastwards into China, including the steppe regions of continental Europe. In these high temperatures and low humidity areas, W. magnifica is usually a more abundant and more clinically

Risk factors

The incidence of ovine cutaneous myiasis by Lucilia blowflies is determined by two groups of factors: those that influence sheep susceptibility and those that affect fly abundance. However, it is often difficult to disentangle the various individual factors that act together to influence the overall pattern risk and of myiasis incidence, particularly because different risk factors affect the localisation of the myiasis on the body or the time of year when it occurs. Furthermore, the importance

Control

Since the incidence of ovine cutaneous myiasis is determined largely by two factors: the number of susceptible sheep and the number of flies available to oviposit, for control two strategies can be considered. These are reducing sheep susceptibility and reducing fly abundance to a level that significantly reduces challenge. These strategies are not necessarily mutually exclusive.

Climate change

Sheep susceptibility, fly abundance and fly activity are, as described above, all strongly influenced by weather conditions. Hence, myiasis incidence would be expected to be highly sensitive to even relatively small changes in climate. In temperate environments, the range of elevated temperatures predicted by current climate change scenarios are likely to result in longer fly activity seasons with earlier spring emergence and a higher cumulative incidence of myiasis leading ultimately, as is

Concluding remarks

Sheep farmers adopt a range of approaches to the type and timing of management used for the control of myiasis, the rational basis for which is often not well evaluated. Selection of the most appropriate management strategy, particularly in relation to insecticide application, is important, because it will help to minimise disease incidence relative to cost, while also helping to reduce the potential for insecticide resistance development. In seasonal environments, where fly abundance increases

Conflict of interest statement

The author has no conflicts of interest that may have unduly affected the views expressed in this review.

References (102)

  • R.S. McLeod

    Costs of major parasites to the Australian livestock industries

    Int. J. Parasitol.

    (1995)
  • S. Rehbein et al.

    Evaluation of the anthelmintic efficacy of an ivermectin controlled-release capsule in lambs under field conditions in Europe

    Small Rumin. Res.

    (1999)
  • R.M. Sandeman

    Prospects for the control of sheep blowfly by vaccination

    Int. J. Parasitol.

    (1990)
  • H.R. Schmid et al.

    Field efficacy of the insect growth regulator dicyclanil for flystrike prevention on lambs

    Vet. Parasitol.

    (1999)
  • J.J. Snoep et al.

    Myiasis in sheep in the Netherlands

    Vet. Parasitol.

    (2002)
  • J. Stevens et al.

    The evolution of ectoparasitism in the genus Lucilia (Diptera: Calliphoridae)

    Int. J. Parasitol.

    (1997)
  • J.R. Stevens et al.

    The evolution of myiasis in man and animals in the Old and New Worlds

    Trends Parasitol.

    (2006)
  • R.L. Tellam et al.

    Control of blowfly strike in sheep: current strategies and future prospects

    Int. J. Parasitol.

    (1997)
  • C. Townend

    Sheep strike and mulesing

    Parasitol. Today

    (1987)
  • R. Wall

    The reproductive output of the blowfly Lucilia sericata

    J. Insect Physiol.

    (1993)
  • M.P. Ward

    Effectiveness of a synthetic lure to reduce blowfly strike incidence: preliminary observations

    Vet. Parasitol.

    (2001)
  • M.P. Ward et al.

    Sheep blowfly strike reduction using a synthetic lure system

    Prev. Vet. Med.

    (2003)
  • G.R. Allerton et al.

    Field trials evaluating ivermectin controlled-release capsules for weaner sheep and breeding ewes

    Aust. Vet. J.

    (1998)
  • J.M.E. Anderson et al.

    Trapping sheep blowflies using bait-bins

    Aust. Vet. J.

    (1990)
  • J.R. Ashworth et al.

    Responses of the sheep blowflies Lucilia sericata and L. cuprina to odour and the development of semiochemical baits

    Med. Vet. Entomol.

    (1994)
  • P.G. Bates

    Therapies for ectoparasitism in sheep

    In Pract.

    (2004)
  • R. Bennett et al.

    Economic assessment of livestock diseases in Great Britain

    Final Report to the Department for Environment, Food and Rural Affairs

    (2003)
  • B. Bisdorff et al.

    Prevalence and regional distribution of scab, lice and blowfly strike in sheep in Great Britain

    Vet. Rec.

    (2006)
  • B. Bisdorff et al.

    Sheep blowfly strike risk management in Great Britain: a survey of current practice

    Med. Vet. Entomol.

    (2008)
  • A. Brinkmann

    Blowfly myiasis of sheep in Norway

    Norw. J. Zool.

    (1976)
  • M. Broadmeadow et al.

    The pathogenesis of flystrike in sheep

    Wool Technol. Sheep Breed.

    (1984)
  • J.M. Broughan et al.

    Fly abundance and climate as determinants of sheep blowfly strike incidence

    Med. Vet. Entomol.

    (2007)
  • D.J. Cooper et al.

    Bacterial pathogens of the Australian sheep blowfly Lucilia cuprina

  • R. Dallwitz et al.

    Factors determining the predominance of Lucilia cuprina larvae in blowfly strikes of sheep in southern New South Wales

    J. Aust. Entomol. Soc.

    (1984)
  • J.J. Dymock et al.

    Habitat preferences and carcase colonization by sheep blowflies in the northern North Island of New Zealand

    Med. Vet. Entomol.

    (1993)
  • J.J. Dymock et al.

    Large-scale trapping of sheep blowflies in the Northern North-Island of New Zealand using insecticide-free traps

    Aust. J. Exp. Agric.

    (1995)
  • J.P.J. Eerens et al.

    Influence of the rye grass endophyte (Neotyphodium lolii) in a cool moist environment. II. Sheep Production 4

    N. Z. J. Agric. Res.

    (1998)
  • A.C. Evans

    The physiology of the sheep blowfly Lucilia sericata (Meigen)

    Trans. R. Entomol. Soc.

    (1936)
  • G.G. Foster et al.

    Sheep blowfly and its control: in the pastoral ecosystem in Australia

    Proc. Ecol. Soc. Aust.

    (1975)
  • I.A. Fragkou et al.

    Observations in ovine myiasis in Greece, with special reference to clinical findings and therapeutic considerations

  • N.P. French et al.

    Role of neonatal and maternal risk factors in the faecal soiling of lambs

    Vet. Rec.

    (1996)
  • N.P. French et al.

    Prevalence, regional distribution and control of blowfly strike in England and Wales

    Vet. Rec.

    (1992)
  • N. French et al.

    Blowfly strike in England and Wales: the relationship between prevalence and farm and management factors

    Med. Vet. Entomol.

    (1994)
  • N.P. French et al.

    Lamb tail docking: a controlled field study of the effects of tail amputation on health and productivity

    Vet. Rec.

    (1994)
  • N.P. French et al.

    Ectoparasite control on sheep farms in England and Wales: the method, type and timing of insecticidal treatment

    Vet. Rec.

    (1994)
  • N.P. French et al.

    The seasonal pattern of sheep blowfly strike in England and Wales

    Med. Vet. Entomol.

    (1995)
  • S.G. Gherardi et al.

    The association between body strike and dermatophilosis of sheep under controlled conditions

    Aust. Vet. J.

    (1981)
  • V.H. Guerrini

    Ammonia toxicity and alkalosis in sheep infested by Lucilia cuprina larvae

    Int. J. Parasitol.

    (1988)
  • M.J.R. Hall

    Traumatic myiasis of sheep in Europe: a review

    Parassitologia

    (1997)
  • M.J.R. Hall et al.

    Traumatic myiasis of humans and animals

  • Cited by (0)

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