Resistance and the control of sheep ectoparasites

Levot, G. W.

doi:10.1016/0020-7519(95)00070-i

Cited by 94 publications

(56 citation statements)

References 27 publications

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“…The stable fly and other synanthropic Diptera are nuisance insects that affect the U.S. tourist industry (Merritt et al 1983). In Australia, annual loss of production and treatment costs for the sheep blow fly (Lucilia cuprina), an immigrant ectoparasite responsible for cutaneous myiasis (flystrike) of sheep (Levot 1995), amount to more than AU$160 million (McLeod 1995).…”

Section: Detrimentalmentioning

confidence: 99%

Adventive (Non‐Native) Insects: Importance to Science and Society

Wheeler

Hoebeke

2009

Insect Biodiversity

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Section: Detrimentalmentioning

confidence: 99%

Adventive (Non‐Native) Insects: Importance to Science and Society

Wheeler

Hoebeke

2009

Insect Biodiversity

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“…The major form, called diazinon resistance, now exceeds frequencies of 90% in Australia and New Zealand, with the minor form, called malathion resistance, around 5-10%, and susceptible variants are quite rare (7,8). There is much less information available for L. cuprina populations outside Australasia, many of which are much less exposed to OPs, but bioassay data suggest that populations in South Africa also segregate for at least one of these resistances (6, 9).…”

mentioning

confidence: 99%

Amplification of DNA from preserved specimens shows blowflies were preadapted for the rapid evolution of insecticide resistance

Hartley

Newcomb²,

Russell³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

154

128

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Mutations of esterase 3 confer two forms of organophosphate resistance on contemporary Australasian Lucilia cuprina. One form, called diazinon resistance, is slightly more effective against commonly used insecticides and is now more prevalent than the other form, called malathion resistance. We report here that the single amino acid replacement associated with diazinon resistance and two replacements associated with malathion resistance also occur in esterase 3 in the sibling species Lucilia sericata, suggesting convergent evolution around a finite set of resistance options. We also find parallels between the species in the geographic distributions of the polymorphisms: In both cases, the diazinon-resistance change is absent or rare outside Australasia where insecticide pressure is lower, whereas the changes associated with malathion resistance are widespread. Furthermore, PCR analysis of pinned specimens of Australasian L. cuprina collected before the release of organophosphate insecticides reveals no cases of the diazinonresistance change but several cases of those associated with malathion resistance. Thus, the early outbreak of resistance in this species can be explained by the preexistence of mutant alleles encoding malathion resistance. The pinned specimen analysis also shows much higher genetic diversity at the locus before organophosphate use, suggesting that the subsequent sweep of diazinon resistance in Australasia has compromised the scope for the locus to respond further to the ongoing challenge of the insecticides.Lucilia cuprina ͉ Lucilia sericata ͉ mutation ͉ convergent evolution ͉ organophosphates O ne of the major unresolved issues in our understanding of adaptive evolutionary change is the extent to which the acquisition of newly beneficial traits proceeds by the selection of existing (preadaptive) rare variants, rather than waiting on new mutations to arise once the selection pressure is imposed. These two scenarios could have very different consequences for the nature of the acquired adaptation, its rate of uptake, and the fate of genetic variation in the chromosomal region surrounding the selected locus. Direct evidence discriminating the two possibilities in natural populations of eukaryotes has been lacking because the critical data needed must include samples that have not been exposed to the selection pressure.The phenomenon of insecticide resistance is proving an informative model for studying microevolutionary processes in eukaryotes because it represents a rapid contemporary acquisition of a major new biochemical phenotype and it generally has a relatively simple genetic basis. The rapidity with which resistance often follows the first use of new pesticides has prompted much speculation about preadaptation at the relevant loci (1, 2). However, many cases have also been recorded where resistant genotypes have fitness costs in the absence of insecticide (3, 4), which would seem at odds with the preadaptation hypothesis. In this paper, we present evidence that tests the hypothesis direct...

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“…This is seen particularly clearly in the control of lice (Johnson et al, 1992;James et al, 1993;Levot, 1995;Ellse et al, 2012), mites (Beugnet et al, 1997) and ticks (Foil et al, 2004). In addition, restrictions on the use of some insecticides, such as organochlorines, organophosphates and pyrethroids, because of 234 L. Ellse and R. Wall metabolites are volatile molecules of low molecular weight.…”

Section: Introductionmentioning

confidence: 99%

The use of essential oils in veterinary ectoparasite control: a review

Ellse

Wall

2013

Medical Vet Entomology

120

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There is a growing body of evidence indicating the potential value of essential oils as control agents against a range of arthropod ectoparasites, particularly lice, mites and ticks. Toxicity has been demonstrated following immersion and physical contact with treated surfaces, as well as after exposure to the vapour of these oils; the last of these factors implies that there is a neurotoxic, rather than simply a mechanical, pathway in their mode of action. However, the volatile nature of essential oils suggests that their residual activity is likely to be short-lived. A possible advantage of essential oils over conventional ectoparasite treatments may refer to their reported ovicidal efficacy, although it is unclear whether this results from neurotoxicity or mechanical suffocation. There are many difficulties in comparing the findings of existing studies of essential oil toxicity. One major issue is the wide variation among batches in the relative concentrations of oil constituents. A second issue concerns the fact that many experimental designs make it difficult to confirm that the effect seen is attributable to the oil; in many cases inappropriate controls mean that the effects of the excipient on mortality cannot be distinguished. Hence, it is important that an excipient-only control is always included in these bioassays. Furthermore, in direct contact assays, when attempting to identify the toxicity pathway of the essential oil tested, it is important to include a hydrophobic control. Without this, it is impossible to distinguish simple mechanical effects from neurological or other cellular toxicity. The use of essential oils in the control of veterinary ectoparasites is an area which holds considerable potential for the future and research into their use is still at an early stage. More extensive field trials, the standardization of components, the standardization of extraction, the standardization of good experimental design, mammalian toxicology profiling and excipient development, as well as further investigation into the residual activities and shelf-lives of these oils are all required to allow the full realization of their potential.

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Resistance and the control of sheep ectoparasites

Cited by 94 publications

References 27 publications

Adventive (Non‐Native) Insects: Importance to Science and Society

Adventive (Non‐Native) Insects: Importance to Science and Society

Amplification of DNA from preserved specimens shows blowflies were preadapted for the rapid evolution of insecticide resistance

The use of essential oils in veterinary ectoparasite control: a review

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