Mapping, characterising and targeting acaricide resistance in the poultry red mite, Dermanyssus gallinae.

Atkinson, Abigail A (2019) Mapping, characterising and targeting acaricide resistance in the poultry red mite, Dermanyssus gallinae. Doctoral thesis, Northumbria University.

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Abstract

Dermanyssus gallinae represents a significant threat to poultry production in the UK and control is typically achieved through the use of acaricides, but farmers are facing increasing incidence of pesticide resistance. This must be managed through considered application of acaricides and to facilitate this, a map of D. gallinae perceived resistance has been created, to which future resistance can be compared. Toxicity testing has shown no geographical correlations in resistance, suggesting farms need testing on a per farm basis to provide a best practice recommendation. Additionally, a greater understanding of acaricide detoxification mechanisms is required. Research indicates that functional modification of P450s is responsible for the occurrence of pesticide resistance in many arthropods. In order to characterise resistance mechanisms, transcriptome data has been analysed and a database of putative pesticide metabolising sequences has been created. An attempt to develop a method for microsome preparation from D. gallinae was made for use with Activity Based Probes to identify pesticide metabolising protein sequences in the future. As well as identifying P450s, cytochrome b5 and P450 oxidoreductase required identification. P450 oxidoreductase has been putatively identified using sequence data analysis but not yet successfully isolated. However, cytochrome b5 from D. gallinae along with Rhipicephalus microplus and Ixodes scapularis has been successfully amplified, expressed and purified. A baculovirus expression vector has been created to express D. gallinae cytochrome b5, which showed no effect on pesticide metabolism when amplified alone. A Glutathione S-transferase gene has also been cloned into an expression vector to compare the different mechanisms of metabolism. This will allow future links between D. gallinae genetics and resistance to be established, facilitating real-time tailoring of treatment programmes to ensure maximum efficacy.

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