Emyr Davies

Senior Research Scientist - Molecular Entomology
Biointeractions and Crop Protection

Dr T.G.E. Davies, PhD, FRES

Principal Research Scientist, Pesticide Resistance Group, Fellow of the Royal Entomological Society


Dr Emyr Davies joined the Membrane transport group within the Biochemistry and Physiology Department at Rothamsted in 1990, after completing a PhD on senescence in graminaceous species at IGER. During the period 1990-1992 he developed a new and innovative research programme aimed at identifying genes involved in the control of vacuole formation in plants. A successful collaboration with Karl Oparka (SCRI) resulted in important new developments in understanding the mechanisms of uptake of fluorescent dyes into plant cells. In 1992 working alongside Dr Brian Forde he initiated a new project aimed at isolating ATP-Binding Cassette (or ABC) transporters and went on to successfully clone one of the first ABC transporters to be discovered in plants. In 1995 he moved into the Plant Defence Metabolism group to develop the work on herbicide resistance. During this period he formulated ideas about the possible role of MRPs (also members of the ABC superfamily) in glutathione-mediated transport of xenobiotics (including herbicide metabolites) in plants. In late 1996 he returned to work within the Membrane transport group on the molecular characterisation of vacuolar pyrophosphatases. Soon after he joined the newly formed Nutrient Acquisition group, characterizing phosphate uptake and phosphate transport in cereal crops.

Current Research

Research since 2001 has been focused on understanding the molecular basis of target site (voltage-gated sodium channel) resistance to pyrethroids and DDT in agricultural pests and vectors of human disease. Highlights include the identification of the binding site for pyrethroids and DDT, the identification of key amino acid differences within the binding site responsible for the acaricidal specificity of some pyrethroids, a re-investigation of the mechanism underlying pyrethroid resistance in Varroa destructor, an ectoparasitic mite affecting honeybees and the isolation and characterization of the malarial mosquito and aphid sodium channels. The aphid sodium channel is of particular interest as it was found that aphids have an atypical channel. Since 2009 he has also worked on insect ryanodine receptors, which are the molecular targets of the new insecticides flubendiamide and rynaxypyr. In 2012, in a unique collaboration with Bayer CropScience and Syngenta Crop Protection, the first reported mutation (G4946E) in the RyR gene associated with a high level of resistance to both classes of diamide insecticides was identified in P. xylostella. More recently his research group have been exploiting advances in genome editing based on CRISPRs to make targeted changes in insect genomes and assess the effect on their phenotypes.

 Further information:  Researchgate profile / Linkedin profile / ResearcherID / ORCID


He also currently manages a DEFRA-approved testing facility at Rothamsted for evaluating the effectiveness of crop protection products on a wide range of invertebrate pest species. The facility also provides an interface with the agro-chemical industry and also with commercial growers where invertebrate pest issues can be identified and discussed. - See more at

Outside collaborators:

Prof Bonnie Wallace (Professor of Molecular Biophysics / Director CPMSD Daresbury), Dept of Crystallography, Birkbeck College, London.

Dr Andrias O'Reilly (Senior Lecture in Neurobiology), School of Natural Sciences and Psychology, Liverpool John Moores University

Prof Allan Williams (BHF Chair of Cardiovascular Science), Cardiff University School of Medicine.

Dr Christopher George (Reader),  Cardiff University School of Medicine

Dr Ian Duce (Associate Prof) and Dr Ian Mellor (Lecturer), Molecular Cell Biology and Biophysics Group, University of Nottingham.

Dr Melanie Scharway, Bayer CropScience AG. Alfred-Nobel-Str. 50. 40789 Monheim. Germany.

Dr Ralf Nauen (Research Fellow Resistance Management), Bayer CropScience AG. Alfred-Nobel-Str. 50. 40789 Monheim. Germany.

Dr Andreas Turberg, Bayer HealthCare AG, Division Animal Health, Monheim, Germany.

Prof Hilary Ranson (Professor in Medical Entomology) Liverpool School of Tropical Medicine.

+44 (0) 1582 763 133 ext: +44 1582 938759
Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ

Press releases

What makes the varroa parasite of honey bees resistant to chemical treatment?

GM moths 'can curb pest invasion'

Genetically modified diamondback moth offers pest control hope

A new tool for the management of Varroa mites in bee hives

La resistencia de Varroa a los piretroides

 Peer-reviewed research papers-

Field, L.M., Davies, T.G.E., O’Reilly, A.O., Williamson, M.S., Wallace, B.A. (2017) Voltage-gated sodium channels as targets for pyrethroid insecticides. European Biophysics Journal. DOI:10.1007/s00249-016-1195-1.

Garrood, W.T., Zimmer,  C.T., Gutbrod, O., Lüke, B., Williamson, M.S., Bass, C., Nauen, R., Davies T.G.E. (2017) Influence of the RDL A301S mutation in the brown planthopper Nilaparvata lugens on the activity of phenylpyrazole insecticides. Pesticide Biochemistry & Physiology. DOI:10.1016/j.pestbp.2017.01.007.

ffrench-Constant, R., Williamson, M.S., Davies T.G.E., Bass C (2016) Ion channels as insecticide targets. Journal of Neurogenetics, DOI:10.1080/01677063.2016.1229781. 

Troczka, B.J., Williamson, M.S., Field, L.M., Davies, T.G.E. (2016) Rapid selection for resistance to diamide insecticides in Plutella xylostella via specific amino acid polymorphisms in the ryanodine receptor. NeuroToxicology DOI: 10.1016/j.neuro.2016.05.012.

González-Cabrera, J., Rodriguez-Vargas, S., Davies,T.G.E.,  Field, L.M., Schmehl, D., Ellis, J.D. Krieger, K., Williamson, M.S. (2016) Novel Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Varroa destructor Populations from the Southeastern USA. PLoS ONE 11(5) DOI: 10.1371/journal.pone.0155332.

Zimmer, C.T., Garrood, W.T., Puinean, A.M., Eckel-Zimmer, M., Williamson, M.S., Davies, T.G.E., Bass, C. (2016) A CRISPR/Cas9 mediated point mutation in the alpha 6 subunit of the nicotinic acetylcholine receptor confers resistance to spinosad in Drosophila melanogaster. IBMB 73: 62-69.

Troczka, B.J. Williams, A.J., Williamson, M.S., Field, L.M., Lüemmen. P, Davies, T.G.E. (2015) Stable expression and functional characterisation of the diamondback moth ryanodine receptor G4946E variant conferring resistance to diamide insecticides. Scientific Reports 5: 14680 DOI: 0.1038/srep14680.

Harvey-Samuel, T., Morrison, N.I. Walker, A.S., Marubbi, T., Yao, J., Collins, H.L.,Gorman, K., Davies, T.G.E., Alphey, N., Warner, S., Shelton, A.M., Alphey, L. (2015) Pest control and resistance management through release of insects carrying a male-selecting transgene. BMC Biology 13:49  DOI:10.1186/s12915-015-0161-1.

Garrood, W.T., Zimmer, C.T., Gorman, K.J., Nauen, R., Bass, C & Davies, T.G.E. (2015) Field-evolved resistance to imidacloprid and ethiprole in populations of brown planthopper Nilaparvata lugens collected from across South and East Asia. Pest Management Science - DOI: 10.1002/ps.3980.

Amey, J.S, O’Reilly, A.O., Burton, M.J., Puinean, A.M, Mellor, I.R., Duce, I.R., Field, L.M., Wallace, B.A., Williamson, M.S., Davies, T.G.E. (2015) An evolutionarily-unique heterodimeric voltage-gated cation channel found in aphids. Febs Lett  589: 598-607. DOI:10.1016/j.febslet.2015.01.020.

Troczka, B.J., Williams, A.J., Bass, C., Williamson, M.S., Field, L.M., Davies, T.G.E. (2015) Molecular cloning, characterisation and mRNA expression of the ryanodine receptor from the peach-potato aphid, Myzus persicae. GENE  556: 106-112. DOI: 10.1016/j.gene.2014.11.035.

O'Reilly, A.O., Williamson, M.S., González-Cabrera,J., Turberg, A., Field, L.M., Wallace, B.A., Davies, T.G.E. (2014) Predictive 3D modelling of the interactions of pyrethroids with the voltage-gated sodium channels of ticks and mites. Pest Management Science 70: 369-377.

González-Cabrera,J., Davies, T.G.E., Field, L.M., Kennedy, P.J., Williamson, M.S. (2013) An amino acid substitution (L925V) associated with resistance to pyrethroids in Varroa destructor. PLOS ONE DOI: 10.1371/journal.pone.0082941. 

Troczka, B., Zimmer, C.T., Elias, J., Schorn, C., Bass, C., Davies, T.G.E., Field, L.M., Williamson, M.S., Slater, R., Nauen, R (2012) Resistance to diamide insecticides in diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) is associated with a mutation in the membrane-spanning domain of the ryanodine receptor. Insect Biochemistry and Molecular Biology 42: 873-880.

Davies, T.G.E., Field, L.M. & Williamson, M.S. (2012) The re-emergence of the bed bug as a nuisance pest: implications of resistance to pyrethroid insecticides. Medical and Veterinary Entomology 26: 241-254.

Burton, M.J., Mellor, I.M., Duce, I.R., Davies, T.G.E., Field, L.M. & Williamson, M.S. (2011) Differential resistance of insect sodium channels with kdr mutations to deltamethrin, permethrin and DDT. Insect Biochemistry Molecular Biology 41: 723-732.

The International Aphid Genomics Consortium [...Davies, T.G.E, Williamson, M.S. & Field, L.M.] (2010) Genome Sequence of the Pea Aphid Acyrthosiphon pisum. PLoS Biology 8(2): e1000313. doi:10.1371.

Dale, R.P., Jones, A.K., Tamborindeguy, C., Davies, T.G.E., Amey, J.S., Williamson, S., Wolstenholme,A., Field, L.M., Williamson, M.S., Walsh, T.& Sattelle, D.B. (2010) Identification of ion channel genes in the Acyrthosiphon pisum genome. Insect Molecular Biology 19 (Suppl. 2): 141–153.

Davies, T.G.E & Williamson, M.S. (2009) Interactions of pyrethroids with the voltage-gated sodium channel. Bayer CropScience Journal 62: 159-178

Peng, F., Mellor, I.R., Williamson, M.S., Davies, T.G.E., Field, L.M. & Usherwood, P.N.R. (2009) Single channel study of deltamethrin interactions with wild-type and mutated rat NaV1.2 sodium channels expressed in Xenopus oocytes NeuroToxicology 30: 358–367.

Davies, T.G.E, O’Reilly A.O., Field, L.M., Wallace, B.A. & Williamson, M.S. (2008). Knockdown resistance to DDT and pyrethroids: from target-site mutations to molecular modelling. Pest Management Science 64: 1126-1130.

Usherwood, P.N.R., Davies, T.G.E., Mellor, I.R., O’Reilly, A.O., Peng, F., Vais, H., Khambay, B.P.S., Field, L.M. & Williamson, M.S. (2007). Mutations in DIIS5 and the DIIS4-S5 linker of the Drosophila para sodium channel define binding domains for pyrethroids and DDT. Febs Letters 581: 5485-5492.

Davies, T.G.E., Field, L.M., Usherwood P.N.R & Williamson M.S. (2007). DDT, pyrethrins, pyrethroids and insect sodium channels. IUBMB-Life 59: 151-162.

Davies, T.G.E., Field, L.M., Usherwood P.N.R & Williamson M.S. (2007). A comparative study of voltage-gated sodium channels in the Insecta: implications for pyrethroid resistance in Anopheline and other Neopteran species. Insect Molecular Biology 16: 361-375.

O'Reilly, A.O., Khambay, B.P.S., Williamson, M.S., Field, L.M., Wallace, B.A. & Davies, T.G.E. (2006). Modelling insecticide binding sites in the voltage-gated sodium channel. Biochemical Journal. 396: 255-263.

Usherwood, P.N.R., Vais, H., Khambay B., Davies, T.G.E. & Williamson, M.S. (2005). Sensitivity of the Drosophila para sodium channel to DDT is not lowered by a super-kdr mutation on the IIS4-S5 linker that profoundly reduces sensitivity to permethrin and deltamethrin. Febs Letters. 579: 6317–6325.

 Davies, T.G.E., Ying, J., Xu, Q., Li, Z-S., Li, J. & Gordon-Weeks, R. (2002). Expression analysis of putative high-affinity phosphate transporters in Chinese winter wheats. Plant Cell & Environment 25: 1325-1339.

Gordon-Weeks, R., Tong, Y., Davies, T.G.E. & Leggewie, G. (2003). Restricted spatial expression of a high-affinity phosphate transporter in potato roots. Journal of Cell Science 116: 3135-3144.

Chandran, H., Davies, T.G.E.*, Sanchez-Fernandez, R.*, Coleman, J.O.D. & Rea, P.A. (2001). ABC proteins in Arabidopsis. Genome Biology. 01/2001; 276(10). DOI:10.1186/gb-2001-2-10-reports0037

Davies, T.G.E.*, Sanchez-Fernandez, R.*, Coleman, J.O.D. & Rea, P.A. (2001). The Arabidopsis thaliana ABC protein superfamily: a complete inventory. Journal of Biological Chemistry 276: 30231-30244.

Sanchez-Fernandez, R., Davies, T.G.E., Coleman, J.O.D. & Rea, P.A. (2001). Do plants have more genes than humans? Yes when it comes to ABC transporters. Trends in Plant Science 6: 347-348.

Davies, T.G.E. & Coleman, J.O.D. (2000). The Arabidopsis thaliana ATP-binding cassette proteins: an emerging superfamily. Plant, Cell and Environment 23: 431-443.

Coleman, J., Kalff, M. & Davies, T.G.E. (1997). Detoxification of xenobiotics by plants: chemical modification and vacuolar compartmentation. Trends in Plant Science 2: 144-151.

Davies, T.G.E., Theodolou, F.L., Hallahan, D.L. & Forde, B.G. (1997). Cloning and characterisation of a novel P-glycoprotein homologue from barley. Gene. 199: 195-202.

Gordon-Weeks, R, Parmar, S.J., Davies, T.G.E. & Leigh, R.A. (1999). Structural aspects of the effectiveness of bisphosphonates as competitive inhibitors of the plant vacuolar proton-pumping pyrophosphatase. Biochemical Journal 337: 373-377.

Davies, T.G.E, Steele, S.H., Walker, D.J. & Leigh, R.A. (1996). An analysis of vacuole development in oat aleurone protoplasts. Planta. 198: 356-364.

Wright, K.M., Davies, T.G.E., Steele, S.H., Leigh, R.A. & Oparka, K.J. (1992). Development of a probenecid-sensitive Lucifer Yellow transport system in vacuolating oat aleurone protoplasts. Journal of Cell Science. 102: 133-139.

Thomas, H., Ougham, H.J. & Davies, T.G.E. (1992). Leaf senescence in a non-yellowing mutant of Festuca pratensis. Transcripts and translation products. Journal of Plant Physiology 139: 403-412.

Davies, T.G.E., Thomas, H. & Rogers, L.J. (1990). Immunochemical quantification of cytochrome f in leaves of a non-yellowing senescence mutant of Festuca pratensis. Photosynthesis Research 24: 99-108.

Ougham, H.J. & Davies, T.G.E. (1990). Leaf development in Lolium temulentum: gradients of RNA complement and transcripts of plastid and non-plastid genes. Physiologia Plantarum 79: 331-338.

Davies, T.G.E., Thomas, H., Thomas, B.J. & Rogers, L.J. (1990). Leaf senescence in a non-yellowing mutant of Festuca pratensis: metabolism of cytochrome f. Plant Physiology 93: 588-595.

Davies, T.G.E., Thomas, B.J., Thomas, H. & Rogers L.J. (1990). Leaf development in Lolium temulentum: formation of the photosynthetic apparatus in the presence of the porphyrin synthesis inhibitor gabaculine. Journal of Experimental Botany 41: 905-917.

Bennett, A.P., Davies, T.G.E., Thomas, H., & Rogers, L.J. (1989). Co-ordination of chromophore-apoprotein synthesis in the developing leaf of Avena sativa L. Biochemical Society Transactions 18, 499-500.

Davies, T.G.E., Ougham, H.J., Thomas, H. & Rogers L.J. (1989). Leaf development in Lolium temulentum: plastid membrane polypeptides in relation to assembly of the photosynthetic apparatus and leaf growth. Physiologia Plantarum 75: 47-54.

Davies, T.G.E., Rogers, L.J. & Thomas, H. (1989). Purification and antigenicity of cytochrome f from meadow fescue, Festuca pratensis. Huds and cross reactivity of the antibodies with the protein from other plant species. Plant Physiology & Biochemistry 27: 889-898.

Davies, T.G.E., Thomas, H. & Rogers, L.J. (1988). Catabolism of cytochrome f in a senescence mutant of Festuca pratensis. Biochemical Society Transactions 16, 1054.




PhD in Molecular Biology (University of Wales/IGER)


BSc in Plant Biochemistry (University of Wales, Swansea)

Measures of esteem


  • The biological and molecular factors influencing the control of two whitefly species (Bemisia tabaci and Trialeurodes vaporium) on different host plants: BBSRC/Syngenta University of Exeter


  • Editorial Board Member: International Journal of Molecular Sciences
  • Editorial Board Member: Nature Scientific Reports


  • New opportunities to investigate insecticide and acaricide ion channel targets through their differential interactions with novel chemical agonists: Nottingham DTP / Bayer Animal Health
  • Innovating insect production to counter malnutrition and support aquaculture in Africa: Nottingham DTP
  • Investigation and characterisation of diamide insecticide resistance conferred by target-site mutations in the ryanodine receptor of lepidopteran pests with special reference to diamondback moth, Plutella xylostella: Bayer CropScience


  • The biological and molecular factors influencing the control of two whitefly species (Bemisia tabaci and Trialeurodes vaporium) on different host plants: BBSRC / Syngenta
  • Investigating the molecular and biochemical basis of insecticide selectivity against the solitary bee Osmia bicornis: Bayer Crop Science funded studentship


  • Editorial Board Member: Advances in Zoology and Botany
  • Investigating the breakdown of chemical control in brown planthoppers from Asia: Bayer CropScience funded studentship
  • Characterizing the aphid voltage-gated sodium channel as an insecticide target: Nottingham


  • Ryanodine Receptors: novel insecticide targets: BBSRC-Quota - External supervisor - Alan Williams, BHF Sir Thomas Lewis Professor of Cardiovascular Science, WHRI, Cardiff University


  • Fellow of Royal Entomological Society
  • Fellow of the Royal Entomological Society (FRES)
  • Molecular Basis of Pyrethroid Resistance: Lawes Trust Studentship (University of Nottingham)


  • Ticks, Tickicides, and Tick Neuronal target profiling: BBSRC Industrial Studentship