title: Phosphine resistance in India is characterised by a dihydrolipoamide dehydrogenase variant that is otherwise unobserved in eukaryotes.
abstract: Phosphine (PH3) fumigation is the primary method worldwide for controlling insect pests of stored commodities. Over-reliance on phosphine, however, has led to the emergence of strong resistance. Detailed genetic studies previously identified two loci, rph1 and rph2, that interact synergistically to create a strong resistance phenotype. We compared the genetics of phosphine resistance in strains of Rhyzopertha dominica and Tribolium castaneum from India and Australia, countries having similar pest species but widely differing in pest management practices. Sequencing analysis of the rph2 locus, dihydrolipoamide dehydrogenase (dld), identified two structurally equivalent variants, Proline49>Serine (P49S) in one R. dominica strain and P45S in three strains of T. castaneum from India. These variants of the DLD protein likely affect FAD cofactor interaction with the enzyme. A survey of insects from storage facilities across southern India revealed that the P45/49S variant is distributed throughout the region at very high frequencies, in up to 94% of R. dominica and 97% of T. castaneum in the state of Tamil Nadu. The abundance of the P45/49S variant in insect populations contrasted sharply with the evolutionary record in which the variant was absent from eukaryotic DLD sequences. This suggests that the variant is unlikely to provide a strong selective advantage in the absence of phosphine fumigation.
authors: 1] School of Biological Sciences, University of Queensland, St Lucia, Queensland, Australia [2] Agri-Science Queensland, Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia [3] Plant Biosecurity Cooperative Research Centre (PBCRC), Bruce, Australian Capital Territory, Australia.
authors: R
authors: R
authors: Kaur
authors: Department of Plant Biotechnology, Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore, India.
authors: M
authors: M
authors: Subbarayalu
authors: 1] School of Biological Sciences, University of Queensland, St Lucia, Queensland, Australia [2] Agri-Science Queensland, Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia.
authors: R
authors: R
authors: Jagadeesan
authors: 1] Agri-Science Queensland, Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia [2] Plant Biosecurity Cooperative Research Centre (PBCRC), Bruce, Australian Capital Territory, Australia.
authors: G J
authors: GJ
authors: Daglish
authors: 1] Agri-Science Queensland, Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia [2] Plant Biosecurity Cooperative Research Centre (PBCRC), Bruce, Australian Capital Territory, Australia.
authors: M K
authors: MK
authors: Nayak
authors: Department of Agricultural Entomology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore, India.
authors: H R
authors: HR
authors: Naik
authors: Department of Plant Biotechnology, Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore, India.
authors: S
authors: S
authors: Ramasamy
authors: Department of Agricultural Entomology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore, India.
authors: C
authors: C
authors: Subramanian
authors: School of Biological Sciences, University of Queensland, St Lucia, Queensland, Australia.
authors: P R
authors: PR
authors: Ebert
authors: 1] Agri-Science Queensland, Department of Agriculture, Fisheries and Forestry, Ecosciences Precinct, Brisbane, Queensland, Australia [2] Plant Biosecurity Cooperative Research Centre (PBCRC), Bruce, Australian Capital Territory, Australia.
authors: D I
authors: DI
authors: Schlipalius
mesh_terms: D000818:Animals; D001315:Australia; D001517:Coleoptera / Q000201:enzymology / Q000235:genetics*; D008058:Dihydrolipoamide Dehydrogenase / Q000235:genetics*; D019143:Evolution, Molecular; D061353:Food Storage; D005651:Fumigation; D005787:Gene Frequency; D007194:India; D019476:Insect Proteins / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides; D010720:Phosphines; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D014231:Tribolium / Q000201:enzymology / Q000235:genetics
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D010720:Phosphines; D008058:Dihydrolipoamide Dehydrogenase; C044646:phosphine