|HUBHACHEN, ZHAORIGETU - Kansas State University
|JIANG, HONGBO - Southwest University
|SCHLIPALIUS, DAVID - Agri-Sciences Queensland
|PARK, YOONSEONG - Kansas State University
|GUEDES, RAUL N. - Universidade Federal De Vicosa
|OPIT, GEORGE - Oklahoma State University
|PHILLIPS, THOMAS - Kansas State University
Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2019
Publication Date: 6/19/2019
Citation: Hubhachen, Z., Jiang, H., Schlipalius, D., Park, Y., Guedes, R.C., Oppert, B.S., Opit, G., Phillips, T.W. 2019. A CAPS marker for determination of strong phosphine resistance in Tribolium castaneum from Brazil. Journal of Pest Science. https://doi.org/10.1007/s10340-019-01134-4.
Interpretive Summary: Populations of the red flour beetle have been described with strong resistance to phosphine, the primary fumigant used to control the insect. Mutations in one gene, called DLD, have been demonstrated to be responsible for this resistance. DLD was sequenced in a phosphine resistant strain of the flour beetle from Brazil and the mutations were characterized. These data were used to evaluate the genotypes found in individual insects from this population. Information from this study can be used to develop genetic markers to identify phosphine resistant insects in the field.
Technical Abstract: Strong phosphine resistance in Tribolium castaneum is due to one or more point mutations that code for amino acid changes of P45S or/and G131S in the enzyme dihydrolipoamide dehydrogenase (DLD). One allele coding for P45S is the most common in all USA populations and in one strain from Brazil, whereas another allele, for G131S, occurs only in Australia. Dose mortality studies found the Brazilian strain of T. castaneum (TCBR) is more resistant to phosphine than US populations. To investigate strong resistance mutations in TCBR, we sequenced its cDNA for DLD and compared results with US populations from Kansas and Alabama. The common P45S mutation was detected in all three populations, but two additional mutations G131D and V167A were identified only from TCBR. We used a CAPS marker (Cleaved Amplified Polymorphic Sequence) for P45S, herein designated M1, to survey this resistance allele in TCBR. We also developed a marker for the G131D mutation, designated M2. Only two genotypes, R1R1S2S2 (homozygous for resistance at M1, but homozygous susceptible at the M2 site) and R1S1R2S2 (heterozygous for resistance at M1 and M2) existed in TCBR. Strengths of phosphine resistance were similar between individuals with the two genotypes. Beetles with strong resistance in TCBR may be homozygous for either the presence of the common P45S allele, or heterozygous for two resistance alleles at a second locus, G131D. The strong-resistance phenotype in TCBR may be expressed differently based on previously unknown mutations at the DLD locus, but this will require further research to resolve.