Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2009305 | Pesticide Biochemistry and Physiology | 2013 | 11 Pages |
•The DDT-resistant 91-R is highly resistant to DDT.•Resistance is polyfactorial.•Cuticular penetration of DDT is significantly reduced in the 91-R strain.•Excretion of unaltered DDT is significantly increased in the 91-R strain.•Oxidative, reductive and conjugative xenobiotic metabolisms are increased in the 91-R strain.
Resistance to 4,4′-dichlorodiphenyltrichloroethane (DDT) in the 91-R strain of Drosophila melanogaster is extremely high compared to the susceptible Canton-S strain (>1500 times). In addition to enhanced oxidative detoxification, the 91-R strain also has a reduced rate of DDT penetration, increased levels of reductive and conjugative metabolism, and substantially more excretion than the Canton-S strain. Contact penetration of DDT was ∼30% less with 91-R flies, which also had significantly more cuticular hydrocarbons and a thicker, more laminated cuticle compared to Canton-S flies, possibly resulting in penetration differences. DDT was metabolized ∼1.6-fold more extensively by 91-R than Canton-S flies, resulting in dichlorodiphenyldichloroethane (DDD), two unidentified metabolites and polar conjugates being formed in significantly greater amounts. 91-R flies also excreted ∼4-fold more DDT and metabolites than Canton-S flies. Verapamil pretreatment reduced the LD50 value for 91-R flies topically dosed with DDT by a factor of 10-fold, indicating that the increased excretion may involve, in part, ATP-binding cassette (ABC) transporters. In summary, DDT resistance in 91-R is polyfactorial and includes reduced penetration, increased detoxification and direct excretion.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide