Insecticide resistance in a novel laboratory-produced greenbug (Homoptera: Aphididae) clone

To assess the potential development of new resistant greenbug genotypes, a greenbug clone with over-expressed esterase activity in 2 different esterases (identified by polyacrylamide gel electrophoresis) was created through laboratory breeding between pattern 1 (R1) and pattern 2 (R2) field-derived insecticide-resistant clones. This clone was tested for insecticide resistance to 2 insecticides. The laboratory created clone was designated pattern 3 (R3) and has not been discovered in the field. The R3 clone was compared with susceptible (S), R1, and R2 greenbug clones using an insecticide residue vial bioassay. The R1, R2, and R3 clones were significantly more resistant to parathion than the S clone. The LD50 values for the R1, R2, and R3 clones were 45.5-, 213.2-, and 134.0-fold (respectively) higher than the LD50 of the S clone. The R2 and R3 clones were found to be significantly more resistant to parathion than the R1 clone, but the differences between the R2 and R3 clones were not significant. The respective LD50 values for the R1, R2, and R3 clones were 1.64-, 1.73-, and 1.91-fold greater than the S clone when tested against carbofuran. However, these differences were not found to be significant, indicating little cross resistance to this carbamate insecticide. Control measures effective against R2 insects should be effective against R3 insects if they occur in the field.