The hemipteran whitefly Bemisia tabaci (Gennadius) is one of the most destructive pests damaging more than 600 agricultural crop species worldwide. The B and Q biotypes are most widely spread in Korea but they are not distinguishable based on morphological characters. Carboxylesterase 2 (Coe2) was determined to be 5.9 times more expressed in B biotype compared to Q biotype. Comparison of deduced amino acid sequences of Coe2 (595 a.a.) showed a total of 3.85% polymorphisms between B and Q types but no differences in major active sites. Quantitative real-time PCR revealed that both B and Q biotypes possess a single copy of coe2, suggesting that the overexpression of Coe2 in B biotype is likely due to overtranscription. To determine the putative role of Coe2 in insecticide tolerance, esterases were separated by native isoelectric focusing (IEF) and inhibited by various insecticides. The putative Coe2 band was apparently inhibited by pyrethroid and organophosphate insecticides, but not by imidacloprid. These findings suggest that overexpression of Coe2 confers chemical defense against pyrethroid and organophosphate insecticides, perhaps by sequestration.

To search for hyper-variable genetic markers that can distinguish regional populations of head lice, we screened the inter simple sequence repeats (ISSR) based on the genome database of body louse, which is closely related conspecific species. An ISSR mining software, SciRoKo 3.4, was employed to excavate ISSR markers from the genome database under the MISA mode (≥ 60 bp repeats). Entire body louse genome (ca.100 Mb) was loaded to SciRoKo for ISSRs mining. A total of 5,336 ISSRs were obtained, and primers specific to individual ISSRs were designed by the Primer 3 and DesignPrimer 1.0 softwares. In order to prove the compatibility of body louse ISSRs to head lice, 31 PCR primers were randomly chosen out of a total of 613 pairs, and their appropriateness was tested by comparing the amplified PCR band patterns between body and head lice. Eleven primer pairs that resulted in poor or little amplification were excluded, and 20 primer pairs were further tested for three head louse populations (California, Panama and Chung-ju, Korea). Finally, nine primer pairs ensuring robust amplification of highly variable band patterns were selected to use for population genetic study of head lice.