|Liu, Zhiqi - MICHIGAN STATE UNIVERSITY|
|Dong, Ke - MICHIGAN STATE UNIVERSITY|
Submitted to: Journal of Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 22, 2000
Publication Date: N/A
Interpretive Summary: Knockdown resistance, or kdr, is an insecticide resistance mechanism caused by mutations in nervous system proteins of some insects. This mechanism often completely eliminates the effectiveness of pyrethroid and related insecticides against many insect species. Although the kdr mechanism has been reported in several German cockroach strains, the single mutation in the para gene, which has been repeatedly reported in kdr resistant insects does not always correlate with the presence or magnitude of knockdown resistance. Scientists at Michigan State University and the USDA-ARS (Center for Medical, Agricultural and Veterinary Entomology) sequenced the para gene from recently collected field populations of German cockroach in an attempt to identify novel mutations that may be specifically responsible for knockdown resistance. Four new mutations were identified, two of which appear to be directly associated with knockdown resistance.
Technical Abstract: Knockdown resistance (kdr) to pyrethroid insecticides has been attributed to point mutations in the para sodium channel gene in more than a half dozen insect pest species. In this study, we identified two novel para mutations in five highly resistant kdr-type German cockroach strains. The two mutations, from glutamic acid (E434) to lysine (K434) and from cysteine e(C764) to arginine (R764), respectively, are located in the first intracellular linker connecting domains I and II. E434K is located near the beginning of the linker (closest to domain I), whereas C764R is found toward the end of the linker (closest to domain II). Two additional mutations from aspartic acid (D57) to glycine (G57), and from proline (P1888) to leucine (L1888), respectively, were found in one of the resistant strains. The four mutations co-exist with the previously identified L993F kdr mutation in IIS6 (Dong 1997) and are present only in the highly resistant individuals of a given strain. These findings sugges these mutations might be responsible for high levels of knockdown resistance toward pyrethroid insecticides in the German cockroach.