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The cotton aphid, Aphis gossypii Glover, is one of the most important agricultural insect pests. Pyrethroid and neonicotinoid insecticides have generally shown excellent control of A. gossypii, but many populations of this pest have developed resistance against these classes of insecticides. The success of insecticide resistance management strategies requires detailed knowledge of both phenotype and genotype of the target insect pest. In this study, we attempted to understand the molecular status of insecticide resistance in cotton aphid populations in Xinjiang Uygur Autonomous Region of China, the major cotton planting region of China. In addition to the previously reported M918L mutation, we discovered another substitution (M918V) in the voltage‐gated sodium channel (VGSC). Moreover, we developed a molecular assay that could be used to detect precisely the R81T mutation in the nicotinic acetylcholine receptor (nAChR). This survey revealed that 918L was the predominant VGSC allele with a frequency ranging from 50.0% to 56.7%. Notably, appreciable frequencies (between 10% and 40%) of the resistance 81T allele of the nAChR gene were detected in three investigated populations. The prevalent co‐occurrence of both VGSC 918L/V and nAchR 81T indicates a worrisome situation of multiple resistance to both pyrethroids and neonicotinoids. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: The house fly Musca domestica is an important disease vector. Point mutation‐mediated target‐site insensitivity of the voltage sensitive sodium channel (VSSC) and increased detoxification mediated by cytochrome P450 (CYP6D1) overexpression have been characterized as two major mechanisms of pyrethroid resistance. In this study, genetic mutations in the Vssc and CYP6D1 genes and their contribution to pyrethroid resistance were investigated. RESULTS: Twelve lines of house flies homozygous for four genotypes were established. House flies carrying the VSSC 1014F mutation and overexpressing CYP6D1 had higher resistance to pyrethroids than those carrying 1014F alone. The presence of the 15‐bp insert in the promoter region of the CYP6D1 gene did not necessarily result in a significant increase in CYP6D1 mRNA and pyrethroid resistance levels. A novel Vssc allele carrying two mutations (G1924D and G2004S) in combination with the classic 1014F and a novel CYP6D1 allele that is very similar to CYP6D1v1 were identified in Chinese house flies. CONCLUSION: This work demonstrates the effect of genetic mutations in CYP6D1 and Vssc on the susceptibility of house flies to pyrethroids, and verifies that 15‐bp insert‐containing CYP6D1 alleles have a single origin. These findings offer insights into the evolution of insecticide resistance and have implications for house fly control. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Increased insecticide detoxification mediated by cytochrome P450s is a common mechanism of insecticide resistance. Although Cyp6a2 has been observed to be overexpressed in many 4,4′-dichlorodiphenyltrichloroethane ( DDT)-resistant strains of Drosophila melanogaster, how Cyp6a2 is regulated and whether its overproduction confers DDT resistance remain elusive. RESULTS Molecular analysis identified five Cyp6a2 alleles ( Cyp6a2Canton−S-1, Cyp6a2Canton−S-2, Cyp6a291-C, Cyp6a291-R and Cyp6a2Wisconsin− WD) from four D. melanogaster strains, notably differing in the presence or absence of an intact Nrf2/Maf (a transcription factor) binding site in the 5′-promoter core region, a ' G1410' frameshift deletion mutation in the heme-binding region and a long terminal repeat ( LTR) of transposable element 17.6 in the 3′-untranslated region ( UTR). Linkage analysis confirmed that DDT resistance was genetically linked to a Nrf2/Maf-binding-site-containing, LTR-lacking functional allele of Cyp6a2 ( Cyp6a291-R). The qRT-PCR results showed that overexpression of functional Cyp6a2 was consistently associated with DDT resistance. Luciferase reporter gene assays revealed that an intact Nrf2/Maf binding site in the 5′-promoter core region enhanced the constitutive transcription of Cyp6a2. CONCLUSION The results suggest that the Nrf2/Maf binding-site-containing functional Cyp6a2 allele is associated with DDT resistance in the D. melanogaster strains under study. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background Moderate to high DDT resistance in generally associated with overexpression of multiple genes and therefore has been considered to be polygenic. However, very little information is available about the molecular mechanisms that insect populations employ when evolving increased levels of resistance. The presence of common regulatory motifs among resistance-associated genes may help to explain how and why certain suites of genes are preferentially represented in genomic-scale analyses. Results A set of commonly differentially expressed genes associated with DDT resistance in the fruit fly was identified on the basis of genome-wide microarray analysis followed by qRT-PCR verification. More genes were observed to be overtranscribed in the highly resistant strain ( 91-R) than in the moderately resistant strain ( Wisconsin) and susceptible strain ( Canton-S). Furthermore, possible transcription factor binding sites that occurred in coexpressed resistance-associated genes were discovered by computational motif discovery methods. Conclusion A glucocorticoid receptor ( GR)-like putative transcription factor binding motif ( TFBM) was observed to be associated with genes commonly differentially transcribed in both the 91-R and Wisconsin lines of DDT-resistant Drosophila. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The article presents a study on the identification of new cytochrome P450 genes and analysis of their expression profile and xenobiotic response to interpret the roles of cytochrome P450s in the Helicoverpa armigera. From H. armigera, a novel P450 cDNA, CYP9A17, was separated which showed the highest amino acid identity with CYP9A12. The results of the study indicate that after the gene duplication event, CYP9A12 and CYP9A17 genes in H. armigera might vary via subfunctionalisation.