Recent advances in the study of knockdown resistance mutations in Aedes mosquitoes with a focus on several remarkable mutations.

The Aedes mosquito, which transmits the dengue fever virus and other viruses, has acquired resistance to pyrethroid insecticides in a naturally selective manner. Massive use of insecticides has led to the worldwide expansion of resistant populations. The major factor in pyrethroid resistance is knockdown resistance (kdr) caused by amino acid mutation(s) in the voltage-gated sodium channel, which is the target site of this insecticide group.

Concomitant knockdown resistance allele, L982W + F1534C, in Aedes aegypti has the potential to impose fitness costs without selection pressure.

The Aedes aegypti mosquito, is an arbovirus vector that can spread dengue, chikungunya, Zika, and yellow fever. Pyrethroids are widely used to control mosquitoes. The voltage-gated sodium channel (Vgsc) is the target of pyrethroids, and amino acid substitutions in this channel attenuate the effects of pyrethroids.

Discovery of super-insecticide-resistant dengue mosquitoes in Asia: Threats of concomitant knockdown resistance mutations.

(Linnaeus, 1762) is the main mosquito vector for dengue and other arboviral infectious diseases. Control of this important vector highly relies on the use of insecticides, especially pyrethroids. The high frequency (>78%) of the L982W substitution was detected at the target site of the pyrethroid insecticide, the voltage-gated sodium channel (Vgsc) of collected from Vietnam and Cambodia.

Common substitution mutation F348Y of acetylcholinesterase gene contributes to organophosphate and carbamate resistance in Cimex lectularius and C. hemipterus.

Bed bug control highly depends on insecticides with a limited number of modes of action, especially since the global prevalence of pyrethroid resistance. De facto insecticide options against bed bugs in Japan are acetylcholinesterase inhibitors (AChEis) that consist of organophosphates and carbamates. However, the status of AChEi resistance and the mechanisms involved have not been ascertained.

A first, naturally occurring substitution at the second pyrethroid receptor of voltage-gated sodium channel of Aedes aegypti.

Background: Aedes aegypti is a remarkably effective mosquito vector of epidemiologically important arboviral diseases including dengue fever, yellow fever and Zika. The present spread of resistance against pyrethroids, the primary insecticides used for mosquito control, in global populations of this species is of great concern. The voltage-gated sodium channel (VGSC) in the nervous system is the known target site of pyrethroids in insects.

Genetic analysis of Aedes aegypti captured at two international airports serving to the Greater Tokyo Area during 2012-2015.

The introduction of exotic disease vectors into a new habitat can drastically change the local epidemiological situation. During 2012-2015, larvae and an adult of the yellow-fever mosquito, Aedes aegypti, were captured alive at two international airports serving the Greater Tokyo Area, Japan. Because this species does not naturally distribute in this country, those mosquitoes were considered to be introduced from overseas via air-transportation.

High-throughput genotyping of a full voltage-gated sodium channel gene via genomic DNA using target capture sequencing and analytical pipeline MoNaS to discover novel insecticide resistance mutations.

In insects, the voltage-gated sodium channel (VGSC) is the primary target site of pyrethroid insecticides. Various amino acid substitutions in the VGSC protein, which are selected under insecticide pressure, are known to confer insecticide resistance. In the genome, the VGSC gene consists of more than 30 exons sparsely distributed across a large genomic region, which often exceeds 100 kbp.

Predicting the Start of the Aedes albopictus (Diptera: Culicidae) Female Adult Biting Season Using the Spring Temperature in Japan.

Aedes albopictus (Skuse) (Diptera: Culicidae) is distributed widely and is common in much of Japan. In Japan, female adults begin to bite in between April and June, except in the southern subtropics where the mosquito has no dormant period. It is difficult to estimate the first Ae.

Testing the causality between CYP9M10 and pyrethroid resistance using the TALEN and CRISPR/Cas9 technologies.

Recently-emerging genome editing technologies have enabled targeted gene knockout experiments even in non-model insect species. For studies on insecticide resistance, genome editing technologies offer some advantages over the conventional reverse genetic technique, RNA interference, for testing causal relationships between genes of detoxifying enzymes and resistance phenotypes. There were relatively abundant evidences indicating that the overexpression of a cytochrome P450 gene CYP9M10 confers strong pyrethroid resistance in larvae of the southern house mosquito Culex quinquefasciatus.

A single nucleotide change in a core promoter is involved in the progressive overexpression of the duplicated CYP9M10 haplotype lineage in Culex quinquefasciatus.

Although the importance of cis-acting mutations on detoxification enzyme genes for insecticide resistance is widely accepted, only a few of them have been determined as concrete mutations present in genomic DNA till date. The overexpression of a cytochrome P450 gene, CYP9M10, is associated with pyrethroid resistance in the southern house mosquito Culex quinquefasciatus. The haplotypes of CYP9M10 exhibiting overexpression (resistant haplotypes) belong to one specific phylogenetic lineage that shares high nucleotide sequence homology and the same insertion of a transposable element.

Field and Laboratory Evaluations of the Efficacy of DEET Repellent against Ixodes Ticks.

The objective of this study was to clarify the efficacy of a currently available N,N-diethyl-m-toluamide (DEET) repellent against tick species in Japan. We performed 2 different field trials: "human trap," and "flag-dragging." In total, 482 ticks were collected from white flannel cloths in the field studies.

A single crossing-over event in voltage-sensitive Na+ channel genes may cause critical failure of dengue mosquito control by insecticides.

The voltage-sensitive sodium (Na+) channel (Vssc) is the target site of pyrethroid insecticides. Pest insects develop resistance to this class of insecticide by acquisition of one or multiple amino acid substitution(s) in this channel. In Southeast Asia, two major Vssc types confer pyrethroid resistance in the dengue mosquito vector Aedes aegypti, namely, S989P+V1016G and F1534C.

Mechanisms of pyrethroid resistance in the dengue mosquito vector, Aedes aegypti: target site insensitivity, penetration, and metabolism.

Aedes aegypti is the major vector of yellow and dengue fevers. After 10 generations of adult selection, an A. aegypti strain (SP) developed 1650-fold resistance to permethrin, which is one of the most widely used pyrethroid insecticides for mosquito control.

Geospatial analysis of invasion of the Asian tiger mosquito Aedes albopictus: competition with Aedes japonicus japonicus in its northern limit area in Japan.

The mosquito Aedes albopictus, indigenous to Southeast Asia and nearby islands, has spread almost worldwide during recent decades. We confirm the invasion of this mosquito, first reported in Yamagata city in northeast Honshu, Japan in 2000. Previously, only Ae.

Potential efficacy of olyset mosquito netting against Calliphora nigribarbis (Diptera: Calliphoridae) invasion into livestock barns.

Calliphora nigribarbis Vollenhoven is a possible mechanical transmitter of highly pathogenic avian influenza. Based on laboratory tests, we evaluated the efficacy of a long-lasting permethrin-treated mosquito netting, known as the Olyset net, for the prevention of this species entering livestock barns. Flies were trapped in Olyset net cages, and two statistics for knockdown and lethal efficacies were obtained.

Distribution of a knockdown resistance mutation (L1014S) in Anopheles gambiae s.s. and Anopheles arabiensis in western and southern Kenya.

In Kenya, insecticide-treated mosquito nets (ITNs) distributed to pregnant women and children under 5 years old through various programs have resulted in a significant reduction in malaria deaths. All of the World Health Organization-recommended insecticides for mosquito nets are pyrethroids, and vector mosquito resistance to these insecticides is one of the major obstacles to an effective malaria control program. Anopheles gambiae s.

Multimodal pyrethroid resistance in malaria vectors, Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus s.s. in western Kenya.

Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus s.

First detection of a putative knockdown resistance gene in major mosquito vector, Aedes albopictus.

The Asian tiger mosquito, Aedes albopictus (Skuse), is the major vector of Chikungunya fever and the secondary vector of dengue fever. We collected Ae. albopictus from Singapore and performed genotyping assay to detect mutations of the voltage-gated sodium channel, which is the target site of pyrethroid insecticides.

Cis-acting mutation and duplication: History of molecular evolution in a P450 haplotype responsible for insecticide resistance in Culex quinquefasciatus.

A cytochrome P450 gene, Cyp9m10, is more than 200-fold overexpressed in a pyrethroid resistant strain of Culex quinquefasciatus, JPal-per. The haplotype of this strain contains two copies of Cyp9m10 resulted from recent tandem duplication. In this study, we discovered and isolated a Cyp9m10 haplotype closely related to this duplicated Cyp9m10 haplotype from JHB, a strain used for the recent genome project for this mosquito species.

Genomic structures of Cyp9m10 in pyrethroid resistant and susceptible strains of Culex quinquefasciatus.

Development of insecticide resistance reduces the efficacy of controlling measures against the medical and agricultural insect pests. Cytochrome P450s are one of the major detoxification enzymes involved in insecticide metabolisms. Previously, we have reported that the P450 gene Cyp9m10 is about 260-fold overexpressed in a pyrethroid-resistant strain of Culex quinquefasciatus compared to a susceptible strain.

Overexpression of cytochrome P450 genes in pyrethroid-resistant Culex quinquefasciatus.

JPal-per strain of Culex quinquefasciatus exhibits extremely high resistance against pyrethroids in larvae, though the resistance is greatly lower in adults. Increased microsome monooxygenase metabolism is one of the major factors of the larval resistance in this strain. We cloned 46 novel cytochrome P450 cDNAs from JPal-per strain.