scholarly journals Sex-specific distribution and classification of Wolbachia infections and mitochondrial DNA haplogroups in Aedes albopictus from the Indo-Pacific

2022 ◽  
Author(s):  
Qiong Yang ◽  
Jessica Chung ◽  
Katie Robinson ◽  
Thomas L Schmidt ◽  
Perran Ross ◽  
...  

The arbovirus vector Aedes albopictus (Asian tiger mosquito) is common throughout the Indo-Pacific region, where most global dengue transmission occurs. We analysed population genomic data and tested for cryptic species in 160 Ae. albopictus sampled from 16 locations across this region. We found no evidence of cryptic Ae. albopictus but found multiple intraspecific COI haplotypes partitioned into groups representing three Asian lineages: East Asia, Southeast Asia and Indonesia. Papua New Guinea (PNG), Vanuatu and Christmas Island shared recent coancestry, and Indonesia and Timor-Leste were likely invaded from East Asia. We used a machine learning trained on morphologically sexed samples to classify sexes using multiple genetic features and then characterized the w AlbA and w AlbB Wolbachia infections in 664 other samples. The w AlbA and w AlbB infections as detected by qPCR showed markedly different patterns in the sexes. For females, most populations had a very high double infection incidence, with 67% being the lowest value (from Timor-Leste). For males, the incidence of double infections ranged from 100% (PNG) to 0% (Vanuatu). Only 6 females were infected solely by the w AlbA infection, while rare uninfected mosquitoes were found in both sexes. The w AlbA and w AlbB densities varied significantly among populations. For mosquitoes from Torres Strait and Vietnam, the w AlbB density was similar in single-infected and superinfected ( w AlbA and w AlbB) mosquitoes. There was a positive association between w AlbA and w AlbB infection densities in superinfected Ae. albopictus . Our findings provide no evidence of cryptic species of Ae. albopictus in the region and suggest site-specific factors influencing the incidence of Wolbachia infections and their densities. We also demonstrate the usefulness of SNPs as sex-specific mosquito markers. The results provide baseline data for the exploitation of Wolbachia -induced cytoplasmic incompatibility (CI) in dengue control.

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 167
Author(s):  
John H. Boyle ◽  
Pasi M. A. Rastas ◽  
Xin Huang ◽  
Austin G. Garner ◽  
Indra Vythilingam ◽  
...  

The Asian tiger mosquito, Aedes albopictus, is an invasive vector mosquito of substantial public health concern. The large genome size (~1.19–1.28 Gb by cytofluorometric estimates), comprised of ~68% repetitive DNA sequences, has made it difficult to produce a high-quality genome assembly for this species. We constructed a high-density linkage map for Ae. albopictus based on 111,328 informative SNPs obtained by RNAseq. We then performed a linkage-map anchored reassembly of AalbF2, the genome assembly produced by Palatini et al. (2020). Our reassembled genome sequence, AalbF3, represents several improvements relative to AalbF2. First, the size of the AalbF3 assembly is 1.45 Gb, almost half the size of AalbF2. Furthermore, relative to AalbF2, AalbF3 contains a higher proportion of complete and single-copy BUSCO genes (84.3%) and a higher proportion of aligned RNAseq reads that map concordantly to a single location of the genome (46%). We demonstrate the utility of AalbF3 by using it as a reference for a bulk-segregant-based comparative genomics analysis that identifies chromosomal regions with clusters of candidate SNPs putatively associated with photoperiodic diapause, a crucial ecological adaptation underpinning the rapid range expansion and climatic adaptation of A. albopictus.


2019 ◽  
Author(s):  
Maria Vittoria Mancini ◽  
Christie S. Herd ◽  
Thomas H. Ant ◽  
Shivan M. Murdochy ◽  
Steven P. Sinkins

AbstractThe global incidence of arboviral diseases transmitted by Aedes mosquitoes, including dengue, chikungunya, yellow fever, and Zika, has increased dramatically in recent decades. The release of Aedes aegypti carrying the maternally inherited symbiont Wolbachia as an intervention to control arboviruses is being trialled in several countries. However, these efforts are compromised in many endemic regions due to the co-localization of the secondary vector Aedes albopictus, the Asian tiger mosquito. Ae. albopictus has an expanding global distribution following incursions into a number of new territories. To date, only the wMel and wPip strains of Wolbachia have been reported to be transferred into and characterized in this vector. A Wolbachia strain naturally infecting Drosophila simulans, wAu, was selected for transfer into a Malaysian Ae. albopictus line to create a novel triple-strain infection. The newly generated line showed self-compatibility, moderate fitness cost and complete resistance to Zika and dengue infections.Author summaryAedes albopictus, the invasive Asian tiger mosquito, is responsible for numerous outbreaks of important viruses such as dengue and Zika in various regions of the world. The need for alterative control interventions propelled the development of a novel approach that exploits a natural insect symbiont, Wolbachia; when transferred into non-native hosts, these maternally-inherited bacteria are able to interfere with the transmission of mosquito-borne viruses, and also provide reproductive advantages to the host, offering a promising tool for self-sustaining field applications. Currently, several field trials are ongoing for the primary vector of dengue and several other arboviruses, Aedes aegypti, providing encouraging results. In this study, Ae. albopictus has been targeted for a similar approach: this mosquito species naturally carries two strains of Wolbachia. The artificial introduction of a third, non-native strain made this line less able to transmit dengue and Zika viruses and had an impact on its fitness.


Author(s):  
Thomas L Schmidt ◽  
Jessica Chung ◽  
Anthony R. van Rooyen ◽  
Angus Sly ◽  
Andrew R Weeks ◽  
...  

AbstractBACKGROUNDUnderstanding pest incursion pathways is critical for preventing new invasions and for stopping the transfer of alleles that reduce the efficacy of local control methods. The mosquitoes Aedes albopictus (Skuse) and Ae. aegypti (Linnaeus) are both highly invasive disease vectors, and through a series of ongoing international incursions are continuing to colonise new regions and spread insecticide resistance alleles among established populations. This study uses high-resolution molecular markers and a set of 241 reference genotypes to trace incursion pathways of Ae. albopictus into mainland Australia, where no successful invasions have yet been observed. We contrast these results with incursion pathways of Ae. aegypti, investigated previously.RESULTSAssignments successful identified China, Japan, Singapore and Taiwan as source locations. Incursion pathways of Ae. albopictus were entirely different to those of Ae. aegypti, despite broad sympatry of these species throughout the Indo-Pacific region. Incursions of Ae. albopictus appeared to have come predominantly along marine routes from key trading locations, while Ae. aegypti was mostly linked to aerial routes from tourism hotspots.CONCLUSIONThese results demonstrate how genomics can help decipher otherwise cryptic incursion pathways. The inclusion of reference genotypes from the Americas may help resolve some unsuccessful assignments. While many congeneric taxa will share common incursion pathways, this study highlights that this is not always the case, and incursion pathways of important taxa should be specifically investigated. Species differences in aerial and marine incursion rates may reflect the efficacy of ongoing control programs such as aircraft disinsection.


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