Oviposition of Aedes aegypti and Aedes albopictus on Ovitraps in Dry and Rainy Seasons in Southern Vietnam.

Ovitraps were set inside and outside of 15 households in December 2012 (dry season) and August 2013 (rainy season) in 2 communes (An Thanh and Phu Hoa) of Binh Duong Province in southern Vietnam. Eggs laid in the ovitraps were collected after 4 days, dried, and soaked in water. Hatched larvae were transferred to cups and reared to adulthood to identify the species. The rate of positive ovitraps did not differ between December and August for Aedes aegypti, but it was lower in December for Ae. albopictus. The number of eggs laid per ovitrap by Ae. aegypti did not differ between December and August, while that for Ae. albopictus decreased significantly in December in both communes. Moreover, Ae. albopictus laid eggs in ovitraps placed outside the households. Therefore, it is necessary for future studies to investigate whether the major source containers for oviposition had dried in the dry season or Ae. albopictus entered diapause, leading to these observations.

French invasive Asian tiger mosquito populations harbor reduced bacterial microbiota and genetic diversity compared to Vietnamese autochthonous relatives.

The Asian tiger mosquito Aedes albopictus is one of the most significant pathogen vectors of the twenty-first century. Originating from Asia, it has invaded a wide range of eco-climatic regions worldwide. The insect-associated microbiota is now recognized to play a significant role in host biology. While genetic diversity bottlenecks are known to result from biological invasions, the resulting shifts in host-associated microbiota diversity has not been thoroughly investigated. To address this subject, we compared four autochthonous Ae. albopictus populations in Vietnam, the native area of Ae. albopictus, and three populations recently introduced to Metropolitan France, with the aim of documenting whether these populations display differences in host genotype and bacterial microbiota. Population-level genetic diversity (microsatellite markers and COI haplotype) and bacterial diversity (16S rDNA metabarcoding) were compared between field-caught mosquitoes. Bacterial microbiota from the whole insect bodies were largely dominated by Wolbachia pipientis. Targeted analysis of the gut microbiota revealed a greater bacterial diversity in which a fraction was common between French and Vietnamese populations. The genus Dysgonomonas was the most prevalent and abundant across all studied populations. Overall genetic diversities of both hosts and bacterial microbiota were significantly reduced in recently established populations of France compared to the autochthonous populations of Vietnam. These results open up many important avenues of investigation in order to link the process of geographical invasion to shifts in commensal and symbiotic microbiome communities, as such shifts may have dramatic impacts on the biology and/or vector competence of invading hematophagous insects.