Biology subjects

Paris, V.

Publications and source records attributed to Paris, V..

8 recordsLinked to original sources

bioRxiv2026

Efficacy of 60 personal mosquito repellents and perfumes against Aedes aegypti mosquitoes

Personal insect repellents can offer an effective means of preventing mosquito bites. Despite a wide variety of products that claim to repel mosquitoes, relatively few studies have systematically compared their performance through standardized tests. In Australia, chemical-based repellents must be registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA); however, many unregistered products with unverified effectiveness remain commercially available. Here, we tested 55 insect repellents and 5 non-repellent perfumes and deodorants sold in Australia for their protection against Aedes aegypti mosquito landings (as a proxy for bites) using arm-in-cage assays across eight human subjects. We tested 43 topical repellents (containing 18 different primary active ingredients), four wristbands, three clothing stickers, three ultrasonic devices, one garment, one repellent applied to fabric, two perfumes, two deodorants and one antiperspirant. Thirteen repellents, including all wristbands, stickers and ultrasonic devices did not provide complete protection against mosquito landings for any human subject, while a further sixteen provided complete protection for 1 hr or less on average. Repellents containing DEET, oil of lemon eucalyptus, picaridin and IR3535 as the primary active ingredient were the only products that provided more than 2 hours of complete protection, but with significant variation among products with the same active ingredient. Only 7/30 essential oil-based topical repellents and perfumes provided complete protection for greater than 1 hr. Nearly half (25/52) of the repellents subject to registration with the APVMA were unregistered despite being advertised or labelled as mosquito repellents, and these tended to be less effective than registered products. Only 5/28 repellents met or exceeded their claimed protection time. This study highlights the prevalence of unregistered and ineffective mosquito repellents on the Australian market while providing evidence for products and active ingredients that do protect against mosquito bites under laboratory conditions.

zoology↗

bioRxiv2026

Strong reproductive isolation among sympatric lineages of an international mosquito pest

Background: Reproductive isolation describes the degree to which genetic differences among populations reduce the level of neutral gene flow between them. Genomic approaches are currently showing great utility for identifying reproductive isolation between sympatric, morphologically indistinct populations, where hybridisation and introgression may yet be common. Here we use population genomic approaches and a chromosome-level reference assembly to uncover three highly differentiated, cryptic lineages of Aedes notoscriptus, an Australian mosquito disease vector that has invaded New Zealand (c. 1920) and California (c. 2014). Results: We identified a single lineage (Noto1) that was the source of the New Zealand and Californian invasions, and this lineage was also distributed across much of Australia including the Greater Melbourne region where it was sympatric with a second lineage (Noto2). Although Victorian Noto1 and Noto2 were frequently sampled co-locally, hybrids were observed less frequently than expected under random mating, and admixture levels were low, suggestive of selection against hybrids. A bottleneck observed in Victorian Noto1 suggests that Noto1 may have recently expanded its range into the Greater Melbourne region. We also identified a massive structural variant (~25 Mbp; ~10% of chromosome size) in Noto2 that was segregating at intermediate frequencies across the Greater Melbourne region but was fixed in Noto1. Conclusion: Together, these results identify key genetic differences between cryptic lineages of this international disease vector that warrant further investigation given potential differences in vector competence.

evolutionary biology↗

bioRxiv2026

Interactions between inbreeding, fitness and the bacterial microbiome in Aedes aegypti mosquitoes

Laboratory and field populations of insects can experience a decline in fitness and loss of genetic diversity due to inbreeding depression and genetic drift, respectively. Matings among related individuals and small population size may also influence insect host microbiomes with consequences for fitness. In the dengue vector mosquito, Aedes aegypti, the bacterial microbiome is largely environmentally determined but recent studies have also revealed host genetic components. We generated a panel of 55 inbred lines from either of two founding outbred populations of Ae. aegypti to test for associations between life history traits, inbreeding, allelic diversity and microbiome composition using ddRADseq and bacterial 16S rRNA gene sequencing on pools of mosquitoes. Effects of inbreeding were diverse with severe composite fitness costs in many lines but minimal costs in others despite similar low levels of genetic diversity. We found no strong relationship between major life history traits across inbred lines, suggesting that any costs due to inbreeding were trait specific. Bacterial microbiome analysis of pooled samples from a subset of populations revealed common microbes across populations, with Elizabethkingia, Aeromonas and Ralstonia being the most abundant. Despite bacterial composition varying widely, there was no clear relationship between microbiome composition and fitness or population origin. However, there were several significant positive correlations between the relative abundance of different microbial taxa across lines. Our results demonstrate diverse impacts of inbreeding on fitness of mosquito populations but with limited impacts on the microbiome.

microbiology↗

bioRxiv2023

Evaluation of In2Care mosquito stations for suppression of the Australian backyard mosquito, Aedes notoscriptus

Aedes notoscriptus (Skuse) is a container-inhabiting mosquito endemic to Australia that vectors arboviruses and is suspected to transmit Mycobacterium ulcerans, the cause of Buruli ulcer. We evaluated the effectiveness of the In2Care(R) station, which suppresses mosquito populations via the entomopathogenic fungus, Beauveria bassiana, and the insect growth regulator pyriproxyfen, the latter of which is autodisseminated among larval habitats by contaminated mosquitoes. A field trial was conducted using 110 In2Care(R) stations in a 50,000 m2 area and results were compared to four control areas that did not receive the treatment. Efficacy was evaluated by comparing egg counts and measuring larvicidal impact in surrounding breeding sites. Laboratory experiments validated the effect of B. bassiana on adult survival. Results of this field trial indicate that, six weeks after the In2Care(R) stations were deployed, treatment site ovitraps contained 43% fewer eggs than control site ovitraps, and 33% fewer eggs after ten weeks, suggesting that the In2Care(R) station was able to reduce the egg density of Ae. notoscriptus. Population reduction remained evident for up to three weeks after In2Care(R) stations were removed. Treatment site ovitraps had significantly fewer Ae. notoscriptus eclosing than control site ovitraps, confirming the pyriproxyfen autodissemination feature of the stations. An average reduction of 50% in adult eclosion was achieved. Exposure to B. bassiana resulted in four-times higher mortality among adult mosquitoes. Additionally, using fresh In2Care(R) nettings led to an 88% decrease in average survival compared to four-week-old nettings. The use of In2Care(R) stations has potential for suppressing Ae. notoscriptus egg density.

ecology↗

bioRxiv2023

How often are male mosquitoes attracted to humans?

Many mosquito species live close to humans where females feed on human blood. While male mosquitoes do not feed on blood, it has long been recognized that males of some species can be attracted to human hosts. To investigate the frequency of male mosquito attraction to humans, we conducted a literature review and human-baited field trials, as well as laboratory experiments involving males and females of three common Aedes species. Our literature review indicated that male attraction to humans is limited to a small number of species, including Ae. aegypti and Ae. albopictus. In our human-baited field collections, only 4 out of 13 species captured included males. In laboratory experiments, we found that male Ae. notoscriptus and Ae. vigilax showed no attraction to humans, while male Ae. aegypti exhibited persistent attraction for up to 30 minutes. Both male and female Ae. aegypti displayed similar preferences for different human subjects, suggesting that male Ae. aegypti respond to similar cues as females. Additionally, we found that mosquito repellents applied to human skin effectively repelled male mosquitoes. These findings shed light on mosquito behaviour and have implications for mosquito control programs, particularly those involving the release or monitoring of the male mosquito population.

animal behavior and cognition↗

bioRxiv2022

Urban population structure and local movement ecology of a native Australian mosquito involved in disease transmission

Dispersal is a critical factor in designing successful pest control measures as it determines the rate of movement across target control areas and influences the risk of human exposure to the species and its pathogens. Here we used a fine scale spatial population genomic approach to investigate the dispersal ecology and population structure of Aedes notoscriptus, an important disease transmitting mosquito, on the Mornington Peninsula near Melbourne, Australia. The species is suspected to be involved in the transmission of Mycobacterium ulcerans, the bacterium that causes Buruli ulcer, in this area. We sampled and reared Ae. notoscriptus eggs at two time points from 170 traps up to 5 km apart and generated genomic data from 240 individuals. We also produced a draft genome assembly from a laboratory colony established from mosquitoes sampled near the study area. We found low genetic structure (Fst) and high coancestry throughout the study region. Using genetic data to identify close kin dyads, we found that mosquitoes had moved distances of >1km within a generation, which is further than previously described for this species. A spatial autocorrelation analysis of genetic distances indicated genetic dissimilarity at >4 km separation, a fourfold higher distance than for a comparable population of the dengue mosquito, Ae. aegypti, from Cairns, Australia. These findings point to high mobility of Ae. notoscriptus, highlighting the challenges of localized intervention strategies targeting this species. Further sampling within the same area at two time points 6 and 12 months after initial sampling showed that egg counts were relatively consistent across time, and that spatial variation in egg counts covaried with spatial variation in Wrights neighbourhood size (NS). As NS increases linearly with population density, egg counts may be useful for estimating relative density in Ae. notoscriptus. The results highlight the importance of acquiring species-specific data when planning control measures.

ecology↗

bioRxiv2018

Effects of alternative blood sources on Wolbachia infected Aedes aegypti females within and across generations

Wolbachia bacteria have been identified as a tool for reducing the transmission of arboviruses transmitted by Aedes aegypti. Research groups around the world are now mass rearing Wolbachia infected Ae. aegypti for deliberate release. We investigated the fitness impact of a crucial element of mass rearing: the blood meal required by female Ae. aegypti to lay eggs. Although Ae. aegypti almost exclusively feed on human blood, it is often difficult to use human blood in disease-endemic settings. When females were fed on sheep or pig blood rather than human blood, egg hatch rates decreased in all three lines tested (uninfected, or infected by wMel, or wAlbB Wolbachia). This finding was particularly pronounced when fed on sheep blood, although fecundity was not affected. Some of these effects persisted after an additional generation on human blood. Attempts to keep populations on sheep and pig blood sources only partly succeeded, suggesting that strong adaptation is required to develop a stably infected line on an alternative blood source. There was a decrease in Wolbachia density when Wolbachia Ae. aegypti were fed on non-human blood sources, although density was higher again in lines kept for multiple generations on the alternate sources. These findings suggest that sheep and pig blood will entail a cost when used as alternative blood sources which needs to be taken into account when considering mass release.

evolutionary biology↗

bioRxiv2018

A constitutively expressed antifungal peptide protects Tenebrio molitor during a natural infection by the entomopathogenic fungus Beauveria bassiana.

Antimicrobial peptides have been well studied in the context of bacterial infections. Antifungal peptides have received comparatively less attention. Fungal pathogens of insects and their hosts represent a unique opportunity to study host-pathogen interactions due to the million of years of co-evolution they share. In this study, we investigated role of a constitutively expressed thaumatin-like peptide with antifungal activity expressed by the mealworm beetle Tenebrio molitor, named Tenecin 3, during a natural infection with the entomopathogenic fungus Beauveria bassiana. We monitored the effect of the expression of Tenecin 3 on the survival of infected hosts as well as on the progression of the fungal infection inside the host. Finally, we tested the activity of Tenecin 3 against B. bassiana. These findings could help improving biocontrol strategies and help understanding the evolution of antifungal peptides as a defense mechanism.

immunology↗