Publications by authors named "Nigel Beebe"

Article Synopsis
  • The study investigates the genetic diversity of the mosquito species Culex annulirostris, a significant arbovirus vector in Australasia, confirming it comprises at least two distinct species based on mitochondrial and nuclear DNA analyses.
  • Researchers developed 12 microsatellite markers and studied over 500 individuals to assess population genetics across Australia, Papua New Guinea, and the Solomon Archipelago.
  • Findings reveal two main genetically distinct populations of Cx. annulirostris in mainland Australia, with potential admixture in certain regions, highlighting the species' complex population structure and geographical distribution.
View Article and Find Full Text PDF

Indoor insecticide applications are the primary tool for reducing malaria transmission in the Solomon Archipelago, a region where Anopheles farauti is the only common malaria vector. Due to the evolution of behavioural resistance in some An. farauti populations, these applications have become less effective.

View Article and Find Full Text PDF

Background: Although whole-genome sequencing (WGS) is the preferred genotyping method for most genomic analyses, limitations are often experienced when studying genomes characterized by a high percentage of repetitive elements, high linkage, and recombination deserts. The Asian tiger mosquito (Aedes albopictus), for example, has a genome comprising up to 72% repetitive elements, and therefore we set out to develop a single-nucleotide polymorphism (SNP) chip to be more cost-effective. Aedes albopictus is an invasive species originating from Southeast Asia that has recently spread around the world and is a vector for many human diseases.

View Article and Find Full Text PDF

During preliminary mosquito surveys at Cowley Beach Training Area in north Queensland, Australia, it was found that the utility of the standard encephalitis virus surveillance (EVS) trap for collecting the malaria vector Anopheles farauti (Laveran) adults was compromised by the harsh tropical conditions. With the aim of increasing the survival rate of mosquitoes, we designed a downdraft fan box trap (FBT) that incorporated a screened fan at the bottom of the trap, so mosquitoes did not have to pass through a fan. The FBT was tested against the EVS and Centers for Disease Control (CDC) light traps, where mosquitoes do pass through a fan, and a nonpowered passive box trap (PBT).

View Article and Find Full Text PDF
Article Synopsis
  • The dengue mosquito is a key vector for several dangerous viruses, and its spread globally has been influenced by globalization from the 15th to the 20th century.
  • A lack of historical invasion records and understanding of the mosquito's population genetics in Southeast Asia and the Indo-Pacific has been noted, despite the region being significantly affected by diseases it transmits.
  • The study uses microsatellites and mitochondrial sequences to analyze population structure across the Indo-Pacific, revealing previously unrecognized genetic differentiation and population breaks that can inform control strategies and predict future invasions.
View Article and Find Full Text PDF

Background: Incompatible insect technique (IIT) is a population suppression approach based on the release of males with manipulated Wolbachia infection inducing egg inviability in wild females. We here present results of multiple field releases of incompatible ARwP males carried out in 2019 in a 2.7-ha green area within urban Rome (Italy) to assess the effect on Aedes albopictus egg viability.

View Article and Find Full Text PDF
Article Synopsis
  • Dengue control in Bangladesh relies heavily on targeting the Aedes aegypti mosquito with insecticides, but increasing insecticide resistance is making these efforts less effective, worsened by a significant outbreak in 2019.
  • High levels of resistance to commonly used insecticides like pyrethroids have been observed in Dhaka, with studies showing minimal mortality rates in tested mosquito populations, indicating metabolic resistance mechanisms at play.
  • The findings suggest a need to explore alternative insecticides and develop more sustainable approaches to effectively manage and control dengue vectors moving forward.
View Article and Find Full Text PDF

Background: Anopheles farauti is one of the major vectors of malaria in the Southwest Pacific region and is responsible for past outbreaks in Australia. With an adaptable biting profile conducive to behavioural resistance to indoor residual spraying (IRS) and insecticide-treated nets (ITNs), its all-night biting behaviour can switch to biting mostly in the early evening. With limited insight into the biting profile of An.

View Article and Find Full Text PDF
Article Synopsis
  • Biological control using Wolbachia bacteria shows promise in managing mosquito-borne diseases, as demonstrated with the wAlbB2-F4 strain of Aedes aegypti.
  • Field trials revealed that male wAlbB2-F4 mosquitoes significantly reduced wild mosquito populations through cytoplasmic incompatibility and exhibited resistance to dengue and Zika viruses.
  • Genetic analyses confirmed over 98% Australian ancestry in wAlbB2-F4 mosquitoes, allowing them to maintain local traits while being effective for both population suppression and replacement strategies against viral infections.
View Article and Find Full Text PDF

We investigate the genetic basis of anthropophily (human host use) in a non-model mosquito species group, the complex from the southwest Pacific. This complex has experienced multiple transitions from anthropophily to zoophily, contrasting with well-studied systems (the global species and the African complex) that have evolved to be specialist anthropophiles. By performing tests of selection and assessing evolutionary patterns for >200 olfactory genes from nine genomes, we identify several candidate genes associated with differences in anthropophily in this complex.

View Article and Find Full Text PDF

Releasing sterile or incompatible male insects is a proven method of population management in agricultural systems with the potential to revolutionize mosquito control. Through a collaborative venture with the "Debug" Verily Life Sciences team, we assessed the incompatible insect technique (IIT) with the mosquito vector in northern Australia in a replicated treatment control field trial. Backcrossing a US strain of carrying AlbB from with a local strain, we generated a AlbB2-F4 strain incompatible with both the wild-type (no ) and Mel- now extant in North Queensland.

View Article and Find Full Text PDF

is a mosquito species with variable host preference. Throughout New Guinea and northern Australia, .  feeds on humans (it is opportunistically anthropophagic) while in the south-west Pacific's Solomon Archipelago, the species is abundant but has rarely been found biting humans (it is exclusively zoophagic in most populations).

View Article and Find Full Text PDF

Rapid advances in biological and digital support systems are revolutionizing the population control of invasive disease vectors such as Aedes aegypti. Methods such as the sterile and incompatible insect techniques (SIT/IIT) rely on modified males to seek out and successfully mate with females, and in doing so outcompete the wild male population for mates. Currently, these interventions most frequently infer mating success through area-wide population surveillance and estimates of mating competitiveness are rare.

View Article and Find Full Text PDF
Article Synopsis
  • In urban areas, pyrethroid insecticides are commonly used to control Aedes aegypti mosquitoes, but their effectiveness is decreasing due to resistance and other factors.
  • Sublethal exposure to the insecticide permethrin negatively affected susceptible mosquitoes but had mixed effects on insecticide-resistant ones, including decreased lifespan and increased mating success.
  • This resistance may be reinforced over time, as the persistent sublethal exposure could enhance the competitiveness and fecundity of resistant mosquito populations.
View Article and Find Full Text PDF

Background: The development of insecticide resistance in mosquitoes can have pleiotropic effects on key behaviours such as mating competition and host-location. Documenting these effects is crucial for understanding the dynamics and costs of insecticide resistance and may give researchers an evidence base for promoting vector control programs that aim to restore or conserve insecticide susceptibility.

Methods And Findings: We evaluated changes in behaviour in a backcrossed strain of Aedes aegypti, homozygous for two knockdown resistance (kdr) mutations (V1016G and S989P) isolated in an otherwise fully susceptible genetic background.

View Article and Find Full Text PDF

Background: Effective vector control measures are essential in a world where many mosquito-borne diseases have no vaccines or drug therapies available. Insecticidal tools remain the mainstay of most vector-borne disease management programmes, although their use for both agricultural and public health purposes has resulted in selection for resistance. Despite this, little is known about the fitness costs associated with specific insecticide-resistant genotypes and their implications for the management of resistance.

View Article and Find Full Text PDF

New Guinea is a topographically and biogeographically complex region that supports unique endemic fauna. Studies describing the population connectivity of species through this region are scarce. We present a population and landscape genetic study on the endemic malaria-transmitting mosquito, (Owen).

View Article and Find Full Text PDF

Background: In the Solomon Island, the dominant malaria vector, Anopheles farauti, is highly anthropophagic and increasingly exophilic and early biting. While long-lasting insecticide-treated nets remain effective against An. farauti, supplemental vector control strategies will be needed to achieve malaria elimination.

View Article and Find Full Text PDF

Background: Sterile male rear-and-release programmes are of growing interest for controlling Aedes aegypti, including use an "incompatible insect technique" (IIT) to suppress transmission of dengue, Zika, and other viruses. Under IIT, males infected with Wolbachia are released into the suppression area to induce cytoplasmic incompatibility in uninfected populations. These and similar mosquito-release programmes require cost-effective field surveys of both sexes to optimize the locations, timing, and quantity of releases.

View Article and Find Full Text PDF

Background: Malaria transmission varies in intensity amongst Solomon Island villages where Anopheles farauti is the only vector. This variation in transmission intensity might be explained by density-dependent processes during An. farauti larval development, as density dependence can impact adult size with associated fitness costs and daily survivorship.

View Article and Find Full Text PDF

As the incidence of arboviral diseases such as dengue, Zika, chikungunya, and yellow fever increases globally, controlling their primary vector, Aedes aegypti (L.) (Diptera: Culicidae), is of greater importance than ever before. Mosquito control programs rely heavily on effective adult surveillance to ensure methodological efficacy.

View Article and Find Full Text PDF

Background: Species in the Anopheles farauti complex are major malaria vectors in the Asia Pacific region. Anopheline mosquitoes exhibit circadian and diel rhythms in sugar- and blood-feeding (biting), flight activity, oviposition, and in some species, a short-lived dusk/early night associated swarming behaviour during which mating occurs. A behavioural study of wild-caught mosquitoes from Queensland, Australia was conducted to investigate the differences in diel rhythmic flight activity between two cryptic species in several reproductive states.

View Article and Find Full Text PDF

Background: Decisions on when vector control can be withdrawn after malaria is eliminated depend on the receptivity or potential of an area to support vector populations. To guide malaria control and elimination programmes, the potential of biting rates, sporozoite rates, entomological inoculation rates and parity rates to estimate malaria receptivity and transmission were compared within and among geographically localised villages of active transmission in the Western Province of the Solomon Islands.

Results: Malaria transmission and transmission potential was heterogeneous in both time and space both among and within villages as defined by anopheline species composition and biting densities.

View Article and Find Full Text PDF

Mosquitoes' importance as vectors of pathogens that drive disease underscores the importance of precise and comparable methods of taxa identification among their species. While several molecular targets have been used to study mosquitoes since the initiation of PCR in the 1980s, its application to mosquito identification took off in the early 1990s. This review follows the research's recent journey into the use of mitochondrial DNA (mtDNA) cytochrome oxidase 1 (COI or COX1) as a DNA barcode target for mosquito species identification - a target whose utility for discriminating mosquitoes is now escalating.

View Article and Find Full Text PDF