Displaying all 7 publications

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  1. Razali M, Palmer RM, Coward P, Wilson RF
    Br Dent J, 2005 Apr 23;198(8):495-8; discussion 485.
    PMID: 15849588
    Smoking has been associated with increased risk of periodontitis. The aim of the present study was to compare the periodontal disease severity of adult heavy smokers and never-smokers referred for assessment and treatment of chronic periodontitis.
  2. Chou LY, Dykes GA, Wilson RF, Clarke CM
    Environ Entomol, 2016 Feb;45(1):201-6.
    PMID: 26518035 DOI: 10.1093/ee/nvv164
    Nepenthes pitcher plants are colonized by a variety of specialized arthropods. As Aedes mosquitoes are container breeders, Nepenthes pitchers are a potential candidate oviposition site for vector species, such as Aedes aegypti (L.) and Aedes albopictus (Skuse). However, Aedes spp. are not commonly encountered in Nepenthes pitchers, and the environment inside the pitchers of some species is lethal to them. One exception is Nepenthes ampullaria Jack, whose pitchers are known to be colonized by Ae. albopictus on very rare occasions. Given that Ae. albopictus larvae can survive in N. ampullaria pitcher fluids, we sought to determine why pitcher colonization is rare, testing the hypothesis that gravid Aedes mosquitoes are deterred from ovipositing into container habitats that have similar characteristics to N. ampullaria pitchers. Using plastic ovitraps of different sizes, colors, and with different types of fluids (based on the characteristics of N. ampullaria pitchers), we compared oviposition rates by Aedes mosquitoes in urban and rural areas within the geographical range of N. ampullaria near Kuala Lumpur, Malaysia. Ovitraps that were black and large (>250-ml capacity) accumulated significantly more eggs than ovitraps that were smaller, or green in color. In terms of size and color, small, green ovitraps are analogous to N. ampullaria pitchers, indicating that these pitchers are not particularly attractive to gravid Ae. albopictus. Although Aedes spp. are capable of colonizing N. ampullaria pitchers, the pitchers are relatively unattractive to gravid females and do not represent a significant habitat for larvae of dengue vectors at present.
  3. Ahmad M, Pitt Ford TR, Crum LA, Wilson RF
    Oral Surg. Oral Med. Oral Pathol., 1990 Sep;70(3):328-32.
    PMID: 2216361
    The physical mechanisms of ultrasound, namely cavitation and acoustic streaming, generated by the Enac-Osada ultrasonic unit were investigated for effectiveness in disrupting Streptococcus mitis. In addition, the bactericidal effect of ultrasound in the presence of 2.5% sodium hypochlorite was examined. Bacterial suspensions were irradiated directly with ultrasound in simulated root canals, and the viability of bacteria was examined after growth on a blood agar medium under anaerobic conditions at 37 degrees C for 5 days. The results indicated that ultrasound per se failed to disrupt bacteria but resulted in increases in the viable counts; the former was considered to be because of the lack of cavitation and the latter because of the dispersal effects of acoustic streaming. The 2.5% sodium hypochlorite solution demonstrated powerful bactericidal activity.
  4. Lee JM, Yek SH, Wilson RF, Rahman S
    Acta Trop, 2020 Dec;212:105683.
    PMID: 32888935 DOI: 10.1016/j.actatropica.2020.105683
    Understanding the diversity and dynamics of the microbiota within the mosquito holobiome is of great importance to apprehend how the microbiota modulates various complex processes and interactions. This study examined the bacterial composition of Aedes albopictus across land use type and mosquito sex in the state of Selangor, Malaysia using 16S rRNA sequencing. The bacterial community structure in mosquitoes was found to be influenced by land use type and mosquito sex, with the environment and mosquito diet respectively identified to be the most likely sources of microbes. We found that approximately 70% of the microbiota samples were dominated by Wolbachia and removing Wolbachia from analyses revealed the relatively even composition of the remaining bacterial microbiota. Furthermore, microbial interaction network analysis highlighted the prevalence of co-exclusionary patterns in all networks regardless of land use and mosquito sex, with Wolbachia exhibiting co-exclusionary interactions with other residential bacteria such as Xanthomonas, Xenophilus and Zymobacter.
  5. Lee JM, Wasserman RJ, Gan JY, Wilson RF, Rahman S, Yek SH
    Ecohealth, 2020 03;17(1):52-63.
    PMID: 31786667 DOI: 10.1007/s10393-019-01457-9
    Knowledge of the interrelationship of mosquito communities and land use changes is of paramount importance to understand the potential risk of mosquito disease transmission. This study examined the effects of land use types in urban, peri-urban and natural landscapes on mosquito community structure to test whether the urban landscape is implicated in increased prevalence of potentially harmful mosquitoes. Three land use types (park, farm, and forest nested in urban, peri-urban and natural landscapes, respectively) in Klang Valley, Malaysia, were surveyed for mosquito larval habitat, mosquito abundance and diversity. We found that the nature of human activities in land use types can increase artificial larval habitats, supporting container-breeding vector specialists such as Aedes albopictus, a dengue vector. In addition, we observed a pattern of lower mosquito richness but higher mosquito abundance, characterised by the high prevalence of Ae. albopictus in the urban landscape. This was also reflected in the mosquito community structure whereby urban and peri-urban landscapes were composed of mainly vector species compared to a more diverse mosquito composition in natural landscape. This study suggested that good environmental management practices in the tropical urban landscape are of key importance for effective mosquito-borne disease management.
  6. Sukiato F, Wasserman RJ, Foo SC, Wilson RF, Cuthbert RN
    J Vector Ecol, 2019 12;44(2):264-270.
    PMID: 31729799 DOI: 10.1111/jvec.12358
    Urbanization has caused an increase in favorable habitats for Aedes aegypti (Diptera: Culicidae), given their ability to reproduce in small and often non-degradable artificial water-containers. While much work has been done on Ae. aegypti biology and ecology in urban landscapes, the role of shading on immature stages as an independent factor from temperature, and any possible interactions between these factors, remains unexamined. We assessed how temperature and shading affected egg hatch-rate, larval/pupal mortality, and larval development to adult stage under different factorial temperature (28; 31; 34; 37; 40° C) and shade (0%, 3,100 lux; 40%, 1,860 lux; 75%, 775 lux; 100%, 0 lux) regimes. Hatch-rate was significantly lower at 37° C (57 %), and no eggs hatched at 40° C. There was no significant effect caused by shading on hatchability. Larval and pupal mortality at 37° C was significantly higher (35%) compared to lower temperature groups, while the effects of shading were emergent at low temperatures. Developmental times from hatching to adult emergence were significantly reduced with increasing temperatures and with greater light exposures. The eco-physiological response of Ae. aegypti larvae to temperature and light regimes suggest a photosensitivity previously unstudied in this species.
  7. Lee JM, Wasserman RJ, Wilson RF, Cuthbert RN, Rahman S, Yek SH
    Ecohealth, 2023 Mar;20(1):65-73.
    PMID: 37129695 DOI: 10.1007/s10393-023-01629-8
    Fogging with insecticides is one of the main control measures for adult mosquito populations employed in countries that are affected by dengue. In many such countries, urban communities are increasingly characterised by high-density residence in high-rise condominia. Although fogging is typically applied at the ground level, its efficacy in three-dimensional urban environments is poorly understood. Here, we investigated the effect of fogging on vector mosquito distribution and abundance in high-rise condominia by conducting a before-after fogging survey. We showed that although mosquitoes were significantly concentrated at the lower levels in high-rise condominia, they were found throughout the three-dimensional environments. Fogging did not significantly alter this distribution or abundance pattern across any floor level. Thus, any fogging effect was short-lived as mosquito populations recovered within a few days before the subsequent scheduled treatment. In addition, increasing fogging frequency within practicable limits did not prolong the intended control effect. As urban mosquitoes are increasingly insusceptible to fogging due to insecticide resistance and vertical avoidance, this study demonstrates the need to implement other mosquito control strategies for high-rise condominia to manage mosquito populations.
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