The dominant Anopheles vectors of human malaria in the Asia-Pacific region: occurrence data, distribution maps and bionomic précis

<p>Abstract</p> <p>Background</p> <p>The final article in a series of three publications examining the global distribution of 41 dominant vector species (DVS) of malaria is presented here. The first publication examined the DVS from the Americas, with the second covering those species present in Africa, Europe and the Middle East. Here we discuss the 19 DVS of the Asian-Pacific region. This region experiences a high diversity of vector species, many occurring sympatrically, which, combined with the occurrence of a high number of species complexes and suspected species complexes, and behavioural plasticity of many of these major vectors, adds a level of entomological complexity not comparable elsewhere globally. To try and untangle the intricacy of the vectors of this region and to increase the effectiveness of vector control interventions, an understanding of the contemporary distribution of each species, combined with a synthesis of the current knowledge of their behaviour and ecology is needed.</p> <p>Results</p> <p>Expert opinion (EO) range maps, created with the most up-to-date expert knowledge of each DVS distribution, were combined with a contemporary database of occurrence data and a suite of open access, environmental and climatic variables. Using the Boosted Regression Tree (BRT) modelling method, distribution maps of each DVS were produced. The occurrence data were abstracted from the formal, published literature, plus other relevant sources, resulting in the collation of DVS occurrence at 10116 locations across 31 countries, of which 8853 were successfully geo-referenced and 7430 were resolved to spatial areas that could be included in the BRT model. A detailed summary of the information on the bionomics of each species and species complex is also presented.</p> <p>Conclusions</p> <p>This article concludes a project aimed to establish the contemporary global distribution of the DVS of malaria. The three articles produced are intended as a detailed reference for scientists continuing research into the aspects of taxonomy, biology and ecology relevant to species-specific vector control. This research is particularly relevant to help unravel the complicated taxonomic status, ecology and epidemiology of the vectors of the Asia-Pacific region. All the occurrence data, predictive maps and EO-shape files generated during the production of these publications will be made available in the public domain. We hope that this will encourage data sharing to improve future iterations of the distribution maps.</p

Exploring the Acetone Evaporation and Airborne Neurotoxicity Bioassay Against Adult Mosquito in the Enclosed Environment of Peet Grady Chamber

Mosquito has comprehensive and sensitive olfactory neuro-sensory located at antenna utilized for detecting airborne organic compounds in search of blood host. Mosquito is also known to have similar neurotransmitters function with human at neural synapses e.g. acetylcholinesterase, esterases and oxidases enzymes. Thus, there is potential use mosquito in predicting neurotoxicity of exogenic volatile organic compounds (VOC) e.g. manufactured acetone. Hence, the study evaluates the suitability to conduct bioassay of VOC neurotoxicity against mosquito in Peet Grady chamber that is commonly used for insecticidal bioassay. Acetone as the representative of VOC is easily evaporized at laboratory temperature of 26 to 29 °C without heating. The acetone evaporation profile on liquid surface and porous solid surface under the Peet Grady chamber is studied to ascertain the consistency of vaporization rate with homogenized distribution. The study showed the acetone has shown consistent vaporization rate of 23 mg/min from liquid surface and 116.3 mg/min from porous surface (filter paper) without heating, in a linear regression of very high positive correlation (r = 1.000) between time and mass of acetone vaporized. However, the non-homogenized distribution of acetone vapours in the Peet Grady chamber directly affected the accuracy to elucidate the neurotoxicity bioassay against mosquito in term of mosquito knockdown. The study suggests the positioning of mosquitoes in the Peet Grady chamber should be lower than the point of acetone vaporization, whereby the mosquitoes are knockdown by acetone vapours within the 20th minute upon reaching concentration of 170.3 to 196.1 ppm

Unusual developing sites of dengue vectors and potential epidemiological implications

Objective: To identify the unusual breeding sites of two dengue vectors, i.e. Aedes albopictus (Ae. albopictus) and Aedes aegypti (Ae. aegypti). Methods: During the second half of 2010, we performed an occasional survey in rural (Teluk Tempoyak) and urban (Gelugor) areas ofPenang Island, Malaysia, to identify cryptic breeding sites. Results: In the rural area, we found heterogeneous immature stages of Ae. albopictus in the water bowl of an encaged bird. We also observed Ae. aegypti eggs deposited in the flush tank of a toilet in the urban area. Conclusions:It can be concluded that both breeding patterns can increase contact with hosts (humans and birds) and presumably population densities of Ae. albopictus and Ae. aegy

Discarded cigarette butts attract females and kill the progeny of aedes albopictus

Discarded cigarette butts (DCB) waste occurs worldwide, pollutes landscapes, is unsightly, and results in added debris removal costs. There is, therefore, a great deal of current interest in making use of DCBs in beneficial ways. Despite evidence that DCBs are harmful to water fleas (Daphnia magna), which breed in aquatic environments as do mosquito larvae, their impact on dengue vectors is unknown. We examined whether Aedes albopictus alters its ovipositional responses, larval eclosion, and development in response to presence of DCBs in its habitats. We found oviposition activity in DCB-treated water similar to that of control water and that ovipositional activity in DCB solutions steadily increased over time as those solutions aged to 10 days. Larval eclosion was initially suppressed on day 1 in DCB solution, but increased thereafter to levels similar to control larval eclosion rates. The DCB-water solutions produced significantly higher mortality in both 1st and 2nd instars over control larvae for several days after initial exposure. Mortality rates decreased sharply 3 to 5 days postexposure as DCBs continued to decompose. We found increased survival rates during late development, but daily input of fresh DCBs prevented most young larvae from completing development. Taken together, these observations suggest that decomposing did not deter gravid Ae. albopictus females from ovipositing in treated containers and that DCB solutions had larvicidal effects on early instars. Our results are discussed in the context of DCB use to control container-breeding Ae. albopictus, a competent dengue vector in Asia and other parts of the world