Dataset Information

Diel flight activity of wild-caught Anopheles farauti (s.s.) and An. hinesorum malaria mosquitoes from northern Queensland, Australia.

ABSTRACT:

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.

Results

The 24-hour flight activity of individual adult female mosquitoes under light:dark cycle conditions were monitored with a minute-to-minute time resolution using an infrared beam break method. Mosquitoes were analyzed for reproductive state (insemination and parity) and identified to species [An. farauti (s.s.) Laveran and An. hinesorum Schmidt] by PCR analysis. We compared daily total flight activity, timing of activity onset, the peak in early nocturnal activity, and patterns of activity during the scotophase (night). Species-specific differences between An. farauti and An. hinesorum were observed. Compared to An. farauti, An. hinesorum had an earlier onset of dusk activity, an earlier peak in nocturnal activity, and a higher level of activity at the onset of darkness. Small differences between species were also observed in the pattern of the dusk/early-night bouts of activity. A second nocturnal peak in inseminated nulliparous An. hinesorum was also observed during the middle of the scotophase.

Conclusions

The behavioural differences between these two sympatric species of the An. farauti complex might contribute to subtle differences in habitat adaptation, the timing of host-seeking and/or sugar-feeding activity. This study provides baseline data for analysis of populations of mosquitoes from other geographical regions where these species are malaria vectors, such as in the Solomon Islands and Papua New Guinea. This is important as selective pressures due to long-term use of indoor residual spraying of insecticides and insecticide-treated bed nets are shifting the nocturnal profile of biting behaviour of these vectors to earlier in the night.

SUBMITTER: Duffield GE

PROVIDER: S-EPMC6341630 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Publications

Diel flight activity of wild-caught Anopheles farauti (s.s.) and An. hinesorum malaria mosquitoes from northern Queensland, Australia.

Duffield Giles E GE Acri Dominic J DJ George Gary F GF Sheppard Aaron D AD Beebe Nigel W NW Ritchie Scott A SA Burkot Thomas R TR

Parasites & vectors 20190122 1

<h4>Background</h4>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 ...[more]

PMID: 30670073

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Project description:BackgroundMonitoring of malaria vectors is important for designing and maintaining effective control interventions as changes in vector-feeding habits can threaten the efficacy of interventions. At present, human landing catches remain the most common method for monitoring malaria vectors of the Anopheles punctulatus complex, including the Anopheles farauti group. The aims of this study were to evaluate the efficacy of different lures and fan-powered traps, including an odour blend that has been demonstrated to be attractive to African anophelines, in Queensland, Australia.MethodsTo evaluate the performance of different lures in trapping An. farauti in the field, four Suna traps were baited with either: CO2-alone, a synthetic lure (MB5 or BG-Lure) plus CO2, or a human odour plus CO2 and set in the field in Cairns, eastern Australia. A second study evaluated the performance of four traps: a Passive Box trap, BG-Suna trap, BG-Sentinel 2 trap, and BG-Bowl trap, for their ability to trap An. farauti using the best lure from the first experiment. In both experiments, treatments were rotated according to a Latin square design over 16 nights. Trapped mosquitoes were identified on the basis of their morphological features.ResultsBG-Suna traps baited with CO2 alone, a BG-Lure plus CO2 or a natural human odour plus CO2 captured comparable numbers of An. farauti. However, the number of An. farauti sensu lato captured when the MB5 lure was used with CO2 was three times lower than when the other odour lures were used. The BG-Sentinel 2 trap, BG-Suna trap and BG-Bowl trap all captured high numbers of An. farauti, when baited with CO2 and a BG-Lure. The morphological condition of captured mosquitoes was affected by mechanical damage caused by all fan-powered traps but it was still possible to identify the specimens.ConclusionsThe BG-Sentinel 2 trap, BG-Suna trap and the BG-Bowl trap captured high numbers of An. farauti in the field, when equipped with CO2 and an odour lure (either the BG-Lure or a natural odour). The most important attractant was CO2. This study shows that fan-powered traps, baited with CO2 plus an appropriate odour lure, can be a promising addition to current vector monitoring methods in the Southwest Pacific.

Project description:Residual vector populations that do not come in contact with the most frequently utilized indoor-directed interventions present major challenges to global malaria eradication. Many of these residual populations are mosquito species about which little is known. As part of a study to assess the threat of outdoor exposure to malaria mosquitoes within the Southern and Central Africa International Centers of Excellence for Malaria Research, foraging female anophelines were collected outside households in Nchelenge District, northern Zambia. These anophelines proved to be more diverse than had previously been reported in the area. In order to further characterize the anopheline species, sequencing and phylogenetic approaches were utilized. Anopheline mosquitoes were collected from outdoor light traps, morphologically identified, and sent to Johns Hopkins Bloomberg School of Public Health for sequencing. Sanger sequencing from 115 field-derived samples yielded mitochondrial COI sequences, which were aligned with a homologous 488 bp gene segment from known anophelines (n = 140) retrieved from NCBI. Nuclear ITS2 sequences (n = 57) for at least one individual from each unique COI clade were generated and compared against NCBI's nucleotide BLAST database to provide additional evidence for taxonomical identity and structure. Molecular and morphological data were combined for assignment of species or higher taxonomy. Twelve phylogenetic groups were characterized from the COI and ITS2 sequence data, including the primary vector species Anopheles funestus s.s. and An. gambiae s.s. An unexpectedly large proportion of the field collections were identified as An. coustani and An. sp. 6. Six phylogenetic groups remain unidentified to species-level. Outdoor collections of anopheline mosquitoes in areas frequented by people in Nchelenge, northern Zambia, proved to be extremely diverse. Morphological misidentification and underrepresentation of some anopheline species in sequence databases confound efforts to confirm identity of potential malaria vector species. The large number of unidentified anophelines could compromise the malaria vector surveillance and malaria control efforts not only in northern Zambia but other places where surveillance and control are focused on indoor-foraging and resting anophelines. Therefore, it is critical to continue development of methodologies that allow better identification of these populations and revisiting and cleaning current genomic databases.

Dataset Information

Diel flight activity of wild-caught Anopheles farauti (s.s.) and An. hinesorum malaria mosquitoes from northern Queensland, Australia.

Background

Results

Conclusions

Publications

Diel flight activity of wild-caught Anopheles farauti (s.s.) and An. hinesorum malaria mosquitoes from northern Queensland, Australia.

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