Malaria vectors of Papua New Guinea.

Understanding malaria transmission in Papua New Guinea (PNG) requires exact knowledge of which Anopheles species are transmitting malaria and is complicated by the cryptic species status of many of these mosquitoes. To identify the malaria vectors in PNG we studied Anopheles specimens from 232 collection localities around human habitation throughout PNG (using CO(2) baited light traps and human bait collections). A total of 22,970mosquitoes were individually assessed using a Plasmodium sporozoite enzyme-linked immunosorbent assay to identify Plasmodiumfalciparum, Plasmodiumvivax and Plasmodiummalariae circumsporozoite proteins. All mosquitoes were identified to species by morphology and/or PCR. Based on distribution, abundance and their ability to develop sporozoites, we identified five species as major vectors of malaria in PNG. These included: Anophelesfarauti, Anopheleshinesorum (incriminated here, to our knowledge, for the first time), Anophelesfarauti 4, Anopheleskoliensis and Anophelespunctulatus. Anopheleslongirostris and Anophelesbancroftii were also incriminated in this study. Surprisingly, An. longirostris showed a high incidence of infections in some areas. A newly identified taxon within the Punctulatus Group, tentatively called An. farauti 8, was also found positive for circumsporozoite protein. These latter three species, together with Anopheleskarwari and Anophelessubpictus, incriminated in other studies, appear to be only minor vectors, while Anophelesfarauti 6 appears to be the major vector in the highland river valleys (>1500m above sea level). The nine remaining Anopheles species found in PNG have been little studied and their bionomics are unknown; most appear to be uncommon with limited distribution and their possible role in malaria transmission has yet to be determined.

The anopheline fauna of Papua New Guinea.

Surveys for anopheline mosquitoes were conducted throughout the mainland of Papua New Guinea from 1992 to 1998 with the aim of mapping the distribution of the anopheline fauna. Larval collections, adult trap, and human landing collections indicated the presence of seven species (other than those belonging to the Anopheles punctulatus group); these were An. bancroftii, An. annulipes, An, karwari, An. longirostris, An. meraukensis, An. novaguinensis, and An. subpictus. The distribution and ecology of these species is discussed.

Field evaluation of commercial repellent formulations against mosquitoes (Diptera: Culicidae) in Northern Territory, Australia.

Field trials comparing commercially available repellent formulations containing picaridin (1-piperidinecarboxylate acid, 2-(2-hydroxyethyl)-1-methylpropylester) and deet (N,N-diethyl-3-methylbenzamide) against mosquitoes in Northern Territory, Australia, were conducted. Three repellents were compared: Autan Repel containing 9.3% picaridin, RID containing 10% deet, and Bushman Ultra containing 80% deet in a gel. The predominant mosquito species collected were Culex annulirostris Skuse (63.2%), Ochlerotatus normanensis (Taylor) (19.6%), and Anopheles meraukensis Venhuis (8.6%). Autan Repel provided >95% protection against all mosquitoes for 2 h, RID for 7 h, and Bushman for >8 h. Against Cx. annulirostris, Autan Repel provided >95% protection for 5 h, RID for 7 h, and Bushman for >8 h. The study showed that both deet formulations provided significantly better protection against mosquitoes than picaridin (Autan Repel). All 3 repellents provided good protection against Cx. annulirostris, an important vector of arboviruses in Australia.

The effectiveness of light, 1-octen-3-ol, and carbon dioxide as attractants for anopheline mosquitoes in Madang Province, Papua New Guinea.

The effectiveness of light, 1-octen-3-ol (octenol), carbon dioxide (CO2) and a combination of CO2 and octenol were compared as mosquito attractants using encephalitis vector surveillance traps in 2 villages in Madang Province, Papua New Guinea (PNG). Five species were collected, Anopheles koliensis, Anopheles farauti 2, Anopheles farauti 4, Anopheles longirostris, and Anopheles bancroftii. Light alone was not attractive to any of these species, and the attractiveness of octenol alone, though greater than light, was less than that of CO2 or the CO2 + octenol combination. With An. longirostris, the addition of octenol to CO2 resulted in a statistically significant increase in trap numbers; however, for the other species, any increase was not significant, and with An. koliensis and An. bancroftii, trap numbers were actually reduced when the CO2 + octenol bait was used. In PNG, the use of octenol alone would be effective in attracting more anophelines than if light alone was used; however, octenol by itself was not as effective as CO2.

Field evaluation of repellent formulations containing deet and picaridin against mosquitoes in Northern Territory, Australia.

Field efficacy of repellent formulations containing picaridin (1-methyl-propyl 2-(2-hydroxyethyl)-1-piperidinecarboxylate) or deet (N,N,-diethyl-3-methylbenzamide) against mosquitoes in Northern Territory, Australia, was evaluated. The following repellent treatments were evaluated: 19.2% picaridin (Autan Repel Army 20), a solution of 20% deet in ethanol, and 35% deet in a gel (Australian Defense Force [ADF]). The predominant mosquito species were Culex annulirostris Skuse (57.8%), Anopheles merankensis Venhuis (15.4%), and Anopheles bancroftii Giles (13.2%). The protection provided by repellents against Anopheles spp. was relatively poor, with 19.2% picaridin and ADF deet providing >95% protection for only 1 h, whereas 20% deet provided <95% protection at 1 h after repellent application. In contrast, the repellents provided good protection against Cx. annulirostris, with 19.2% picaridin providing >95% protection for 5 h and both deet formulations providing >95% protection for 7 h when collections ceased. This study provides additional field data showing tolerance of Anopheles spp. for repellents. The response of field populations of Cx. annulirostris, an important vector of arboviruses in Australia, to repellents containing deet and picaridin is reported for the first time.

Speciation and distribution of the members of the Anopheles punctulatus (Diptera: Culicidae) group in Papua New Guinea.

Mosquito collections were made throughout the mainland of Papua New Guinea to identify the members of the Anopheles punctulatus group present and to determine their distribution. Identification was made using morphology, DNA hybridization, and polymerase chain reaction (PCR)-RFLP analysis. Nine members of the group were identified: An. farauti s.s. Laveran, An. farauti 2, An. koliensis Owen, and An. punctulatus Dönitz, were common and widespread; An. farauti 4 was restricted to the north of the central ranges where it was common; An. farauti 6 was found only in the highlands above 1,000 m; and An. farauti 3, An. sp. near punctulatus and An. clowi Rozeboom & Knight were uncommon and had restricted distributions. Identification of An. koliensis and An. punctulatus using proboscis morphology was found to be unreliable wherever An. farauti 4 occurred. The distribution and dispersal of the members of the An. punctulatus group is discussed in regard to climate, larval habitats, distance from the coast, elevation, and proximity to human habitation.