The ecology and behavior of most of the 11 known members of the Anopheles punctulatus group remain unresolved and only the morphologic species An. farauti, An. koliensis, and An. punctulatus are known as vectors of malaria in Papua New Guinea. Of 1,582 mosquitoes examined morphologically, 737 were identified as An. farauti s.l., 719 as An. koliensis, and 126 as An. punctulatus. All specimens identified morphologically as An. punctulatus were shown to be An. punctulatus by polymerase chain reaction-restriction fragment length polymorphism analysis, but the An. farauti and An. koliensis morphotypes consisted of three or more species including An. farauti s.s., An. farauti No. 2, and An. farauti No. 4. The biting cycles and role in malaria transmission of some of these species are described here for the first time. We also show evidence that An. koliensis could be a sub-complex of two or more species. The epidemiologic implications of our findings are discussed.

The mosquito sampling efficiency of CDC (Centers for Disease Control) miniature light traps hung adjacent to mosquito nets, was compared with that of both indoor and outdoor human-bait collections in ten villages in the Wosera area of Papua New Guinea. The most frequently collected anopheline in the matched indoor and light trap samples was Anopheles koliensis Owen, followed by A. punctulatus Dönitz, A. karwari (James), A. farauti Laveran (sensu lato), A. longirostris Brug and A. bancroftii Giles. All species were much less frequent in the light traps than in landing catches. The hypothesis that the numbers of mosquitoes in light traps are proportional to human landing catches was examined using regression models that allowed for sampling error in both entomological measurements. Light traps under-sampled A. punctulatus and A. farauti s.l. at high densities. The models indicated that the ratio of light trap to landing catch females of A. koliensis and A. karwari increased with increasing mosquito density. Light trap catches of A. longirostris were proportional to indoor landing rates but when outdoor landing rates were high this species was under-sampled by light traps. Numbers of A. bancroftii in light traps were found to be proportional to those in outdoor landing catches, but were negatively related to those attempting to bite indoors. Circumsporozoite positivity rates for both Plasmodium falciparum Welch and P. vivax (Grassi & Feletti) in A. punctulatus and A. farauti s.l. were significantly higher in light trap collections than in either indoor or outdoor landing catches, suggesting that light traps may selectively sample older mosquitoes of these species.

Relationships between area coverage with insecticide-free bednets and prevalence of Plusvv~udiumfalcipanrm were investigated in 7 community-based surveys over a 33-month period in 1990-93 in 6 villages in the Wosera area of Papua New Guinea. Spatial patterns in circumsporozoite rates for I? jalciparum, I? oivax isomorphs K210 and K247, and i? mah-iae, and the proportions of mosquito blood meals positive for specific human, goat, cat, dog and pig antigens were determined using ELISAs. I? fakiparulm prevalence in humans was better explained by bednet coverage in the immediate vicinity than by personal protection alone. Circumsporozoite rates for both P jalci@rum and I? &ax were also inversely related to coverage with bednets. There was some increase in zoophagy in areas with high coverage, but relatively little effect on the human blood index or on overall mosquito densities. In this setting, protracted use ofuntreated bednets apparently reduces sporozoite rates, and the associated effects on prevalence are greater than can be accounted for by personal protection. Even at high bednet coverage most anophe1ines feed on human hosts, so the decreased sporozoite rates are likely to be largely due to reduction of mosquito survival. This finding highlights the importance of local vector ecology for outcomes of bednet programmes and suggests that area effects ofuntreated bednets should be reassessed in other settings,

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Abundance of anophelines in 10 villages in the Wosera area of Papua New Guinea was monitored during 1990-1993 anophelines collected in 1,276 paired indoor and outdoor landing catches, 40.4% were Anopheles koliensis Owen, 36.7% An. punctulatus Donitz, 14.3% Art. karwari (James), 4.9% An. farauti s.l. Laveran, 3.1% An. longirostris Brug, and 0.7% An. bancroftii Giles. Maps of average indoor biting rates were produced using a Bayesian conditional autoregressive model which allowed for heterogeneities in sampling effort over time and space. Differences in spatial distributions among species were observed among and within villages and were related to the distribution of larval habitats and vegetation. Abundance of An. punctulatus and An. koliensis decreased with distance from the main waterway and probably from a sago swamp forest at 6 villages in North Wosera. Abundance of An. punctulatus was associated negatively with those of An. farauti s.l., An. longirostris, and An. bancroftii. The latter 3 species also had relatively low ratios of indoor-to-outdoor biting rates, and earlier biting times than An. punctulatus. Human blood indices of at least 0.79 were observed for all species except An. bancroftii. Abundance of all 6 species was correlated temporally with recent rainfall, but An. koliensis, An. kanvari, and An. longirostris showed greater temporal variability than the other species. An. punctulatus and An. koliensis tended to occur together in time and space (index of association, / = 0.85). Weaker associations were seen between An. farauti s.l. and An. longirostris (I = 0.44) and An. koliensis and An. kanvari (I = 0.34). The most frequently collected species occurred together and were concentrated near the Amugu river; the remaining species tended to occur together but in different parts of the Wosera area. The importance of understanding ecological requirements of the different Anopheles vectors and their association with key household and landscape features are discussed in relation to malaria transmission and control.