Facts are presented which suggest that mosquitoes of the Anopheles barbirostris species group that gave me a very uncomfortable night in 1941, whilst serving with the Volunteer forces, were probably A. donaldi. This species is now known to be a vector of human filariasis and probably malaria. Some of the steps are described by which I was led, sixteen years later, to recognise and later name donaldi as a new species. Reasons are given for thinking that around 1918 A. donaldi was present in some numbers at the railway town of Gemas where malaria was a serious problem. H.P. Hacker made a survey at Gemas in 1918 and though the principal vector was probably A. maculatus, 'umbrosus' and 'barbirostris' were the commonest larvae he found.
Anopheles donaldi Reid, a member of the A. barbirostris species group, is a vector of human filariasis and probably malaria. The discovery of some old specimens of this species, collected in Kuala Lumpur town where it no longer occurs, together with evidence from the literature about past malaria in the town, suggest that donaldi may have played a part in transmitting that malaria.
Blood from most of the residents of a remote village in northern peninsular Malaysia, bordering Thailand, was examined for malaria parasites monthly for 1 year. Plasmodium vivax was the commonest infection, but P. falciparum and mixed infections also occurred. Monthly collections of the malaria vector, Anopheles maculatus showed a positive correlation between mosquito densities and malaria positivity in the human population and a negative correlation with rainfall.
The efficacy of the larvicidal and pupicidal agent (Agnique) MMF was evaluated against larvae of An. arabiensis and Culex (Diptera: Culicidae) under field conditions in Bahary Locality, Khartoum, Sudan. At an applied dosage of 0.25 ml/m2, MMF resulted in 89.4, 79.8 and 88.2% reductions in L3-L4 instars An. arabiensis and 63.5% in Culex larvae (all stages) 24 to 72 hours post-treatment. Pupae were completely eliminated (100%) within 24 hours posttreatment. The earlier instars (L1-L2) of An. arabiensis were more tolerant with a 62.5% reduction at 72 hours post-treatment compared to (L3-L4) instars and pupae. At 7-days post-treatment Agnique gave a 57.5% reduction in L1-L2 and 92.6% in L3-L4 instar larvae of An. arabiensis and 57.3% and 86.4% in Culex larvae and pupae, respectively. We conclude that Agnique can perform effectively against L3-L4 instars and pupae of An. arabiensis for only 1 week, and 3 to 4 days against L1-L2 instars of Culex spp.
Malaria is a major public health problem in Malaysia, particularly in peninsular Malaysia and the state of Sabah. An eradication program started in the states of Sabah and Sarawak in 1961 initially was remarkably successful. A similar but staged program was started in peninsular Malaysia in 1967 and was also quite successful. However, a marked upsurge in incidence in Sabah in 1975-1978 showed that malaria is still a major hazard. The disease leads to great economic losses in terms of the productivity of the labor force and the learning capacity of schoolchildren. The topography, the climate, and the migrations of the people due to increased economic activity are similar in peninsular Malaysia, Sabah, and Sarawak. However, the epidemiologic picture differs strikingly from area to area in terms of species of vectors, distribution of parasitic species, and resistance of Plasmodium falciparum to chloroquine. Likewise, the problems faced by the eradication or control programs in the three regions are dissimilar. Because solutions to only some of these problems are possible, the eradication of malaria in Malaysia is not likely in the near future. However, the situation offers an excellent opportunity for further studies of antimalaria measures.
The WHO adult susceptibility test is in use for insecticide resistance monitoring. Presently, materials are being imported from the Universiti Sains Malaysia, Malaysia and sometimes it is cost prohibitive. As an alternative, we present here a method of bottle bioassay using indigenous material. Different aspects related to the assay were studied and validated in the field. Bottle assay was standardized in the laboratory by using locally sourced material and laboratory-maintained insecticide-susceptible Anopheles stephensi and Aedes aegypti strains against technical grade deltamethrin and cyfluthrin insecticides dissolved in ethanol in a range of different concentrations. The frequency of use of the deltamethrin-coated bottles and shelf-life were determined. Discriminating dose for deltamethrin and cyfluthrin was 10 μg against An. stephensi and 2 μg against Ae. aegypti females. Insecticide-coated bottles stored at 25 to 35 °C can be used for three exposures within 7 days of coating. The study carried out in the laboratory was validated on wild caught An. culicifacies in the states of Odisha and Chhattisgarh against deltamethrin-coated bottles in comparison to WHO adult susceptibility test. Results of the study indicated that deltamethrin-coated bottles were effective up to three exposures within 7 days of coating for field population and 100% mortality was recorded within 35 min as observed in laboratory studies for field collected susceptible population. Also in the WHO adult susceptibility test, 100% knock-down within 35 min and 100% mortality after 24 h holding period were observed in susceptible population, while in it was 50% knock-down in 1 h and 64% mortality after 24 h holding period for resistant population (50% mortality in bottle assay in 60 min). The bottle assay can be used as an alternative to the WHO adult susceptibility test both in the laboratory and field for monitoring insecticide resistance in mosquito vectors using locally sourced material.