A method for distinguishing the important malaria vectors Anopheles dirus and An. cracens (Diptera: Culicidae) based on antennal sensilla of adult females

@#Some species of the Anopheles dirus species complex are considered to be highly competent malaria vectors in Southeast Asia. Anopheles dirus is the primary vector of Plasmodium falciparum and P. vivax while An. cracens is the main vector of P. knowlesi. However, these two species are difficult to distinguish and identify based on morphological characters. Hence, the aim of this study was to investigate the potential use of antennal sensilla to distinguish them. Large sensilla coeloconica borne on the antennae of adult females were counted under a compound light microscope and the different types of antennal sensilla were examined in a scanning electron microscope. The antennae of both species bear five types of sensilla: ampullacea, basiconica, chaetica, coeloconica and trichodea. Observations revealed that the mean numbers of large sensilla coeloconica on antennal flagellomeres 2, 3, 7, 10 and 12 on both antennae of both species were significantly different. This study is the first to describe the types of antennal sensilla and to discover the usefulness of the large coeloconic sensilla for distinguishing the two species. The discovery provides a simple, reliable and inexpensive method for distinguishing them.

Some observations on sympatric populations of the malaria vectors Anopheles leucosphyrus and Anopheles balabacensis in a village-forest setting in South Kalimantan.

Human bait collections of biting anopheline mosquitoes were made on five consecutive nights during September 1986 in a remote village located in a heavily forested area of South Kalimantan, Indonesia. Anopheles leucosphyrus and An. balabacensis comprised 97.7% of the total number of specimens collected outside houses in the village. Anopheles balabacensis were slightly fewer in total numbers than leucosphyrus. Mosquitoes were collected simultaneously in the village and the forest on two nights. The numbers of leucosphyrus and balabacensis biting in the forest were small in comparison with the populations encountered in the village. Approximately 75% of the specimens were checked individually for sporozoite infections using ELISA for P. falciparum and P. vivax. Sporozoites of P. falciparum were detected in one specimen of leucosphyrus and one of balabacensis. The sporozoite infection rate was 1.0% for leucosphyrus and 1.3% for balabacensis.