Reliability of light trap sampling for Anopheles fluviatilis, a vector of malaria

The utility of light traps for sampling Anopheles fluviatilis, the major malaria vector in the hill tracts of Koraput district, Orissa, was assessed. A modified version of the CDC miniature light trap was used in the study. The data generated from light trap collections were analysed and compared with daytime resting, man-biting and night resting collections carried out in parallel. The number per trap recorded in cattle sheds was significantly higher than that recorded in human dwellings. A similar pattern was observed in hand catches of indoor resting population though the difference was not significant. The density recorded from light traps over time was found to have a significant positive linear association with corresponding indoor (r = 0.625; p = 0.0019) as well as outdoor (r = 0.603; p = 0.0029) diurnal resting densities. The proportion with different gonotrophic stages varied significantly between different types of collections. The age structure of A. fluviatilis did not differ significantly with the types of collection. As the light trap catches reflect seasonal fluctuations in the diurnal resting collections, they can justifiably be used in monitoring the relative density of A. fluviatilis in the place of cumbersome hand catch methods. Other uses of light traps are also discussed.