Spatio-temporal variations in adult density, abdominal status and indoor resting pattern of Culex quinquefasciatus Say in Panaji, Goa, India

Abstract

Goa is one of the filariasis endemic states of India. However, information on density pattern and resting behavior of Culex quinquefasciatus, say, the principal vector of filariasis in Goa is lacking. Therefore, current longitudinal study was undertaken to investigate these aspects. Panaji was divided into six zones and a total of 240 man hours were spent in 60 fixed catching sites to collect the adult Cx. quinquefasciatus mosquitoes on fortnightly basis from indoor resting sites during 2005-06. The female mosquitoes were classified as unfed, fed, semi-gravid and gravid to ascertain the resting behavior of Cx. quinquefasciatus adults. The data were analysed to evaluate the spatio-temporal variations in adult density, abdominal status and indoor resting sites and linked to meteorological variables like temperature, relative humidity, rainfall and number of rainy days. Cx. quinquefasciatus adults were prevalent perennially in Panaji with highest per man hour density of females (48.6) in February and the lowest density (6.6) in September. Monthly variations in the densities between different months was significant (F=15.3; P less than 0.05). Rainfall significantly influenced the population of Cx. quinquefasciatus (t=2.63; P less than 0.05). Fed group and semi-gravid group showed a strong correlation with the relative humidity (P less than 0.05), rain fall (P less than 0.05) and number of rainy days (P less than 0.05). 62.4 per cent of females and 65.1 per cent of males preferred to rest on hanging objects. Spatio-temporal variations in the number of Cx. quinquefasciatus females and males resting on different sites and also the variations in different sites (P less than 0.05) were significant. The density of female Cx. quinquefasciatus encountered in all the months was higher than the estimated tolerated level of density of 34 per ten man hours up to which there is no risk of filariasis transmission.