Pattern of Human-biting Activity of Aedes aegypti L. and Aedes albopictus Skuse in a Garden Locale from City of Kolkata, India

In a yearlong study, centering a garden in Kolkata possible competitive displacement of populations of Ae. aegypti and Ae. albopictus was suggested (Gilotra et al., 1967). After about 20 years, a comparative 24 h man-biting activity of Ae. aegypti and Ae. albopictus mosquitoes was investigated in the same garden from September 1986 to August 1987. During day light hours, altogether 248 Ae. aegypti mosquitoes were collected off human baits, of which 77 (31.04%) and 171 (68.95%) off indoor and outdoor baits respectively. The corresponding figures for Ae. albopictus were 867 [183 (21.10%) at indoors and 684 (78.89%) at outdoors]. Both species of mosquitoes were found to be attracted to human baits both at indoor and outdoor, throughout the day, with the peak hour of biting activity of Ae. aegypti between 8 and 9 a.m. [60 (24.19%)]followed by another peak during 5-6 p.m. [40 (16.13%)]. Peak activity of Ae. albopictus was observed between 5 and 6 p.m. (135 i.e. 15.5%). For both the species the peak biting activity was found in the month of July [ Ae. aegypti , 52 (20.96%) and Ae. albopictus , 264 (30.4%)]. Altogether 36 and 13 Ae. aegypti were caught off man-baits at indoors and outdoors respectively beyond day light hours and the corresponding figures for Ae. albopictus were 56 and 34 respectively. This infers a possible competitive displacement of Ae. aegypti populations by the populations of Ae. albopictus.