Aedes Mosquito Survey within the Premises of University Sri Jayewardenepura to Determine Its Population Density and of Seasonal Shift in Relative Abundance

Abstract

The Premises of the University of Sri Jayewardenepura was surveyed in the month of May for possible breeding habitats of mosquitoes which were mapped out and the immature stages of collected were identified. Subsequently investigations were made by placing ovitraps within the University premises from June to November 2008, to determine the abundance of Aedes aegyp ti and Aedes albopictus detected during the previous survey in the month of May. An Ae.aegypti positive container was detected only once in all the indoor and outdoor container observed and no Ae.aegypti positive ovitrap was recorded during the study period .. The Ovitrap Index (01) for Ae.albopictus was calculated monthly. Breeding of Ae.albopictus was found in both indoor (Mean Monthly 01 =13.3) and out door containers (Mean Monthly 01 35.3). During the dry season the rainfall recorded a monthly range of 45.6 mm to 152.6mm. The larval population of Ae.albopictus remained low during this period with an 01 range from 0 to 12.5. However, during the rainy season which showed a monthly range of 294.9mm to 414.4mm, the 01 increased exponentionally (01 ranges from 13.3-80). In the month of September, Ae.albopictus were recorded in indoor ovitraps too (01=13.3), indicating its ability to replace the breeding places of Ae.aegypti, under certain environmental conditions. The monthly dengue incidence reported from the neighboring area declined in the month of August and started to increase again in the month of September. The ecological conditions in theses areas are very much similar to those within the University premises. The 01 values of dengue vector mosquito species could be utilized to indicate a potential increase in the dengue incidence.