Breeding preference of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Galle District, Sri Lanka

Abstract

Aedes aegypti and Aedes albopictus are main vectors of Dengue (DF) and Dengue Haemorrhagic (DHF) Fever in Sri Lanka. Both species are known to breed in microhabitats including water-filled containers, yet whether there is any breeding preference linked to features of containers/ microhabitats has not been addressed. Present study was conducted to find out breeding preference of the two Aedes species by estimating relative larval abundance in selected artificial and natural microhabitats. Nine larval surveys were conducted from January to October in 2017, and 1069 containers/ microhabitats were randomly sampled from three localities representing urban (n = 346), suburban (n = 367), and rural areas (n= 356) of Galle District. A total of 552 (51.63%) containers/ microhabitats were positive for both Ae. aegypti and Ae. albopictus larvae. Both species preferred artificial containers (90.57%) (including rubber tyres: 17.82%, plastic cups: 17.09%, and metal cups: 9.82%) than natural containers (9.43%) (including plant axils, coconut shells and wood caves). Analysis of percentage abundance of larvae revealed that both species had similar preference for black-coloured containers (47.98% for Ae. aegypti and 37.32 % for Ae. albopictus). Both species were abundant in containers having water level height less than 10 cm (Ae. aegypti 77.57% and Ae. albopictus70.11%) and containers with 50-100 ml of water (Ae. aegypti 29.28% and Ae. albopictus 41.79%). Their abundance increased with the presence of leaf litter in the containers (Ae. aegypti 80.69% and Ae. albopictus 73.77%). For both species, preferred water temperature was 31 ± 0.3oC (Ae. aegypti 58.23% and Ae. albopictus 61.21%) while preferred mean water pH was 7.44 ± 0.04 (Ae. aegypti 56.84% and Ae. albopictus 52.46%). Characteristic features such as the presence of leaf litter, pH and temperature of the logged water within the containers/ microhabitat may play an important role on the abundance of these two Aedes vector mosquito species.