Evaluation the Oviposition Behaviour of Aedes Aegypti and Ae. Albopictus Mosquitoes; Main and Secondary Vector for Dengue Transmission in Sri Lanka under Laboratory Conditions

Abstract

Studies on the oviposition behavior of Aedes albopictus and Ae. aegypti are critical for effective controlling of dengue vector breeding. However, less attention has been drawn on such aspects of vector biology and bionomics in Sri Lanka. Therefore, the objective of the current study was to evaluate the oviposition behavior of dengue vectors under laboratory conditions. Ovitraps with different sizes, colours, sources of water, sodium chloride (NaCl) concentration (0.2, 0.5, 1, 2 and 3%) and presence and absence of larvae were kept within separate cages of batches of 1000 Ae. albopictus and Ae. aegypti with (1:1, male: female ratio). Female mosquitoes were allowed to lay eggs and the number of eggs laid in different ovitraps were enumerated. ANOVA and cluster analysis were used to investigate the significance in the variations among oviposition behaviours. The mean number of eggs laid by both Ae. albopictus and Ae. aegypti increased with the increasing size of the ovitraps. Ae. albopictus indicated the highest mean number of eggs in 0.2% of NaCl than that of distilled water, while the egg laying preference reduced with the increasing salinity for both species. Drain water with low dissolved oxygen level (0.43 ± 0.12 mg/l) was the preferred water source for both species and indicated a significantly high oviposition rate in ovitraps with larvae. Black colour ovitraps attracted the majority of the gravid females, while white was least preferred. There were no significant variations among oviposition behaviors of Ae. albopictus and Ae. aegypti under laboratory conditions. Back coloured ovitraps were the preferred breeding place.