Preliminary study on surveillance and resistance status of Aedes aegypti against various insecticides in Sunda Islands, Indonesia / Amirah Haziqah Rashid

Aedes mosquitoes are well known as the vector of dengue fever (DF) and dengue hemorrhagic fever (DHF) which are a major health concern in Indonesia. Little to none study was done on the resistance status of adulticides and larvicides against the field population across Indonesia. Thus, in this study, ovitrap surveillance was conducted to determine the abundance of dengue vectors in fourteen study sites across eight provinces located in the Sunda Islands, Indonesia. High ovitrap indices up to 70% and 90% were obtained from indoor and outdoor areas, respectively. The mean numbers of Ae. Aegypti and Ae. albopictus larvae ranged from 0.13 to 14.50 and 0.10 to 18.60, respectively. Mixed infestation (< 10%) and interchange of breeding habitat preferences of Ae. albopictus and Ae. aegypti were also observed in the present study. Field-collected and reference strains of Ae. aegypti larvae were tested against diagnostic dosage of 8 larvicides which belong to organophosphates and organochlorines. This study shows that Ae. aegypti larvae from Padang, Samarinda, Flores and Timor were susceptible to both fenitrothion and dieldrin (mortality ≥ 98%). Six out of 10 field strain of Ae. aegypti larvae were resistant (< 80% mortality) against fenthion, whilst Kuningan, Samarinda, Sumba and Timor exhibited some development of resistance (mortality between 80-98%). All field-collected Ae. aegypti larvae were resistant against diagnostic dosages of chlorpyrifos, malathion, temephos and DDT with mortality ranging from 0% to 74.67%. Field adult Ae. aegypti exhibited various knockdown rate, ranging from 0.00 - 100.00%, 0.00 - 44.00%, 0.00 - 6.7% and 0.00% for pyrethroids, organophosphates, carbamates and organochlorines respectively. Overall, mortality of adult Ae. aegypti ranges from 6.67 to 100.00% were recorded across the Indonesian populations. There were significant correlations between the mortality rates of lambda-cyhalothrin and permethrin (r = 0.733, p = 0.016); lamda-cyhalothrin and deltamethrin (r = 0.83, p = 0.003); lambda-cyhalothrin and etofenprox (r = 0.936, p < 0.01); dieldrin and DDT (r = 0.701, p = 0.024); and DDT and deltamethrin (r = 0.69, p = 0.027). This showed the existence of cross resistance within the pyrethroids, organochlorines and, between pyrethroids and DDT. This study revealed that the Ae. aegypti were resistant to most insecticides tested. However, there are insecticides to which Ae. aegypti are also still susceptible and are not frequently used in Indonesia as vector control. Thus, rotating among the insecticides could be an alternative way in controlling the resistance of using a single insecticide