Insecticide resistance compromises the control of Aedes aegypti in Bangladesh

• Published in: Pest management science Vol. 79; no. 8; pp. 2846 - 2861
• Main Authors: Al‐Amin, Hasan Mohammad, Gyawali, Narayan, Graham, Melissa, Alam, Mohammad Shafiul, Lenhart, Audrey, Hugo, Leon E, Rašić, Gordana, Beebe, Nigel W, Devine, Gregor J
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.08.2023; Wiley Subscription Services, Inc
• Subjects: Aedes - genetics; Aedes aegypti; Animals; Bangladesh; Bioassays; Colonies; Culicidae; Deltamethrin; Dengue; Dengue fever; Esterases; Glutathione; Homozygotes; Host searching behavior; Insecticide resistance; Insecticide Resistance - genetics; Insecticides; Insecticides - pharmacology; kdr; metabolic resistance; Mortality; Mosquito Vectors; Mosquitoes; operational control; Permethrin; Pest control; Pesticide resistance; Pyrethrins - pharmacology; Pyrethroids; Vaccines; Vector-borne diseases; Vectors; Bangladesh; kdr; pyrethroids; Aedes aegypti; insecticide resistance; metabolic resistance; operational control
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.7462

BACKGROUND With no effective drugs or widely available vaccines, dengue control in Bangladesh is dependent on targeting the primary vector Aedes aegypti with insecticides and larval source management. Despite these interventions, the dengue burden is increasing in Bangladesh, and the country experienced its worst outbreak in 2019 with 101 354 hospitalized cases. This may be partially facilitated by the presence of intense insecticide resistance in vector populations. Here, we describe the intensity and mechanisms of resistance to insecticides commonly deployed against Ae. aegypti in Dhaka, Bangladesh. RESULTS Dhaka Ae. aegypti colonies exhibited high‐intensity resistance to pyrethroids. Using CDC bottle assays, we recorded 2–24% mortality (recorded at 24 h) to permethrin and 48–94% mortality to deltamethrin, at 10× the diagnostic dose. Bioassays conducted using insecticide–synergist combinations suggested that metabolic mechanisms were contributing to pyrethroid resistance, specifically multi‐function oxidases, esterases, and glutathione S‐transferases. In addition, kdr alleles were detected, with a high frequency (78–98%) of homozygotes for the V1016G mutation. A large proportion (≤ 74%) of free‐flying and resting mosquitoes from Dhaka colonies survived exposure to standard applications of pyrethroid aerosols in an experimental free‐flight room. Although that exposure affected the immediate host‐seeking behavior of Ae. aegypti, the effect was transient in surviving mosquitoes. CONCLUSION The intense resistance characterized in this study is likely compromising the operational effectiveness of pyrethroids against Ae. aegypti in Dhaka. Switching to alternative chemical classes may offer a medium‐term solution, but ultimately a more sustainable and effective approach to controlling dengue vectors is required. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. Phenotypic characterization of insecticide resistance was conducted using an adaptation of the CDC bottle bioassay on 3‐ to 5‐day‐old, non‐blood‐fed female F1 mosquitoes.