|Date||December 14, 2021|
|Title||TARGET-SITE MUTATION OF RDL GENE AND INSECTICIDE SUSCEPTIBILITY IN FIPRONIL- AND PYRETHROID-RESISTANT AEDES AEGYPTI MOSQUITOES FROM NAKHON PATHOM AND KANCHANABURI PROVINCES|
Introduction: Long-term and intensive applications of various insecticides in mosquito control have inevitably led to the development of resistance mechanisms. Rdl (Resistant to dieldrin) gene is the important target for dieldrin and fipronil. It is therefore important to investigate the presence of Rdl mutation and insecticide susceptibility in pyrethroid-resistant Ae. aegypti mosquitoes, the vector of dengue and Zika, from Nakhon Pathom and Kanchanaburi provinces. Methods: The pyrethroid-resistant female mosquitoes were exposed to 0.14% fipronil (phenylpyrazole), 1.00% fenitrothion (organophosphate) and 0.34% fenobucarb (carbamate) by WHO susceptibility test. Genomic DNA extracted from individual fipronil-resistant females was PCR amplified and then subjected to DNA sequencing. Results: 0.14% fipronil provided 94.00±5.20% and 96.00±3.30% mortality rates in the mosquitoes from Nakhon Pathom and Kanchanaburi provinces, respectively. A substitution of alanine at 302 with serine, A302S, was detected in the mosquitoes from Nakhon Pathom and Kanchanaburi provinces at mutation frequencies of 0.33 (2/6 sequences) and 0.25 (1/4 sequences), respectively. However, 1.00% fenitrothion and 0.34% fenobucarb gave a 100% mortality rate in the mosquitoes from all 2 provinces. The mean mortality rates of mosquitoes were significantly different among insecticides (p<0.05). Conclusion: The target-site mutation of Rdl gene, A302S, was present in the fipronil- and pyrethroid-resistant mosquitoes from all 2 provinces. However, the mosquitoes were completely susceptible to 1.00% fenitrothion and 0.34% fenobucarb. It suggests that those insecticides should be used sparingly and integrated with the safe mosquito control measures. The data on insecticide susceptibility test were reported to Tambon Health Promoting Hospitals in the study areas for effective mosquito control.
|Presenter||Dr.Jakkrawarn Chompoosri National Institute of Health, Department of Medical Sciences, Nonthaburi 11000, Thailand|