Development of the major arboviral vector Aedes aegypti in urban drain-water and associated pyrethroid insecticide resistance is a potential global health challenge

Abstract

Background Aedes aegypti were found developing in the water in open public drains (drain-water, DW) in Jaffna city in northern Sri Lanka, a location where the arboviral diseases dengue and chikungunya are endemic. Methods Susceptibilities to the common insecticides dichlorodiphenyltrichloroethane (DDT), malathion, propoxur, permethrin and deltamethrin and activities of the insecticide-detoxifying enzymes carboxylesterase (EST), glutathione S-transferase (GST) and monooxygenase (MO) were compared in adult Ae. aegypti developing in DW and fresh water (FW). Results DW Ae. aegypti were resistant to the pyrethroids deltamethrin and permethrin, while FW Ae. aegypti were susceptible to deltamethrin but possibly resistant to permethrin. Both DW and FW Ae. aegypti were resistant to DDT, malathion and propoxur. Greater pyrethroid resistance in DW Ae. aegypti was consistent with higher GST and MO activities. Conclusions The results demonstrate the potential for insecticide resistance developing in Ae. aegypti adapted to DW. Urbanization in arboviral disease-endemic countries is characterized by a proliferation of open water drains and therefore the findings identify a potential new challenge to global health.

Resistance to commonly used insecticides and underlying mechanisms of resistance in Aedes aegypti (L.) from Sri Lanka

“…Resistance to commonly used insecticides has been investigated in brackish water breeding as well as in drain-water breeding Ae aegypti mosquitoes in Sri Lanka [24,25]. Drain-water breeding mosquitoes were reported to be resistant to pyrethroids (deltamethrin and permethrin) and to show higher GST and MO activities [24].…”

“…A study analyzing the susceptible status of the drain-dwelling Ae. aegypti in Sri Lanka reported that mosquitoes with elevated activities of GST and monooxygenases were resistant to pyrethroids, malathion and propoxur [24]. Aedes aegypti collected from brackish water breeding sites were reported as resistant to propoxur (0.1%), whereas no significant differences were observed when these brackish water breeders were compared with fresh water breeders for permethrin (0.25%) and malathion (4%) [25].…”

“…Several studies have reported the susceptibility status of Ae. aegypti mosquitoes breeding in drain water and brackish water in Sri Lanka [24,25]. A study analyzing the susceptible status of the drain-dwelling Ae.…”

Anopheline bionomics, insecticide resistance and transnational dispersion in the context of controlling a possible recurrence of malaria transmission in Jaffna city in northern Sri Lanka

“…The ability of Ae. aegypti to develop in polluted water in surface drains in Jaffna city is associated with greater resistance to pyrethroids [43]. Elucidating biological changes in anophelines associated with similar adaptation to salinity and pollution in Jaffna city can further help understand the adaptability of different mosquitoes to anthropogenic environmental changes.…”

“…Resistance to deltamethrin in Ae. aegypti developing in polluted drain water in Jaffna city was suggested to be caused by adaptation to cope with organic pollutants in drain water and possibly the common use of pyrethroids to control adult mosquitoes and other insect pests in Jaffna [43]. The same factors may also be responsible for deltamethrin resistance in Jaffna city anophelines.…”