Insecticide resistance and, efficacy of space spraying and larviciding in the control of dengue vectors Aedes aegypti and Aedes albopictus in Sri Lanka

• Published in: Pesticide biochemistry and physiology 2013-09, Vol.107 (1), p.98-105
• Main Authors: Karunaratne, S.H.P.P., Weeraratne, T.C., Perera, M.D.B., Surendran, S.N.
• Format: Article
• Language: English
• Subjects: Aedes - drug effects; Aedes - metabolism; Animals; Carboxylesterase - metabolism; DDT - pharmacology; Dengue - prevention & control; Dengue vectors; Female; Fogging; Glutathione Transferase - metabolism; Insect Proteins - metabolism; Insect Vectors - drug effects; Insect Vectors - metabolism; Insecticide Resistance; Insecticides - pharmacology; Larva - drug effects; Larva - metabolism; Malathion - pharmacology; Mixed Function Oxygenases - metabolism; Mosquito Control - methods; Propoxur - pharmacology; Pyrethrins - pharmacology; Sri Lanka; Temefos - pharmacology; Temephos
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/j.pestbp.2013.05.011

Changes in the percentage mortalities of Ae. aegypti and Ae. albopictus larvae after exposing to temephose for a 24h period in water storage cement tanks in households in the field (temephose concentration was initially adjusted to 1ppm but later diluted with the usage). [Display omitted] •Both Aedesaegypti and Aedesalbopictus had comparable cross-resistance spectra.•DDT/permethrin resistance and malathion/propoxur susceptibility were observed.•Malathion carboxylesterase mechanism has resulted moderate malathion resistance.•No elevated monooxygenase amounts suggesting a ‘kdr’ based pyrethroid resistance.•Deltacide is more effective in fogging and temephos is effective as a larvicide. Unprecedented incidence of dengue has been recorded in Sri Lanka in recent times. Source reduction and use of insecticides in space spraying/fogging and larviciding, are the primary means of controlling the vector mosquitoes Aedes aegypti and Ae. albopictus in the island nation. A study was carried out to understand insecticide cross-resistance spectra and mechanisms of insecticide resistance of both these vectors from six administrative districts, i.e. Kandy, Kurunegala, Puttalam, Gampaha, Ratnapura and Jaffna, of Sri Lanka. Efficacy of the recommended dosages of frequently used insecticides in space spraying and larviciding in dengue vector control programmes was also tested. Insecticide bioassay results revealed that, in general, both mosquito species were highly resistant to DDT but susceptible to propoxur and malathion except Jaffna Ae. aegypti population. Moderate resistance to malathion shown by Jaffna Ae. aegypti population correlated with esterase and malathion carboxylesterase activities of the population. High levels of acetylcholinesterase (AChE) insensitivity in the absence of malathion and propoxur resistance may be due to non-synaptic forms of AChE proteins. Moderate pyrethroid resistance in the absence of high monooxygenase levels indicated the possible involvement of ‘kdr’ type resistance mechanism in Sri Lankan dengue vectors. Results of the space spraying experiments revealed that 100% mortality at a 10m distance and >50% mortality at a 50m distance can be achieved with malathion, pesguard and deltacide even in a ground with dense vegetation. Pesguard and deltacide spraying gave 100% mortality up to 50m distance in open area and areas with little vegetation. Both species gave >50% mortalities for deltacide at a distance of 75m in a dense vegetation area. Lar