Biochemical Effects of (Umbellifereae) Essential Oil on the Pyrethroid Resistant Strains of (Diptera: Culicidae).

In ongoing screening research for edible plants, essential oil was considered as a potential bioinsecticide with proven antimosquito activity against both the pyrethroid susceptible and resistant strains of . Due to the comparative mosquitocidal efficacy on these mosquitoes, this plant essential oil is promoted as an attractive candidate for further study in monitoring resistance of mosquito vectors. Therefore, the aim of this study was to evaluate the impact of essential oil on the biochemical characteristics of the target mosquito larvae of , by determining quantitative changes of key enzymes responsible for xenobiotic detoxification, including glutathione--transferases (GSTs), - and -esterases (-/-ESTs), acetylcholinesterase (AChE), acid and alkaline phosphatases (ACP and ALP) and mixed-function oxidases (MFO). Three populations of , comprising the pyrethroid susceptible Muang Chiang Mai-susceptible (MCM-S) strain and the pyrethroid resistant Pang Mai Dang-resistant (PMD-R) and Upakut-resistant (UPK-R) strains, were used as test organisms. Biochemical study of larvae prior to treatment with essential oil revealed that apart from AChE, the baseline activity of most defensive enzymes, such as GSTs, -/-ESTs, ACP, ALP and MFO, in resistant UPK-R or PMD-R, was higher than that determined in susceptible MCM-S. However, after 24-h exposure to essential oil, the pyrethroid susceptible and resistant showed similarity in biochemical features, with alterations of enzyme activity in the treated larvae, as compared to the controls. An increase in the activity levels of GSTs, -/-ESTs, ACP and ALP was recorded in all strains of oil-treated larvae, whereas MFO and AChE activity in these mosquitoes was decreased. The recognizable larvicidal capability on pyrethroid resistant . , and the inhibitory effect on AChE and MFO, emphasized the potential of essential oil as an attractive alternative application for management of mosquito resistance in current and future control programs.