Enzymatic profile of Aedes albopictus upon continuous exposure to insecticides throughout Penang, Malaysia

This study presents the insecticide susceptibility status and enzymatic activity profiling of Aedes albopictus mosquitoes involving glutathione s-transferase (GST), esterase, cytochrome P450 (Cyt P450) and acetylcholinesterase (AChE) from all the five districts of Penang, Malaysia with high incidence of dengue cases. World Health Organisation (WHO) bioassay and biochemical analysis were conducted and compared between field and susceptible strains to distinguish the role of enzymatic activities on xenobiotic exposure in Penang, Malaysia. WHO bioassay indicated that resistance to malathion was relatively lower (1.62 to 2.22-fold increase) compared to permethrin (2.26 to 2.74-fold increase). Total protein content of larvae from Lebuh Bukit Kecil (BK) strain (South West) was the most elevated among the field strains. The total protein content of larvae from all the districts except Lebuh Nipah (LN) strain (North East) were elevated and statistically significant (p˂0.05) upon comparison with the susceptible strain. Enzymatic activities of α-esterase and β-esterase were the highest in larvae collected from all the districts in Penang and displayed the most significant elevation (p˂0.05) in their respective specific enzyme activities followed by GST and Cyt P450. The results provide a better understanding of the current resistance phenomenon and enzymatic activity of the test enzymes in Ae. albopictus mosquitoes upon xenobiotic challenge. This information would be useful for effective insecticide-based management of the vector.