Determination of insecticide susceptibility in Culex quinquefasciatus Say adults by rapid enzyme microassays.

Rapid enzyme microassays for the detection of resistance due to organophosphate and carbamate in individual field-collected strains of Culex quinquefasciatus adults were conducted. These tests allowed accurate differentiation by eye, on the basis of color changes of susceptible and resistant individuals. Two separate tests were conducted for the biochemical assays. In the insensitive acetylcholinesterase (AChE) test, acetylthiocholine iodide (ACTH) and 5, 5-dithiobis-(2-nitrobenzoic acid) (DTNB) were used as substrate and coupling agent respectively. The resulting yellow chromophore indicated AChE activity