RESUMO
This study was conducted in four strains of Aedes aegypti mosquitoes to evaluate the enzymatic activity profiles in the city of Mossoró, Rio Grande do Norte, and correlate them with biochemical mechanisms of resistance to insecticides. Mosquitos were used to quantify the following detoxification enzymes: Mixed-Function Oxidase (MFO), PNPA-esterase (PNPA-EST), and Acetylcholinesterase (AChE). The profiles were compared statistically with profiles from the Rockefeller strain, through the Kruskal-Wallis test and Dunn's multiple comparisons (p < 0.05). The 99 percentile of the values of enzyme activity from the reference strain was calculated for each enzyme, and the percentage of individuals above the 99 percentile was quantified. The enzyme activities were classified as "Unchanged" (< 15%), "Identified change" (> 15% and < 50%), and "Substantially changed" (> 50%). The statistical analysis revealed significant differences in the MFO and AChE profiles, which are fundamental in the determination of profiles of resistance to insecticides. Three populations were classified as "Substantially changed" for MFO. The altered enzymatic activity showed that the changes could have an important role in exposing resistance to insecticides.
Assuntos
Aedes/enzimologia , Resistência a Inseticidas , Animais , Brasil , InseticidasRESUMO
Abstract This study was conducted in four strains of Aedes aegypti mosquitoes to evaluate the enzymatic activity profiles in the city of Mossoró, Rio Grande do Norte, and correlate them with biochemical mechanisms of resistance to insecticides. Mosquitos were used to quantify the following detoxification enzymes: Mixed-Function Oxidase (MFO), PNPA-esterase (PNPA-EST), and Acetylcholinesterase (AChE). The profiles were compared statistically with profiles from the Rockefeller strain, through the Kruskal-Wallis test and Dunn's multiple comparisons (p < 0.05). The 99 percentile of the values of enzyme activity from the reference strain was calculated for each enzyme, and the percentage of individuals above the 99 percentile was quantified. The enzyme activities were classified as “Unchanged” (< 15%), “Identified change” (> 15% and < 50%), and “Substantially changed” (> 50%). The statistical analysis revealed significant differences in the MFO and AChE profiles, which are fundamental in the determination of profiles of resistance to insecticides. Three populations were classified as “Substantially changed” for MFO. The altered enzymatic activity showed that the changes could have an important role in exposing resistance to insecticides.
Resumo Este estudo foi realizado em quatro cepas de mosquitos Aedes aegypti da cidade de Mossoró, Rio Grande do Norte, com o intuito de avaliar os perfis de atividade enzimática e correlacioná-los com os mecanismos bioquímicos de resistência a inseticidas. Mosquitos foram utilizados para quantificar as seguintes enzimas de detoxificação: oxidase de Função Mista (MFO), PNPA-esterase (PNPA-EST) e acetilcolinesterase (AChE). Os perfis das populações foram comparados estatisticamente com os da cepa Rockefeller por meio do teste de Kruskal-Wallis e do de comparações múltiplas de Dunn (p < 0,05). O percentil 99 dos valores de atividade enzimática da cepa referência foi calculado para cada enzima, e o percentual de indivíduos acima desse valor foi quantificado. As atividades enzimáticas foram classificadas como “Inalterada” (< 15%), “Alteração Identificada” (> 15% e < 50%), e “Substancialmente Alterada” (> 50%). A análise estatística revelou diferenças significativas nos perfis de MFO e AChE, que são fundamentais na determinação de perfis de resistência a inseticidas. Três populações foram classificadas como “Substancialmente Alteradas” para MFO. Os níveis alterados de atividade enzimática demonstram que essa mudança pode desempenhar um importante papel na resistência a inseticidas.