Digestive and energy metabolism enzymes from pyrethroid resistant and susceptible populations of maize weevil / Enzimas de metabolismo energético e digestivo em populações de caruncho-do-milho resistentes e susceptível a piretróides

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Studies on Sitophilus zeamais populations of distinct insecticide susceptibility suggest higher efficiency in mobilizing energy in some resistant populations, making possible the production of their defense apparatus against insecticide, without impairing their reproductive performance. This efficiency can be the result of a high carbohydrates and proteins accumulation originated from a high digestive rate. To test this hypothesis, a series of enzymatic assays with energy metabolism and digestive enzymes was carried out in Jacarezinho and Juiz de Fora resistant populations, and in the Sete Lagoas susceptible population. In addition, concentration-response bioassays and respirometric tests were carried out in the same populations. The Jacarezinho population showed a respiration rate significantly higher than the others. Among the energy metabolism enzymes, only trehalase and lypase showed significant differences among the three populations, showing higher activity in the Juiz de Fora population. Trehalase also follows the Michaelis-Menten kinetic model and the KM and Vmax kinetic parameters were estimated. The results obtained in the assays with glycosidase and amylase (sugar hydrolysis) indicate that only amylase showed a significant difference in activity among populations, with higher value for Jacarezinho. Among digestive enzymes, only total proteinase did not differ significantly among the three populations. Juiz de Fora and Jacarezinho showed the higher activities of serine-proteinase (amydolitic), cysteineproteinase and cellulase. However, the highest activity of serine-proteinase (esterolytic) was exhibited only by the Juiz de Fora population. Among the enzymes for food access, pectin lyase did not show significant difference in activity among the three populations. Sete Lagoas and Juiz de Fora showed higher polygalacturonase activity. Serineproteinase (amydolitic and esterolytic), cysteine-proteinase and cellulase were the enzymes that contributed the most to the divergence among the populations.

ASSUNTO(S)

sitophilus zeamais insecticide resistance resistência a inseticidas enzimas entomologia agricola enzymes physiological cost custo fisiológico sitophilus zeamais

ACESSO AO ARTIGO

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