Indução enzimática, taxa respiratória e comportamento de populações resistentes e susceptível do caruncho do milho expostas à cipermetrina

• Autor(a) principal: Veloso, Ronnie Von dos Santos
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3862
• topic: Sitophilus zeamais; Custo adaptativo; Atividade enzimática; Sitophilus zeamais; Enzymatic activity; CNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA::ENZIMOLOGIA

Insecticides can affect the activity of enzymes of the digestive and energy metabolism of insects. Those enzymes can contribute indirectly in the detoxification process making available energy for maintenance of their defense apparatus against insecticide. The effect of the insecticide can have reflex in the metabolic rate and patterns behavior of the insects. In this study, insects of a population susceptible of the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), and two resistant populations to insecticides pyrethroid, with different demographic actings, were exposed to the cipermethrin to evaluate possible alterations in the enzymatic activity, in the metabolic rate and in the pattern behavior of this insects. Concentration-mortality bioassay were accomplished to verify the resistance level of the populations to the cipermethrin. The lethal concentration that it causes 10% of mortality of the insects susceptible (CL10), it was used in the treatment of the three populations for accomplishment of the assay. The enzymatic activity was certain for three enzymes of the energy metabolism (lypase, amylase and trehalase) and four enzymes of the digestive metabolism (cellulase, cysteine-proteinase and serine- proteinase (amydolitic and esterolytic). It was also certain the consumption of O2 and the pattern behavior of the exposed insects to the insecticide. The resistant populations had larger amylase activity, lypase and trehalase, reinforcing the hypothesis of the involvement of those enzymes with the mitigation of the costs physiologic associates to the resistance to insecticides in those populations. However, the treatment with insecticide reduced the specific activity of most of the studied enzymes. On the other hand, the consumption of O2 was similar among the populations and among exposed groups and no exposed to the cypermethrin. The insects of the resistant populations walked larger distances and they had larger medium walking speed, what can be reflex of the largest energy readiness in them. The reduction in the observed enzymatic activity can be resulted of the interference of the insecticide in the synthesis and neuropeptides liberation that affect the activity of the enzymes. Finally, the reduction of the activity of those enzymes might have affected the synthesis and liberation of a group of detoxification enzymes and the additional production of energy to mitigate the physiologic stress provoked by the insecticide.