Estudio de los mecanismos de resistencia frente a insecticidas en dos insectos plaga: Blattella germanica (L) y Frankliniella occidentalis (Pergande).
To understand the phenomenon of insecticide resistance at different levels allows the formulation of the strategies to be used for a rational management of resistance in insect pests and provides, in addition, the knowledge to increase the specificity and effectiveness of insecticides, being reduced this way its detrimental effects. With this aim this Thesis deals to undertake the study of the mechanisms involved in the resistance to insecticides, and concretely the enzymatic systems related to metabolic resistance, in Frankliniella occidentalis and Blattella germanica. Both species are examples of important pests in agriculture and public health respectively, and surprisingly they show similar underlying resistance mechanisms to the rest of the insect species. After the analysis of a field population of Blattella germanica, this one turned out to be highly resistant to the pyrethroid deltamethrin; esterases and P450 were identified among several metabolic mechanisms. Laboratory selection with deltamethrin tried to identify the mechanisms specifically related to the resistance to this insecticide and its contribution to the final phenotype. In this way, after being put under several cycles of selection, the resistance of the studied population quickly grew up from 1,58x to 102x in only three cycles, suggesting the possible selection of mechanisms of recessive nature. The incomplete supression of the resistance by synergists PBO and DEF, and cross-resistance to another pyrethroid (acrinathrin) proved that, in addition to oxidases (mainly) and esterases (to a lesser extent), other mechanisms of non-metabolic nature could be co-selected in the resistant individuals, possibly modifications of the kdr-type. The analyses of F. occidentalis samples showed a significant correlation between the elevated levels of the esterase activity and the resistance to acrinathrin, although, it did not explain the resistance in its totality, which would support the hypothesis of the multifactorial character of the resistance of the spanish field populations of Frankliniella analyzed. The mechanisms identified here, as much in Blattella as in Frankliniella, are specific of a chemical compound family, and even sometimes of composed determining; for that reason, the control strategies would have to contemplate the rotation of different classes.
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Advisor:Roca Arbós, Miguel; Garcerá Zamorano, Mª Dolores
School:Universitat de València
Source Type:Master's Thesis
Keywords:biologia funcional i antropologia física
Date of Publication:03/03/2008