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Identifier 000451942
Title Functional analysis of insecticide resistance mechanisms on medically important and from agriculturally important insects
Alternative Title Λειτουργική ανάλυση μηχανισμών ανθεκτικότητας σε εντομοκτόνα σε έντομα υγιειονομικής και από έντομα αγροτικής σημασίας
Author Κόκκας, Εμμανουήλ Σ.
Thesis advisor Βόντας, Ιωάννης
Reviewer Δελιδάκης, Χρήστος
Kiamos, Inga-Siden
Abstract The use of chemical insecticides for the control of destructive insects is one of the most efficient and cost-effective methods employed for their control. However, their constant use in vector control and agriculture over the years has led to the establishment of resistant insect populations, therefore creating an ever growing need to understand the molecular mechanisms that govern insecticide resistance. One of the most widely used insecticide classes in the control of vectors of diseases are pyrethroids, which bind on the voltage gated sodium channel altering its kinetics, whereas neonicotinoids, selective agonists of the acetylcholine receptor, are traditionally used in agriculture, although they have recently started being used in vector control as well. Resistance against pyrethroids is very prevalent in the major malaria vector mosquito Anopheles gambiae. Specific neonicotinoid resistance mechanisms haven’t been identified in mosquitoes yet, although they are common in agricultural pests. In the current bibliography, most studies approach insecticide resistance by examining individual mechanisms whereas here, various resistance mechanisms from medically and agriculturally important insects and their combinations are analyzed. Firstly, pyrethroid insecticide resistance mechanisms utilized by An. gambiae are functionally analyzed using laboratory An. gambiae strains. Specifically, the resistance effect of the L1014F kdr target-site mutation, that is heavily associated with pyrethroid insecticide resistance, in combination with the overexpression of known pyrethroid metabolizing P450 enzyme Cyp6M2 is studied. Mosquitoes harboring the L1014F mutation and overexpressing Cyp6M2 show a synergistic effect between the mechanisms, displaying significantly higher pyrethroid resistance than the sum of the isolated mechanisms. Another object of this study is the determination of the resistance effect conferred by the combination of neonicotinoid resistance mechanisms from the agriculturally important insects Myzus persicae, Aphis gossypi and Bemisia tabaci when introduced in the model organism Drosophila melanogaster. More specifically, the R81T targetsite mutation, which is known to confer neonicotinoid resistance, is studied in transgenic flies also overexpressing known well-characterized neonicotinoid metabolizing enzymes Cyp6M1 and Cyp6CY3. R81T and Cyp6CM1 appear to work in great synergism, while R81T and Cyp6CM1 display a higher resistance phenotype than the addition of the effects of each individual mechanism, but the effect- even though synergistic is moderate. Finally, the creation of transgenic Anopheles gambiae strains is attempted, utilizing a CrispR/Cas9 transgenesis approach. The reversion of the L1014F mutation to its wild type state is attempted in a multi-insecticide resistant mosquito strain in order to measure its contribution to the pyrethroid resistance phenotype. The introduction of the R81T mutation in an insecticide susceptible An. gambiae strain is also attempted in order to measure its potential resistance effect and validate the possibility of this mutation being viable and developing in mosquitoes, due to increasing neonicotinoid use in vector control. No transgenic strains are reported as of yet, although experimental planning, creation of the necessary constructs and some early embryo microinjection attempts in order to generate these strains have been performed.
Language English
Subject Mosquiotoes
Neonicotinoid insecticides
Pyrethroid insecticides
Synergism
Κουνούπια
Νεονικοτινοειδή εντομοκτόνα
Πυρεθροειδή εντομοκτόνα
Συνεργισμός
Issue date 2022-11-25
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/9/8/5/metadata-dlib-1667384905-795682-27142.tkl Bookmark and Share
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