Lopes, K.V.G. and Silva, L.B. and Reis, A.P. and et al, . (2010) Modified α-amylase activity among insecticide-resistant and -susceptible strains of the maize weevil, Sitophilus zeamais. Journal of Insect Physiology, 56 (9). pp. 1050-1057.
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Abstract
Fitness cost is usually associated with insecticide resistance and may be mitigated by increased energy accumulation and mobilization. Preliminary evidence in the maize weevil (Coleoptera: Curculionidae) suggested possible involvement of amylases in such phenomenon. Therefore, α-amylases were purified from an insecticide-susceptible and two insecticide-resistant strains (one with fitness cost [resistant cost strain], and the other without it [resistant no-cost strain]). The main α-amylase of each strain was purified by glycogen precipitation and ion-exchange chromatography (≥70-fold purification, ≤19% yield). Single α-amylase bands with the same molecular mass (53.7 kDa) were revealed for each insect strain. Higher activity was obtained at 35–40 °C and at pH 5.0–7.0 for all of the strains. The α-amylase from the resistant no-cost strain exhibited higher activity towards starch and lower inhibition by acarbose and wheat amylase inhibitors. Opposite results were observed for the α-amylase from the resistant cost strain. Although the α-amylase from the resistant cost strain exhibited higher affinity to starch (i.e., lower Km), its Vmax-value was the lowest among the strains, particularly the resistant no-cost strain. Such results provide support for the hypothesis that enhanced α-amylase activity may be playing a major role in mitigating fitness costs associated with insecticide resistance.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Fitness cost; Cost mitigation; Insecticide resistance; Hydrolases; Stored grains insects; Enzyme kinetics |
| Author Affiliation: | a Departamento de Bioquímica e Biologia Molecular, Instituto de Biotecnologia Aplicada à Agropecuária (BIOAGRO), Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil b Departamento de Biologia Animal, Universidade Federal de Viçosa, Viçosa, MG 36571-000, Brazil c Instituto Nacional de Ciência e Tecnologia em Interações Planta-Praga (INCT-IPP), Universidade Federal de Viçosa, Viçosa, MG 36570-000, Brazil |
| Subjects: | Plant Protection |
| Divisions: | Maize |
| Depositing User: | Mr B Krishnamurthy |
| Date Deposited: | 23 Mar 2012 06:23 |
| Last Modified: | 23 Mar 2012 06:24 |
| Official URL: | http://dx.doi.org/10.1016/j.jinsphys.2010.02.020 |
| URI: | http://eprints.icrisat.ac.in/id/eprint/4048 |
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