Role of enhanced detoxication in a deltamethrin-resistant population of Triatoma infestans (Hemiptera, Reduviidae) from Argentina
Mem. Inst. Oswaldo Cruz
;
99(3): 335-339, May 2004. tab, graf
Artículo
en Inglés
| LILACS
| ID: lil-362006
RESUMO
Deltamethrin and other pyrethroids have been extensively used in Argentina since 1980, for the chemical control of Triatoma infestans Klug (Hemiptera Reduviidae). Recently, resistance to deltamethrin was detected in field populations by the survival of bugs exposed by topical application to the diagnostic dose estimated on the CIPEIN susceptible strain. Results of the current study showed low resistant ratios (RRs) to deltamethrin for the resistant populations (RR ranged from 2.0 for San Luis colony to 7.9 for Salta colony). Biochemical studies were made on the most resistant colony (Salta) and the susceptible strain (CIPEIN), in order to establish the importance of degradative mechanisms as a cause of the detected resistance. Esterase activity was measured on 3 days old first instars through phenylthioacetate and a-naphtyl acetate activities. The results showed a significant difference in no cholinesterase esterase activity from susceptible (7.6 ± 0,7 æM S./i.min.) and Salta resistant colony (9.5 ± 0.8 æM S./i.min.). Cytochrome P450 mono-oxygenase (P450) activity was measured on individual insects through ethoxycoumarine deethylase (ECOD) activity using a fluorescence micro plate reader. The dependence of ECOD activity on age and body region of the nymphs, and pH and time of incubation were studied in order to optimize the measurement. As a result, comparative studies were performed on abdomens of 2 days old first instars at pH 7.2 and 4 h incubation time. ECOD activity of first nymphs was significantly lower in the susceptible colony (61.3 ± 9.08 pg ECOD/ insect) than in the resistant one (108.1± 5.7 pg ECOD/ insect). These results suggest that degradative esterases (no-cholinesterase) and mono-oxygenases cytochrome P450, play an important role in the resistance to deltamethrin in Salta colony from Argentina.
Texto completo:
Disponible
Índice:
LILACS (Américas)
Asunto principal:
Triatoma
/
Resistencia a los Insecticidas
/
Inactivación Metabólica
/
Insecticidas
Límite:
Animales
País/Región como asunto:
America del Sur
/
Argentina
Idioma:
Inglés
Revista:
Mem. Inst. Oswaldo Cruz
Asunto de la revista:
Medicina Tropical
/
Parasitología
Año:
2004
Tipo del documento:
Artículo
País de afiliación:
Argentina
Institución/País de afiliación:
Centro de Investigaciones de Plagas e Insecticidas/AR
/
Universidad Nacional de General San Martín/AR
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