Role of enhanced detoxication in a deltamethrin-resistant population of Triatoma infestans (Hemiptera, Reduviidae) from Argentina
AUTOR(ES)
González Audino, Paola, Vassena, Claudia, Barrios, Silvia, Zerba, Eduardo, Picollo, María Inés
FONTE
Memórias do Instituto Oswaldo Cruz
DATA DE PUBLICAÇÃO
2004-05
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 µM S./i.min.) and Salta resistant colony (9.5 ± 0.8 µM 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.
Documentos Relacionados
- Toxicity of pyrethroids and repellency of diethyltoluamide in two deltamethrin-resistant colonies of Triatoma infestans Klug, 1834 (Hemiptera: Reduviidae)
- Pigmentos de olho em Triatoma infestans (Hemiptera, Reduviidae)
- Changes in nuclear phenotype frequencies following sequential cold shocks in Triatoma infestans (Hemiptera, Reduviidae)
- Susceptibility characterization of residual Brazilian populations of Triatoma infestans Klug, 1834 (Hemiptera: Reduviidae) to deltamethrin pyrethroid
- La aerotermia como alternativa para el control de Triatoma infestans (Hemiptera, Reduviidae) resistentes a deltametrina