P H Yu1, H X Zhang, S Q Zhang, B Z Xu. 1. Institute of Parasitic Diseases, Hubei Academy of Medical Sciences, Wuhan 430079.
Abstract
OBJECTIVE: To determine the susceptibility of Anopheles anthropophagus and Anopheles sinensis to deltamethrin and DDT in an area where different counter-measures had been adopted. METHODS: The mortality of the vectors was examined by using the standardised WHO test. RESULTS: The mortality for tentative diagnostic dose in An. anthropophagus to deltamethrin were 83.8%, 83.7% and 84.7%, respectively in the areas where impregnated net had been used for 1 year or 3 years and DDT residual spraying had been carried out for 3 years, suggesting that An. anthropophagus was an initially resistant group. The LT50 were 8.69, 7.48 and 9.87 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to deltamethrin and DDT were 76.5%, 57.0% and 79.0%, respectively in three survey areas, suggesting that An. sinensis was a resistant group. The LT50 were 12.0, 15.4 and 11.2 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to DDT was 95.8% in impregnated net area, suggesting that An. anthropophagus was an initially resistant group. The LC50 was 0.73%. The mortality for tentative diagnostic dose in An. sinensis to DDT was 44%, suggesting that An. sinensis was a highly resistant group. The LC50 was more than 4%. CONCLUSION: A substantial use of insecticides in the rice paddy field has resulted in resistance of An. sinensis, whereas no apparent resistance of An. anthropophgus has been found.
OBJECTIVE: To determine the susceptibility of Anopheles anthropophagus and Anopheles sinensis to deltamethrin and DDT in an area where different counter-measures had been adopted. METHODS: The mortality of the vectors was examined by using the standardised WHO test. RESULTS: The mortality for tentative diagnostic dose in An. anthropophagus to deltamethrin were 83.8%, 83.7% and 84.7%, respectively in the areas where impregnated net had been used for 1 year or 3 years and DDT residual spraying had been carried out for 3 years, suggesting that An. anthropophagus was an initially resistant group. The LT50 were 8.69, 7.48 and 9.87 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to deltamethrin and DDT were 76.5%, 57.0% and 79.0%, respectively in three survey areas, suggesting that An. sinensis was a resistant group. The LT50 were 12.0, 15.4 and 11.2 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to DDT was 95.8% in impregnated net area, suggesting that An. anthropophagus was an initially resistant group. The LC50 was 0.73%. The mortality for tentative diagnostic dose in An. sinensis to DDT was 44%, suggesting that An. sinensis was a highly resistant group. The LC50 was more than 4%. CONCLUSION: A substantial use of insecticides in the rice paddy field has resulted in resistance of An. sinensis, whereas no apparent resistance of An. anthropophgus has been found.