Studies on the duration of effectiveness of DDT spray for the control of vector sandfly, Phlebotomas argentipes annandale & brunethi (Diptera: Psychodidae) in a Kala-azar endemic area in Bihar, India

摘要

Leishmantasis or Kala-azar is transmitted by bite of sandfly, Phelebotomas argentipes in India. Field observations showed that spraying of DDT @ 1 gm/mm in three village of Vaishali district and one village in Patna district gave 2.5 to 3.5 months protection against vector Ph. argentipes in Bihar. The density of sandfly Ph. argentipes was reduced to zero but reappeared after 2.5 months in village Chakar sole and 3.5 months in Dakshini Tola, while in village Ravidas Tola Ph. argentipes developed somedergee of tolerence to spray of DDT. The result obtained from village Hulashchak of Patna district (no insecticidal pressure for last 25 years)showed that after DDT spray Ph. argentipes disappeared but reappeared within 7 months period showing high susceptibly to residual spray of DDT. There was no significant difference in spraying carried at height (6 feet of height) and entire structure of indoor dwellings.