title: Studying DDT Susceptibility at Discriminating Time Intervals Focusing on Maximum Limit of Exposure Time Survived by DDT Resistant Phlebotomus argentipes (Diptera: Psychodidae): an Investigative Report.
abstract: Extensive application of routine insecticide i.e., dichlorodiphenyltrichloroethane (DDT) to control Phlebotomus argentipes (Diptera: Psychodidae), the proven vector of visceral leishmaniasis in India, had evoked the problem of resistance/tolerance against DDT, eventually nullifying the DDT dependent strategies to control this vector. Because tolerating an hour-long exposure to DDT is not challenging enough for the resistant P. argentipes, estimating susceptibility by exposing sand flies to insecticide for just an hour becomes a trivial and futile task.Therefore, this bioassay study was carried out to investigate the maximum limit of exposure time to which DDT resistant P. argentipes can endure the effect of DDT for their survival. The mortality rate of laboratory-reared DDT resistant strain P. argentipes exposed to DDT was studied at discriminating time intervals of 60 min and it was concluded that highly resistant sand flies could withstand up to 420 min of exposure to this insecticide. Additionally, the lethal time for female P. argentipes was observed to be higher than for males suggesting that they are highly resistant to DDT's toxicity. Our results support the monitoring of tolerance limit with respect to time and hence points towards an urgent need to change the World Health Organization's protocol for susceptibility identification in resistant P. argentipes.
authors.affiliation: Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (Indian Council of Medical Research).
authors.forename: Aarti
authors.initials: A
authors.lastname: Rama
authors.affiliation: Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (Indian Council of Medical Research).
authors.forename: Shreekant
authors.initials: S
authors.lastname: Kesari
authors.affiliation: Rajendra Memorial Research Institute of Medical Sciences (Indian Council of Medical Research).
authors.forename: Pradeep
authors.initials: P
authors.lastname: Das
authors.affiliation: Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (Indian Council of Medical Research).
authors.forename: Vijay
authors.initials: V
authors.lastname: Kumar
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D003634:DDT / Q000494:pharmacology*; D004772:Entomology / Q000379:methods*; D007194:India; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D010691:Phlebotomus / Q000187:drug effects* / Q000502:physiology*; D013997:Time Factors
chemical_list: D007306:Insecticides; D003634:DDT
keywords: Dichlorodiphenyltrichloroethane(DDT); Lethal time (LT); Phlebotomus argentipus; insecticide exposure; insecticide resistance