Phlebotomus argentipes is the vector of visceral leishmaniasis in India. Which of the following bionomic characteristics makes indoor residual spraying (IRS) with DDT highly effective against this vector?
- A It is a daytime biter that rests outdoors after feeding
- B It is an endophilic (indoor-resting), endophagic (indoor-feeding) sand fly with a short flight range ✓
- C It breeds in stagnant water collections around dwellings
- D It transmits leishmaniasis only transovarially without a vertebrate reservoir
Explanation
Phlebotomus argentipes is strictly endophilic (rests indoors on walls after feeding) and endophagic (bites primarily indoors at night). Its short flight range (rarely >50 m from breeding site) keeps it predominantly within and around human dwellings. These behaviours make IRS with DDT (or synthetic pyrethroids) highly effective — the sand fly encounters lethal insecticide residues when resting on sprayed surfaces after feeding. Exophilic/exophagic vectors (option A) rest outdoors and would avoid contact with IRS. Sand flies breed in moist, dark, humid organic debris (not stagnant water — option C). Leishmania has vertebrate reservoirs and is not transovarially transmitted.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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