Comparison of two sampling methods for domestic populations of Triatoma infestans in north-west Argentina.
In mud-and-thatch houses of Santiago del Estero Province, north-west Argentina, where no insecticides had been sprayed officially to control domestic infestations of the Chagas disease vector Triatoma infestans (Klug) (Hemiptera: Reduviidae), two knockdown (KD) insecticidal collection procedures were compared with the standard flush-out (FO) method for sampling T. infestans. Bugs were collected by FO using 0.2% tetramethrin in bedrooms of (1) 41 houses of Amamá village employing 1 man-hour of capture effort per house, and (2) 19 houses of Trinidad and Mercedes villages employing 4 man-hours/house. From the same houses, 2-5 days after the manual FO collection, bugs were collected by KD indoor-spraying of deltamethrin 25 mg a.i./m2 in Amamá, or burning of one gamma-HCH (= gamma-BHC) fumigant tablet 3.1 g of gamma-isomer) per bedroom in Trinidad and Mercedes. The majority of infestations were detected by both methods, the proportion of positive houses being 81% at Amamá and 95% at the other villages. Although the FO method was more sensitive, at least because it was applied first, the KD method detected infestations in 25% of houses where bugs were not found by FO. Bug densities estimated by FO or by subsequent KD in each house were significantly correlated: r = 0.795 for deltamethrin; r = 0.882 for gamma-HCH. Compared with FO collections of T. infestans large stages, i.e. adults plus fourth and fifth instar nymphs, the KD catch averaged 0.88 x with deltamethrin and 0.57 x with gamma-HCH, regardless of the apparent population density of bugs per house. However, the KD method has practical advantages of speed and standardization.
Gürtler
R E
RE
Laboratorio de Ecología General, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
Schweigmann
N J
NJ
Cecere
M C
MC
Chuit
R
R
Wisnivesky-Colli
C
C
D000818:Animals; D001118:Argentina; D004772:Entomology / Q000379:methods*; D001556:Hexachlorocyclohexane; D006798:Housing; D007306:Insecticides; D009570:Nitriles; D011156:Population Density; D011722:Pyrethrins; D014224:Triatoma
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin; D001556:Hexachlorocyclohexane; C009424:tetramethrin