Critical evaluation of quantitative sampling methods for Aedes aegypti (Diptera: Culicidae) immatures in water storage containers in Vietnam

Journal Publication ResearchOnline@JCU
Knox, Tessa B.;Yen, Nguyen Thi;Nam, Vu Sinh;Gatton, Michelle L.;Kay, Brian H.;Ryan, Peter A.
Abstract

In response to an identified paucity of information on the size and composition of immature Aedes aegypti (L.) (Diptera: Culicidae) populations in large field containers, we assessed net sampling and pumping/sieving methods for estimating and enumerating third (III)/fourth (IV) instar and pupal populations. Sweep net detection thresholds (number above which ≥90% chance of a positive sample) were ≤28 immatures for seven different container types (115-3000 liter jars and tanks) in the laboratory, and mean recovery percentages varied by container type (6.15-41.29 and 7.39Ð33.10% for III/IV instars and pupae, respectively).A pumping method or hand bailing was applied in the field for the collection of III/IV instars and pupae from 406 receptacles, of which 343 had been previously sampled via a five-sweep netting technique. Larvae were 9.30 times more prevalent than pupae, and abundance varied by container type with means of 36-537 III/IV instars and 6-53 pupae per receptacle. Sweep netting for III/IV instars effectively identiÞed 86.2% of Ae. aegypti-positive containers, whereas sampling for pupae detected only 43.1% of positive containers. When conversion factors (inverse of laboratory recovery percentages) were applied to field net sampling data, estimates of container populations were more accurate for III/IV instars than pupae (maximum R2 = 0.610 and 0.328, respectively); however, the relationship between immature abundance and emergent adult populations remains to be defined

Journal

Journal of Medical Entomology

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Volume

44

ISBN/ISSN

1938-2928

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Issue

2

Pages Count

13

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Publisher

Entomological Society of America

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DOI

10.1093/jmedent/44.2.192