title: Critical evaluation of quantitative sampling methods for Aedes aegypti (Diptera: Culicidae) immatures in water storage containers in Vietnam.
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 > or = 90% chance of a positive sample) were < or = 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 7.39-33.10% 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 identified 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.
authors.affiliation: Queensland Institute of Medical Research, Post Office Royal Brisbane Hospital, Brisbane, Australia. tessa.knox@qimr.edu.au
authors.forename: Tessa B
authors.initials: TB
authors.lastname: Knox
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Yen
authors.forename: Vu Sinh
authors.initials: VS
authors.lastname: Nam
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Gatton
authors.forename: Brian H
authors.initials: BH
authors.lastname: Kay
authors.forename: Peter A
authors.initials: PA
authors.lastname: Ryan
mesh_terms: D000330:Aedes / Q000502:physiology*; D000818:Animals; D003715:Dengue / Q000517:prevention & control*; D004784:Environmental Monitoring / Q000379:methods*; D007303:Insect Vectors / Q000502:physiology*; D007814:Larva; D009032:Mosquito Control / Q000379:methods; D011156:Population Density; D011679:Pupa; D013997:Time Factors; D014744:Vietnam; D014867:Water
chemical_list: D014867:Water