A Multiple Cage–holding, Wind-Sensitive Vane Design for Use in Ground Adulticiding Efficacy Testing in Harris County, Texas

Abstract

A wind-sensitive vane apparatus was designed and implemented specifically to accommodate the attachment of otherwise unidirectional insecticide treatment cages used in ground ultra-low volume mosquito adulticide field tests. This cage support system is useful in keeping the potential West Nile virus and St. Louis encephalitis vector Culex quinquefasciatus caged mosquitoes oriented into the wind during field efficacy tests. Testing capacity for resistance surveillance was tripled during the 2005 season, and more reliable results were achieved as a consequence.

Field cage insecticide resistance tests againstCulex quinquefasciatusSay (Diptera: Culicidae) in Harris County, Texas, U.S.A.

“…Approximately 20–25 female mosquitoes were aspirated from designated rearing cages into cardboard treatment cages (Vessey et al ). Labeled treatment cages were placed in pre‐labeled insulated ice chests along with correspondingly labeled, 237 ml paper holding cups (Great Southwest Paper Company, Houston, TX) used for transfer of mosquitoes from treatment cages post‐application.…”

“…Separate cages, described by Vessey et al (), each containing Sebring colony adult females and the three operational area mosquito populations collected for one rearing cycle, were used. The Sebrings served as both positive and negative controls, downwind in the treatment plot and upwind of applications.…”

“…The field test plot was a 3 × 3 design with a row of three cage stakes positioned at 30.4, 60.9, and 91.4 m distances downwind from aerosol application, and cage stakes positioned 30.4 m apart from one another throughout the plot as described in other similar studies (Groves et al, Crockett et al ), with three negative control stakes placed upwind of the test plot. The cage support system at each of nine positions downwind and the three negative control positions upwind stood 1.5 m tall, and allowed four cages of mosquitoes (three cages containing separate laboratory mosquito populations, and one cage containing Sebring as positive controls) to automatically orient into the wind (Vessey et al ). The test location was a large open field located in southeast Harris County, with a reasonably consistent wind direction for the test plot relative to spray path, no wind obstructions, little human activity, and paved road surface on three sides on which the application vehicle could travel if wind direction had necessitated (Figure ).…”

“…Upon transfer of mosquitoes into the cup, a 12.7 cm 2 section of the burgundy tulle was placed across the cup and secured with the ring of the original lid. Labeled cages were removed from ice chests prior to a test, affixed to the cage arms, carried into the plot by personnel assigned a particular distance stake position, and placed on the support stakes as described by Vessey et al (2007). After five min postapplication, assigned personnel retrieved cage arms and returned them to the upwind transfer station corresponding to that distance.…”

Evaluation of field resistance in field‐collected mosquito Culex quinquefasciatus Say through quantification of ULV permethrin/PBO formulation in field bioassays

“…quinquefasciatus mosquitoes, HCPH performs field cage tests (FCTs). 8,9,18 These tests utilize a pesticide-susceptible Sebring strain (SEB) of caged mosquitoes as controls to verify the reach of adulticides while simultaneously estimating the control efficacy by assessing the mortality of field-collected mosquitoes. The use of the susceptible strain as sole reference to verify good pesticide coverage or reach is, however, insufficient to interpret the results of the FCT.…”