Honey-baited FTA cards for arbovirus surveillance: Sensitivity, mosquito feeding rates and feeding time course

Mosquito-borne diseases are a major cause of morbidity and mortality worldwide. A significant obstacle to reducing the burden of these diseases is identifying where and when mosquito infection rates are highest. Honey-baited FTA cards have recently emerged as a sensitive and flexible technique for detecting arboviruses that are circulating in a given population of mosquitoes. Debate remains however, about the sensitivity of this method and how long mosquitoes should be allowed to feed on the cards to maximize the effectiveness of this technique. Here we report on the results of the first large-scale addition of honey-baited FTA cards to an existing CO2-baited EVS miniature light trap mosquito surveillance program. Blue dye was added to the honey bait to detect whether mosquitoes had fed from the FTA card. We report on the virus detections in this study, and the minimum percent of mosquitoes that fed (had blue dye inside them) and the feeding time course. Feeding rates were found to be significantly different among trap locations and mosquito species. In field trials, blue dye could be detected in 19% of trapped mosquitoes, while in a captive study, 65% and 72% of mosquitoes were detectably blue at 24 and 48 hours, respectively. We discuss the implications of these findings for FTA card use in arbovirus surveillance and suggest ways to improve feeding rates in field trials.