Improving the safety and acceptability of autocidal gravid ovitraps

Autocidal gravid ovitraps (AGO traps) have been used for the surveillance and control of Aedes aegypti for several years. These traps use a black color and a hay infusion to attract and capture gravid females of Ae. aegypti and Culex spp (mostly Cx. quinquefasciatus) on a sticky glue board. Eggs from captured female Ae. aegypti can be washout through the screen into the infusion after heavy rains, hatch, and develop into adults. To avoid this, we tested if Bacillus thuringiensis israelensis, Spinosad, or Novaluron modified the attraction of gravid mosquitoes to the trap in field assays in Puerto Rico. We monitored 20 pairs of traps with and without each of the products for eight weeks. Results showed that neither product increased nor decreased attraction of adult Ae. aegypti or Culex spp to the traps. We also tested in field assays if trap captures of gravid mosquitoes were influenced by trap color (black, blue, green, terracotta) because having a wider choice of colors may make trap use more acceptable by residents. We monitored trap captures in four traps (each color) in each of 25 pairs of houses (two traps/house) for eight weeks, yielding 800 traps counts (200 of each color). Results showed that black traps captured similar numbers of female Ae. aegypti to blue and terracotta traps but significantly more than green traps. Captures of Culex spp were significantly larger in black traps