Impact of visual features on capture of Aedes aegypti with host decoy traps (HDT)

The host decoy trap (HDT) is a surveillance trap that presents a combination of heat, visual and odour stimuli to attract bloodmeal-seeking mosquitoes. Here we employed a semi-field study to demonstrate the role of the visual attributes present on the HDT on the effectiveness of Aedes aegypti capture. Our results show that the HDT is an effective means of capturing Ae. aegypti mosquitoes in semi-field conditions, with a per trial capture rate of up to 69% across four visually distinct HDTs. The solid black coloured HDT captured more mosquitoes than HDTs with black-white stripes, black-white checkerboard patches or solid white colour by a factor of 1.9, 1.7 and 1.5, respectively. In all cases, mosquito capture was not evenly distributed on the HDT surface, with captures on the HDT's outer downwind half, away from the odour delivery, exceeding captures on the inner upwind half. We conclude that the solid black surface of the original HDT design is more effective than the other surfaces (white or black/white patterns) for the capture of Ae. aegypti. Our results demonstrate that mosquito attraction to the thermal and odorant cues of the HDT is modulated by visual information.