Visual threats reduce blood-feeding and trigger escape responses in Aedes aegypti mosquitoes.

The diurnal mosquitoes Aedes aegypti are vectors of several arboviruses, including dengue, yellow fever, and Zika viruses. To find a host to feed on, they rely on the sophisticated integration of olfactory, visual, thermal, and gustatory cues emitted by the hosts. If detected by their target, this latter may display defensive behaviors that mosquitoes need to be able to detect and escape in order to survive. In humans, a typical response is a swat of the hand, which generates both mechanical and visual perturbations aimed at a mosquito. Here, we used programmable visual displays to generate expanding objects sharing characteristics with the visual component of an approaching hand and quantified the behavioral response of female mosquitoes. Results show that Ae. aegypti is capable of using visual information to decide whether to feed on an artificial host mimic. Stimulations delivered in a LED flight arena further reveal that landed Ae. aegypti females display a stereotypical escape strategy by taking off at an angle that is a function of the direction of stimulus introduction. Altogether, this study demonstrates that mosquitoes landed on a host mimic can use isolated visual cues to detect and avoid a potential threat.

Development of an Attractive Toxic Sugar Bait for the Control of Aedes j. japonicus (Diptera: Culicidae).

Both female and male mosquitoes consume sugar meals to obtain carbohydrates used for energy. This behavior has recently been identified as a possible mosquito control target, as the World Health Organization has urged for the development of integrated vector management. This is critical as many medically important mosquito species are developing insecticide resistance, resulting in current control strategies becoming less effective. Additionally, the traditional use of insecticides is detrimental to many beneficial insects such as pollinators. The main goal of this study was to develop an attractive toxic sugar bait (ATSB) to limit the populations of a local invasive mosquito, Aedes j. japonicus (Theobald) (Diptera: Culicidae). An ATSB is a lure bait composed of an attractant odorant, a toxic component, and sugar that the mosquitoes can feed on. ATSBs are cost-effective, sustainable, environmentally friendly, and can be species-specific. Mosquitoes were isolated into cages or cups and each group had access to either a toxic sugar solution (containing boric acid), a control solution or a choice between the two. We tested multiple fruits, including mango, peach, blueberries, and blackberries, as well as a soda and grape juice and monitored their survival for 96 h. We found that this species fed on all tested fruit solutions and that the groups that imbibed toxic solutions died within 48 h, indicating that boric acid is an effective oral toxin against Ae. j. japonicus. Further experiments will be conducted in the field to determine the ATSBs efficacy and to monitor potential effects on off-target species.