Pouncing spider, flying mosquito: blood acquisition increases predation risk in mosquitoes

Female mosquitoes dramatically increase their mass when blood feeding on their hosts. Such an increase could impact mosquito mortality risk by reducing escape speed and/or agility. We used two laboratory-based experiments to test this notion. In the first, we allowed mature female Anopheles gambiae mosquitoes to feed from 0 to 4 min and then attacked those females with an artificial predator. We videotaped subsequent escape response of each mosquito. Analysis of those responses clearly demonstrated an inverse relationship between increased mass and escape speed. In the second experiment, we exposed both blood-engorged and unfed A.gambiae females to single zebra spiders (Salticus scenicus) in small plexiglass cages. Here, we focused on mosquito escapes from searching and pouncing spiders. We found that engorged mosquitoes were three times less likely to escape searching spiders compared to unfed conspecifics. Thus we conclude that blood feeding has substantial state-dependent risk both at the host (experiment 1) and after feeding (experiment 2). Such risk can be extended to a broad range of taxa.