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

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