> The team placed [dummy targets] inside transparent plastic cages containing 50 mosquitoes and left them in the cages for 15 minutes. They [counted] the number of feeding mosquitoes at each minute.
> The team tested different scenarios, such as placing [targets] treated with either wild-type or mutant bacteria in separate cages, then putting both types of bacteria in the same cage at the same time. When given a choice, “twice as many mosquitoes were attracted to the wild type on the blood feeder rather than the mutant on a blood feeder,” Tomberlin says.
What these "mutant" type bacteria are, is explained a bit earlier:
> The team used a mutant form of S. epidermidis, in which they deleted the genetic mechanism that encodes its quorum sensing system.
And as for the "quorum sensing system", a bit earlier again:
> Bacteria "talk" to one another using a chemical system called quorum sensing.