Mosquitoes' Choice of Flower or Flesh.

• Position: EVOLUTIONARY GENETICS - Wyeomyia smithii

Imagine a world in which mosquitoes choose blossoms over blood--nice, right? There already exists such a species (Wyeomyia smithii), in which most of the bugs refuse blood meals in favor of sweet floral nectar, and research is helping to explain the evolutionary genetics of the switch from blood sucker to flower fanatic.

The species, which lives in bogs and is present throughout much of North America, mostly dines strictly on plants but, in Florida, there is a split in the population, as some of the mosquitoes go for blood.

Researchers, including entomologist David Denlinger, believe that all of the mosquitoes in the species once relied on blood for nourishment and that, over time, some evolved to prefer plants. In a study published in Proceedings of the National Academy of Sciences, Denlinger and his colleagues examined the genes of the blood eaters and the vegetarians and found differences that made good sense. The mosquitoes that still eat blood had more genes involved in sniffing out odors and fewer genes involved in light sensitivity.

"It would make sense that finding blood meals would depend on odor detection and that nectar eaters would rely more on vision to find food," explains Denlinger.

Researchers also found a number of genes associated with digestion of proteins in the blood-eating mosquitoes. They examined genetics right as the mosquitoes were about...