White-Eyed Fruit Flies: How Improvements in Gene Editing Could Aid in Pest Managemen

The SIT involves scientists raising the target fruit fly species in the lab, sterilizing the flies by exposing them to a certain amount of radiation while they are still pupae, and releasing large amounts of the newly sterile flies into nature. When the released, sterile flies mate with wild flies, they produce infertile eggs that never hatch and, over time, this reduces—and hopefully eliminates—the population of flies. “But research shows that if you only release sterile males—instead of sterile males and females at the same time—you can more efficiently accomplish management,” says Daniel Paulo, PhD, a researcher in the Department of Plant and Environmental Protection Sciences at the University of Hawaiʻi at Mānoa. Male flies mate more often than females and don’t damage fruits in the field because they don’t lay eggs. Male-focused SIT programs also guarantee sterile males are using their energy to mate with wild-type females, not with females who were also sterilized. So, scientists target male flies with sterilization efforts by using a classic genetic method called genetic sexing, which helps create sex-specific, visible physical characteristics or markers (called phenotypes) among fruit flies. These phenotypes make it possible for scientists to tell the two sexes apart more easily and parse the males and females before sterilizing. A colony of such flies is called genetic sexing strain (GSS). A GSS requires a phenotype scientists can create by inducing a genetic change, called a mutation, that leads to a visible characteristic. Next, they link the normal, non-mutated visual marker to the male sex.

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