Genetic Warfare: Fruit Fly Control Makes Potentially Major Advances Thanks to NCSU Research
RALEIGH – Population of Drosophila suzukii fruit flies – known as “spotted wing drosophila” which devastate soft-skinned fruits in North America, Europe and parts of South America – could be significantly suppressed with the introduction of genetically modified products. D. suzukii flies that only produce males after mating, according to new research from North Carolina State University.
D. suzukii are modified with a female lethal gene that uses a common antibiotic as a stop switch. Withholding the antibiotic tetracycline in the larval diet essentially eliminates the birth of the female D. suzukii modified male flies successfully mate with females, says Max Scott, an entomologist from the NC State who is the corresponding author of a article describing the research.
“We use a female lethal genetic system – a type of sterile insect technique – that works when a common antibiotic is not provided in the larval diets,” Scott said. “If we give the antibiotic to the larvae, the males and females survive. If we don’t, almost no female survives. Scott and coworkers have already successfully used a similar method in New World meat beetles..
The modified flies overexpressed the genes that cause cell death. The researchers used a red fluorescent protein to mark the presence of the lethal female genes.
In the study, one line of flies grown without feeding on tetracycline produced 100% males, while another line produced 98% males. During this time, the control fly lines cultured with the antibiotic produced roughly equal numbers of males and females.
“The technique worked more efficiently than expected,” Scott said.
The study also tested how the introduction of males with the lethal female gene would affect unmodified populations in laboratory cages. In one test, it took 10 generations to eliminate all female offspring. In a larger test, the researchers placed 1,000 modified males twice a week in cage populations containing around 150 to 200 pairs of wild-type flies. After eight weeks, the test cages did not produce any new eggs. Control cages were still producing more than 100 eggs per day at the end of the study.
The study shows that the genetically modified males competed well enough for the attention of fertile wild females and successfully mated with fertile females under laboratory conditions. Scott added that the study also shows that the lethal-female gene was transmitted efficiently.
Next steps could include trials confined to large cages in a greenhouse in North Carolina state, Scott said.
The study was published online in the journal Pest Management Science. Fang Li, Akihiko Yamamoto, Esther J. Belikoff, Amy Berger, and Emily H. Griffith co-authored the article. Funding for the work comes from the National Institute of Food and Agriculture, U.S. Department of Agriculture Specialty Crop Research Initiative under Agreement No. 2015- 51181-24252 and a cooperation agreement with USDA-APHIS (assignment AP17PPQS & T00C165).