Deleting a gene linked to the production of sex pheromones in the beet armyworm (Spodoptera exigua) causes females to lose their attractiveness to males, offering a new potential route to control the species, considered one of the world鈥檚 worst agricultural pests.
at Andong National University in South Korea and his colleagues used the CRISPR genome-editing technology to delete the gene SexiDES5 in caterpillars of the moth, which feed on a wide range of crops such as vegetables, cotton and flowers.
The deletion meant that mutant females no longer produced three pheromones associated with mating in the species. In laboratory tests, 90 per cent of males moved towards chambers containing wild-type females over mutant females when given a choice between the two.
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Further trials in a field near an onion crop found that while 160 males were attracted to traps containing wild-type females over a week, none were caught in traps containing mutants.
鈥淥ur results suggest that SexiDES5 plays a crucial role in producing sex pheromones of S. exigua,鈥� the researchers write.
They suggest that numbers of the species could be reduced using a gene-drive approach, which uses 鈥減arasitic鈥� DNA to ensure a mutation, in this case the deleted SexiDES5, spreads quicker through a population than it would by chance when mutants are introduced into the wild.
鈥淭his paper exhibits promising new paths to understanding and exploiting the ecology of insect pests by applying CRISPR techniques to manipulate pheromone production for this species,鈥� says at the University of Greenwich in London.
In practice, a gene-drive approach could involve releasing mutant males with the gene deletion. These would mate with wild females, resulting in a proportion of the offspring having the deletion. Females without the ability to attract mates would be unlikely to breed, so numbers in the next generation would be reduced.
Not all the female offspring from the modified individuals lack the sex pheromone components, but males would play a more active role in spreading the modification. Males with the deleted gene showed a normal response to pheromones from non-mutant females, demonstrating that the gene plays no role in the perception of the chemical signals, so the mutation wouldn鈥檛 stop them finding mates.
With between four and 11 generations of the moth per year, a gene drive could potentially rapidly reduce wild populations. Gene drives have been trialled before in attempts to eradicate or reduce populations of problem insects such as mosquitoes. In some cases, the goal is to make them infertile, though certain experiments have been unsuccessful.
Further tests would be required before a gene drive based on the SexiDES5 mutation could be applied in the field. 鈥淚t鈥檚 an exciting demonstration of interdisciplinary research and a prospect for the future of pest control strategies,鈥� says Fern谩ndez-Grandon.
PLoS One
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