Insects that spread disease and damage crops could be controlled by inserting poisons from spider and sea anemone venom into males’ reproductive systems, killing females they mate with.
Samuel Beach and at Macquarie University in Sydney, Australia, have developed what they call the “toxic male technique”, where insects are genetically engineered to express the venom proteins of other species in the glands of their reproductive system.
They tested seven different venom proteins in males of the fruit fly Drosophila melanogaster. Those from the spider Phoneutria nigriventer and the sea anemone Anemonia sulcata performed the best, reducing the median lifespans of mated females by 37 to 64 per cent.
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The researchers then modelled the possible impact of using the approach against the yellow fever mosquito (Aedes aegypti) based on data from field trials of other genetic pest-control technologies.
They found that even modest rates of mortality could reduce female populations faster than other approaches and decrease blood feeding by 40 to 60 per cent, making the method particularly suited for rapid responses to viral diseases spread by insect bites.
In mating tests, the engineered males were able to court females just as well as wild type males – a potentially crucial factor for success in the field.
Many problematic insects, such as the screwworm parasite, have been successfully controlled by releasing large numbers of sterile males into the wild, so that many females mate unsuccessfully and the population of the next generation is reduced. Another approach already used against malaria-carrying mosquitoes involves genetically modified males with a dominant lethal gene that kills offspring at the larval stage.
The toxic male technique addresses a drawback of these approaches, which is the fact that females that have mated can still cause harm by spreading diseases and feeding on valuable food crops.
Maselko says pests are unlikely to develop resistance to the venom proteins as they target very specific genetic pathways, but the best approach would be to use strains that transmit multiple insecticidal proteins.
“We need another two to three years to develop strains of mosquitoes ready for field trials and to perform experiments needed to ensure the technology doesn’t have unexpected negative effects,” says Maselko. “After that, commercial deployment could be possible in another couple of years.”
The key to success is ensuring the protein is expressed in a way that doesn’t harm the carrying male, says at the University of York, UK, who was not involved in the work.
“There’s no built-in sex specificity in the toxin, so you have to express it in just the right place and nowhere else,” says Alphey.
“We know so much more about Drosophila genetics than we do about any pest insect. Getting the exact expression in exactly the right place would be more problematic in a pest, but I don’t see any fundamental reason why you couldn’t get this to work,” he says.
Nature Communications
