Insects do a lot more harm than ruining picnics. Some insects spread devastating diseases, while others cause staggering economic losses in agriculture. To control some of these pests, scientists are developing males that make sex a deadly event.
The stakes are high. Mosquitoes carry viruses such as dengue, West Nile and Zika, as well as parasites that cause malaria. Researchers estimate that mosquitoes have caused the deaths of 52 billion people overall – nearly half of all the humans that have ever lived.
Other insects cause major crop damage, jeopardizing the food supply and driving up prices. According to the Food and Agriculture Organization of the United Nations, 20% to 40% of global crop production is lost to pests annually at a cost of US$70 billion.
Pesticides have been the front-line defense against insects, but many bugs have evolved resistance to these chemicals. Some pesticides can indiscriminately kill beneficial insects, harm the environment and endanger human and animal health. Some researchers worry that certain pesticides can cause cancer or have damaging effects on human nervous and endocrine systems.
I’m a microbiology researcher studying infectious disease. New solutions that do not harm humans and the environment to control disease-carrying insects and agricultural pests could lead to fewer people contracting dangerous diseases. In the past few years, a variety of genetic engineering approaches have emerged as promising tactics to combat problematic insects.
Genetically modified insects
To avoid the problems associated with pesticides, scientists have devised new approaches that genetically alter the insects themselves in ways that cause their population to crash or render them incapable of transmitting disease – a strategy called genetic biocontrol.
Genetic biocontrol entails genetically modifying insects to curb their populations.
The idea to suppress an insect population by flooding it with sterile males has been around for decades. Since the 1950s, scientists have been using radiation to create infertile male mosquitoes. These sterile males mate with females but produce no offspring. Since females are engaged in a lot of unproductive mating, the overall population tends to decline.
In the past two decades, genetic engineering has been used to introduce dominant lethal genes into insect populations. In this approach, the offspring of genetically modified males inherit a gene that kills them before they reach reproductive age. A field trial in Brazil found that this strategy reduced the target mosquito population up to 95%. Another approach on the horizon involves releasing insects genetically modified to be poor carriers of pathogens that cause disease.
Despite these advances, a key shortcoming to current genetic biocontrol methods is that they take time. At least one generation needs to be born before the population suppression…
