Scientists in Japan have discovered a virus that selectively kills male insects and is inheritable, resulting in generations of all female insects. This finding, published in The Proceedings of the National Academies of Sciences, provides strong evidence that multiple viruses have evolved to target male insects, which could be used to control populations of pest insects and disease vectors like mosquitoes.
One of the study’s authors, Daisuke Kageyama, a researcher at the National Agriculture and Food Research Organization in Japan, believes that there are likely many similar cases waiting to be discovered in the future.
The virus was found by chance when researchers at Minami Kyushu University discovered caterpillars feeding on impatiens in the campus greenhouse. Upon further investigation, they found that all adult moths that emerged from these caterpillars were female. Breeding these females with male tobacco moths resulted in only female offspring for 13 generations, with only three males appearing.
The researchers determined that the male-killing effect was caused by a virus, which they named SlMKV. Unlike previously documented male-killing viruses, SlMKV appears to have evolved separately. Further experiments showed that the virus’s effect was diminished at higher temperatures.
Experts suggest that viral male-killers may be more common than expected and that this discovery could have implications for controlling other agricultural pests and disease-carrying species. It also contributes to the ongoing search for a “female-killer” pest controller. However, as the climate changes, researchers may lose the opportunity to study these temperature-sensitive microbes.
Anything researchers can learn about male-killers helps advance the quest for the pest controller’s holy grail: a “female-killer,” which could help fight invasive pests or disease-carrying species such as mosquitoes.
According to Anne Duplouy, an evolutionary biologist at the University of Helsinki who studies microbial symbionts in insects, time is running out for humans to learn from these temperature-sensitive microbes. As the climate changes, she said, “we are likely to be losing many of these interactions” before they can be documented.
