A team of scientists from Minami Kyushu University in Miyazaki Prefecture, Japan, has accidentally stumbled upon a virus that specifically targets male insects. This unexpected discovery has the potential to aid in the control of disease-carrying insects such as mosquitoes.
The finding came about when Misato Terao, a research technician at the university, noticed a green caterpillar, identified as a tobacco cutworm, feeding on impatiens in the campus greenhouse. Instead of disposing of the intruder, Misato brought it to Yoshinori Shintani, an insect physiologist at the university, who believed it would make a good feeding source for other insects.
To their surprise, when Yoshinori checked on the caterpillar days later after placing it with other insects, he found that all 50 resulting moths were female. Intrigued by this phenomenon, Yoshinori decided to crossbreed the female moths with male moths from his own home. After multiple generations, he discovered that only three males were born out of the descendants.
This led Yoshinori and his colleague, Daisuke Kageyama from the National Agriculture and Food Research Organization in Japan, to believe that they had come across a “male killer” virus within their insect population. Further experiments and genetic analysis confirmed their suspicions, revealing telltale signs of a virus.
Despite attempts to eliminate the “male-killing” effect with antibiotics, the treatment proved ineffective as it only works against bacteria. The researchers noted that only two types of male-killing viruses have been documented, suggesting that the Spodoptera litura male-killing virus (SLMKV) they discovered may have evolved separately.
The scientists found that the SLMKV is both infectious and hereditary, as infected tobacco moths produced more females in the next generation, and subsequent generations lacked males entirely. They attributed the virus’s effect to the caterpillar’s ideal environment, which provided favorable conditions for both the tobacco cutworms and the SLMKV.
The team published their findings in The Proceedings of the National Academies of Sciences (PNAS), highlighting the potential of their discovery in controlling agricultural pests related to tobacco worms. Additionally, this breakthrough could contribute to the search for a “female killer” that could help manage disease-carrying insects like mosquitoes.
Overall, this accidental discovery by the Japanese scientists may have significant implications for population control of disease vectors and agricultural pests in the future.
