Insects 'cooperate' with viruses to expand the world

A bug that is harmful to crops is combining with viruses to accelerate their spread across the globe, Chinese scientists report.

A variant of the white butterfly Bemisia tabaci - which specializes in tobacco-derived plastic - has been called " super-spreading " insects by researchers at Zhejiang University, Hangzhou Province.

In the past 20 years, white butterflies Bemisia tabaci has spread all over the world at a dizzying speed. They are the biggest enemy of crops, with annual losses totaling several hundred million dollars. In addition, the massive movement of Bemisia tabaci butterflies always causes outbreaks of pandemics in plants caused by a virus called begomo . Begomo is a living virus parasitic on butterfly body Bemisia tabaci .

Insect experts share a common belief that Bemisia tabaci butterflies may originate from the Mediterranean or North Africa. They spread to other regions thanks to the wave of international trade. Scientists around the world take a lot of effort to find out why Bemisia tabaci butterflies spread so quickly and how they easily " knock out " other white butterflies in places where they land.

White butterfly Bemisia tabaci. (Photo: ars.usda.gov)

"I have visited many farms for many years and was surprised to see the expansion of white butterflies in China in 2002 and 2003. I have never seen this phenomenon ever. This is very bad news for farmers , " Shu-Sheng Liu, an entomologist at Zhejiang University, said.

Liu and his colleagues conducted experiments with white butterflies Bemisia tabaci . They exposed insects to healthy tobacco plants, then brought them to the tobacco fields infected with begomo virus.

The researchers found that butterflies in tobacco fields infected with the virus had a life expectancy of 6 to 7 times longer, fertility 12 to 18 times higher than those who ate healthy tobacco plants . After 8 weeks, the number of Bemisia tabaci butterflies in infected tobacco fields increased 13-fold compared to the number of congeners in healthy tobacco fields.

Meanwhile, when doing the same experiment with Chinese white butterflies, experts found that their individual numbers, longevity and fertility were no different when taken to a healthy tobacco field. viral infection.

"This is the first study to demonstrate that an insect has a beneficial relationship with the virus strain that they spread, while local insects do not have that relationship," Liu said.

Scientists judged that the virus could support Bemisia tabaci butterflies by causing plants to collapse, releasing amino acids so that butterflies can be eaten. Another explanation is that the virus neutralizes the ability of plants to secrete toxins against butterflies.

Liu added that the relationships between insects and viruses can exist in nature. Scientists should monitor them to be able to respond promptly whenever they enter a boom in quantity.

Viet Linh