OSAKA >> A new method of collecting insect DNA involves simply spraying water on plants, a group of researchers has announced. The water, used to collect trace amounts of DNA contained in feces and saliva that remain on leaves and stems, can help identify insects and other arthropod species on plants.

A report on the method has been published in the international science journal Scientific Reports.

Traditionally, surveying species on plants has entailed labor-and time-intensive methods such as visual observation and capturing the arthropods in traps. And many small arthropods are difficult to find and observe.

The researchers focused on environmental DNA, which refers to DNA in excrement and body fluids released into rivers, ocean or soil. Analyzing river water, for example, could lead to identifying the fish living there.

Researchers sprayed water on 37 samples of eggplants and cabbage plants and collected the water that flowed over the surface of leaves and stems. They also observed seven species, including larvae of moths and aphids. But in analyzing the water, the DNA for 22 other species were identified. The researchers said analysis of rainwater that flowed over the surface of the plants also produced similar data.

“It is an interesting idea to collect DNA by spraying water,” said Michio Kondo, a professor and community ecology expert at Tohoku University. “Since data can be obtained easily, the method could be useful for such matters as pest infestation forecasts.”