The two-year study..

英語
The two-year study found that more parasitic wasps were in the hedgerows than in those fields where the borders were left to the weeds, which were studied as a control. While there were the same amount of arthropod predators—ladybugs and spiders and such—in the weedy edges, there was more diversity in and around the fields with planted edges.
日本語
境に草が残された畑より多くの寄生蜂が生垣にいたことが2年の対照群としての研究で分かった。草の生えた縁にいたテントウムシや蜘蛛など捕食性接触動物の数は同じでも、植えられた縁のある畑とその周辺には多様性があった。