By Kathy Keatley Garvey
Rice farmers seeking to protect their crops from pests without high dependency on pesticides may want to consider the sustainable pest management practice known as the “banker plant system.”
First-of-its-kind research, published in Scientific Reports by a nine-member team including UC Davis agricultural entomologist Christian Nansen, indicated that attracting alternative hosts for parasitoids of rice insect pests can help protect a rice crop. The players: a grass species, a planthopper, and an egg parasitoid.
The field and laboratory work, done in China, targeted the brown planthopper, Nilaparvata lugens, or BPH, the economically most important rice pest in Asia. Results showed that brown planthoopper densities were significantly lower in rice fields where another grass, Leersia sayanuka, was planted next to rice. The Leersia grass attracted another planthopper insect (Nilaparvata muiri) which does not infest rice.
“But N. muiri is a very good host for the important egg parasitoid, Anagrus nilaparvatae, which is also a parasitoid of the economically important pest, the brown planthopper, Nilaparvata lugens,” Nansen said. “So, by planting the grass, the parasitoids have plenty of hosts year round – even after the rice harvest season– and that ensures steady population dynamics of the parasitoid across seasons.”
“Many people are familiar with the concept of a ‘trap crop’– a sacrificial crop which is planted mixed in with or adjacent to an economically important crop and the trap crop serves to manipulate pests away by offering them a more attractive/suitable host alternative,” said Nansen. “The use of banker plants in pest management is similar to the use of trap crops, but banker plants typically have multiple ecological functions.”
Rice is the stable food of more than 50 percent of the global population, and 60 percent of the Chinese population.
Co-authors of the research paper include Zhongxian Lu, Xusong Zheng, Yanhui Lu, Junce Tian, Hongxing Xu, all of the Zhejiang Sustainable Pest and Disease Control; and Pingyang Zhu, Facheng Zhang and Guihua Chen of the Jinhua (China) Plant Protection Station. The study was jointly supported by the National Key Research and Development Program of China, Zhejiang Key Research and Development Program, and the Special Fund for Agro-scientific Research in the Public Interest.
Kathy Keatley Garvey writes about all things insect-related for the UC Davis Department of Entomology and Nematology and UC Division of Ag and Natural Resources. For more insect news, follow her Bug Squad blog.