Proportional transfer of chemical elements from rice plants to rice brown planthopper (Nilaparvata lugens [Stål], Hemiptera: Delphacidae) and its honeydew

Abstract

The chemical elements Fe, Mg, Cu, Zn, and Mn are involved in the various physiological processes of plants. A change in the contents of some chemical elements in rice (Oryza sativa L.) plants is associated with resistance to pests; this includes the slow growth of rice brown planthopper (Nilaparvata lugens Stål) populations. By manipulating the concentrations of Zn, Mn, Fe, and Cu in a hydroponic solution, we tracked the flow of these elements from a hydroponic solution through the rice plant phloem sap, to planthoppers, and ultimately the honeydew excreted by N. lugens. The results showed not only that the contents of Zn, Mn, Fe, and Cu in the rice plants increased with their concentrations in the hydroponic solution but also that the increase in the levels of these four elements in the hydroponic solution affected the level (positively or negatively) of other chemical elements in the rice plants. Furthermore, some of the changes in element levels in the rice plants were reflected in the content of the phloem sap, N. lugens itself and its honeydew. Among the four chemical elements manipulated in the hydroponic solution, only elevated levels of Mn and Na were proportionally transferred to both the rice plants and N. lugens. Therefore, those particular elements could be used as markers to match N. lugens individuals to the rice plants on which they have fed. Our findings have potential applications for determining the provenance of N. lugens migratory populations by examining the levels of chemical elements in N. lugens immigrants, which would lead to a better understanding of the migration sources and routes of this insect.

Keywords:

• rice brown planthopper
• phloem sap
• Oryza sativa
• chemical element
• conductance

Acknowledgments

This research was supported by the Major State Basic Research and Development Program of China (973 program, grant No. 2010CB126200) and the National Natural Science Foundation of China (grant No. 30870393). We thank Professor S.L. Gu of Yangzhou University for his help with the statistical analysis and Dr. J.G. Du at the State University of New York for revising an early version of the manuscript.