Oxalic Acid Inhibits Feeding Behavior of the Brown Planthopper via Binding to Gustatory Receptor Gr23a

Abstract

Plants produce diverse secondary compounds as natural protection against microbial and insect attack. Most of these compounds, including bitters and acids, are sensed by insect gustatory receptors (Grs). Although some organic acids are attractive at low or moderate levels, most acidic compounds are potentially toxic to insects and repress food consumption at high concentrations. At present, the majority of the reported sour receptors function in appetitive behaviors rather than aversive taste responses. Here, using two different heterologous expression systems, the insect Sf9 cell line and the mammalian HEK293T cell line, we started from crude extracts of rice (Oryza sativa) and successfully identified oxalic acid (OA) as a ligand of NlGr23a, a Gr in the brown planthopper Nilaparvata lugens that feeds solely on rice. The antifeedant effect of OA on the brown planthopper was dose dependent, and NlGr23a mediated the repulsive responses to OA in both rice plants and artificial diets. To our knowledge, OA is the first identified ligand of Grs starting from plant crude extracts. These findings on rice–planthopper interactions will be of broad interest for pest control in agriculture and also for better understanding of how insects select host plants.

Optimising the electrochemical reduction of CO2 to oxalic acid in propylene carbonate

“…16,17 Achieving high selectivity for individual products from CO 2 electroreduction reactions is therefore a critical goal for any potentially scalable electrochemical carbon dioxide reduction process. 18–20 A wide range of potential products have been observed from the electroreduction of CO 2 in liquid electrolytes. Of these various products, oxalic acid (C 2 H 2 O 4 ) is of interest because of its wide use in pharmaceuticals, metallurgical industries, photography, cleaning products, the food industry, bleaching agents and as an analytical reagent.…”