Evaluation of rice resistance against Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) and Nephotettix cincticeps Uhler (Hemiptera: Cicadellidae) using glucometer analysis of honeydew

The brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) and the green rice leafhopper, Nephotettix cincticeps Uhler (Hemiptera: Cicadellidae) feed by sucking phloem sap from rice plants and excreting honeydew containing glucose. It is known that there are resistant rice cultivars against Ni. lugens or Ne. cincticeps, from which insects are unable to suck phloem sap. Here, we developed a simple method using a glucometer to measure glucose concentration in honeydew and use it to evaluate rice resistance against sucking insects. In case of Ni. lugens, the honeydew excreted by sucking a susceptible rice line was large in volume and glucose content. In contrast, the honeydew excreted by sucking a resistant rice line was low in volume and glucose content. In case of Ne. cincticeps, no glucose was detected in the honeydew excreted by sucking a resistant rice line, although more honeydew was excreted from the resistant rice line than the susceptible rice line. Therefore, it was suggested that Ne. cincticeps could not suck phloem sap of the resistant cultivar. Glucose analysis of honeydew using a glucometer would be useful for evaluating sucking inhibition of rice cultivars against Ni. lugens and Ne. cincticeps.