Histological and quantitative image analyses of rice gall formed by orange leafhopper Cicadulina bipunctata (Hemiptera: Cicadellidae)

The orange leafhopper, Cicadulina bipunctata (Melichar) (Hemiptera: Cicadellidae), is an insect pest of various Poaceae plants. Feeding by this leafhopper species induces growth suppression and gall formation, which is characterized by severe swelling of leaf veins, named wallaby ear symptoms. In this study, we performed histological analysis of the cell differentiation in the galled leaves of rice seedlings and devised a new method to quantify the degree of gall formation. In the histological study, abnormal vascular cell patterning and differentiation were observed in the galled leaves. Morphological changes during gall formation were quantitatively evaluated through image analysis.