Alteration in the Stylet Probing Behavior and Host Preference of the Vector Matsumuratettix hiroglyphicus (Hemiptera: Cicadellidae) After Infection with Sugarcane White Leaf Phytoplasma.

Abstract

The leafhopper (Matsumuratettix hiroglyphicus (Matsumura) (Hemiptera: Cicadellidae)) is a crucial insect vector of the phytoplasma associated with sugarcane white leaf (SCWL) disease. The aim of this study was to compare the stylet probing behaviors of M. hiroglyphicus on healthy sugarcane plants, asymptomatic, and symptomatic SCWL-infected sugarcane plants, using DC electropenetrography. We also used host-selection preference (free-choice) assays to identify the preferred types of host plants, and scanning electron microscopy to observe stylet puncture holes and salivary flanges after leafhopper probing. According to a quantitative analysis of M. hiroglyphicus stylet probing, mean durations per insect of both phloem ingestion (waveform D; the phytoplasma-acquisition behavior) and phloem salivation (waveform C; the phytoplasma-inoculation behavior) were significantly longer on both types of infected sugarcane than on healthy plants. These longer overall durations were mainly because the same number of significantly longer-duration C and D events was performed on infected sugarcane compared with healthy plants. On free-choice tested plants, M. hiroglyphicus displayed a significantly greater preference to settle on the infected plants (both types) than the healthy sugarcane. These results provide the first empirical evidence that acquiring the SCWL phytoplasma alters the host selection and stylet probing behaviors of its main vector (M. hiroglyphicus). Our study thus contributes to a better understanding of the interactions between the insect vector and SCWL phytoplasma-infected plants, and will aid in developing novel disease management tactics for sugarcane.