Spiroplasma-like organisms closely associated with the gut in five leafhopper species (Hemiptera: Cicadellidae)

Abstract

Spiroplasmas are bacteria in the Class Mollicutes that are frequently associated with insects and/or plants. Here, we describe the ultrastructure, localization, and occurrence of apparent commensal/symbiotic spiroplasma-like organisms (SLOs) in the midgut and hindgut of five leafhopper species from laboratory-reared colonies. Those found in Dalbulus elimatus, Endria inimica, and Macrosteles quadrilineatus were long and tubular shaped, whereas those in Dalbulus maidis and Graminella nigrifrons were shorter and mostly rod-shaped in their host organisms. These SLOs were found in great numbers in the gut lumen frequently associated with the gut microvilli, but unlike the plant-pathogenic mollicutes, they did not seem to invade the gut epithelium or other tissues in any of these five leafhopper species. Large accumulations of these gut-associated organisms were more commonly found by confocal laser scanning microscopy in males than in females and in crowded than in singly reared leafhoppers. Ultrastructural evidence suggests that these SLOs may be horizontally transmitted between leafhoppers by contamination of the mouth parts with leafhopper excretions.